diff --git a/Lib/pickle.py b/Lib/pickle.py
index 25ffd03..8a8e623 100644
--- a/Lib/pickle.py
+++ b/Lib/pickle.py
@@ -174,7 +174,7 @@
 
 # Pickling machinery
 
-class Pickler:
+class _Pickler:
 
     def __init__(self, file, protocol=None):
         """This takes a binary file for writing a pickle data stream.
@@ -182,21 +182,19 @@
         All protocols now read and write bytes.
 
         The optional protocol argument tells the pickler to use the
-        given protocol; supported protocols are 0, 1, 2.  The default
-        protocol is 2; it's been supported for many years now.
-
-        Protocol 1 is more efficient than protocol 0; protocol 2 is
-        more efficient than protocol 1.
+        given protocol; supported protocols are 0, 1, 2, 3.  The default
+        protocol is 3; a backward-incompatible protocol designed for
+        Python 3.0.
 
         Specifying a negative protocol version selects the highest
         protocol version supported.  The higher the protocol used, the
         more recent the version of Python needed to read the pickle
         produced.
 
-        The file parameter must have a write() method that accepts a single
-        string argument.  It can thus be an open file object, a StringIO
-        object, or any other custom object that meets this interface.
-
+        The file argument must have a write() method that accepts a single
+        bytes argument. It can thus be a file object opened for binary
+        writing, a io.BytesIO instance, or any other custom object that
+        meets this interface.
         """
         if protocol is None:
             protocol = DEFAULT_PROTOCOL
@@ -204,7 +202,10 @@
             protocol = HIGHEST_PROTOCOL
         elif not 0 <= protocol <= HIGHEST_PROTOCOL:
             raise ValueError("pickle protocol must be <= %d" % HIGHEST_PROTOCOL)
-        self.write = file.write
+        try:
+            self.write = file.write
+        except AttributeError:
+            raise TypeError("file must have a 'write' attribute")
         self.memo = {}
         self.proto = int(protocol)
         self.bin = protocol >= 1
@@ -270,10 +271,10 @@
 
         return GET + repr(i).encode("ascii") + b'\n'
 
-    def save(self, obj):
+    def save(self, obj, save_persistent_id=True):
         # Check for persistent id (defined by a subclass)
         pid = self.persistent_id(obj)
-        if pid:
+        if pid is not None and save_persistent_id:
             self.save_pers(pid)
             return
 
@@ -341,7 +342,7 @@
     def save_pers(self, pid):
         # Save a persistent id reference
         if self.bin:
-            self.save(pid)
+            self.save(pid, save_persistent_id=False)
             self.write(BINPERSID)
         else:
             self.write(PERSID + str(pid).encode("ascii") + b'\n')
@@ -350,13 +351,13 @@
                     listitems=None, dictitems=None, obj=None):
         # This API is called by some subclasses
 
-        # Assert that args is a tuple or None
+        # Assert that args is a tuple
         if not isinstance(args, tuple):
-            raise PicklingError("args from reduce() should be a tuple")
+            raise PicklingError("args from save_reduce() should be a tuple")
 
         # Assert that func is callable
         if not hasattr(func, '__call__'):
-            raise PicklingError("func from reduce should be callable")
+            raise PicklingError("func from save_reduce() should be callable")
 
         save = self.save
         write = self.write
@@ -438,31 +439,6 @@
             self.write(obj and TRUE or FALSE)
     dispatch[bool] = save_bool
 
-    def save_int(self, obj, pack=struct.pack):
-        if self.bin:
-            # If the int is small enough to fit in a signed 4-byte 2's-comp
-            # format, we can store it more efficiently than the general
-            # case.
-            # First one- and two-byte unsigned ints:
-            if obj >= 0:
-                if obj <= 0xff:
-                    self.write(BININT1 + bytes([obj]))
-                    return
-                if obj <= 0xffff:
-                    self.write(BININT2 + bytes([obj&0xff, obj>>8]))
-                    return
-            # Next check for 4-byte signed ints:
-            high_bits = obj >> 31  # note that Python shift sign-extends
-            if high_bits == 0 or high_bits == -1:
-                # All high bits are copies of bit 2**31, so the value
-                # fits in a 4-byte signed int.
-                self.write(BININT + pack("<i", obj))
-                return
-        # Text pickle, or int too big to fit in signed 4-byte format.
-        self.write(INT + repr(obj).encode("ascii") + b'\n')
-    # XXX save_int is merged into save_long
-    # dispatch[int] = save_int
-
     def save_long(self, obj, pack=struct.pack):
         if self.bin:
             # If the int is small enough to fit in a signed 4-byte 2's-comp
@@ -503,7 +479,7 @@
 
     def save_bytes(self, obj, pack=struct.pack):
         if self.proto < 3:
-            self.save_reduce(bytes, (list(obj),))
+            self.save_reduce(bytes, (list(obj),), obj=obj)
             return
         n = len(obj)
         if n < 256:
@@ -579,12 +555,6 @@
 
     dispatch[tuple] = save_tuple
 
-    # save_empty_tuple() isn't used by anything in Python 2.3.  However, I
-    # found a Pickler subclass in Zope3 that calls it, so it's not harmless
-    # to remove it.
-    def save_empty_tuple(self, obj):
-        self.write(EMPTY_TUPLE)
-
     def save_list(self, obj):
         write = self.write
 
@@ -696,7 +666,7 @@
             module = whichmodule(obj, name)
 
         try:
-            __import__(module)
+            __import__(module, level=0)
             mod = sys.modules[module]
             klass = getattr(mod, name)
         except (ImportError, KeyError, AttributeError):
@@ -720,9 +690,19 @@
                 else:
                     write(EXT4 + pack("<i", code))
                 return
+        # Non-ASCII identifiers are supported only with protocols >= 3.
+        if self.proto >= 3:
+            write(GLOBAL + bytes(module, "utf-8") + b'\n' +
+                  bytes(name, "utf-8") + b'\n')
+        else:
+            try:
+                write(GLOBAL + bytes(module, "ascii") + b'\n' +
+                      bytes(name, "ascii") + b'\n')
+            except UnicodeEncodeError:
+                raise PicklingError(
+                    "can't pickle global identifier '%s.%s' using "
+                    "pickle protocol %i" % (module, name, self.proto))
 
-        write(GLOBAL + bytes(module, "utf-8") + b'\n' +
-              bytes(name, "utf-8") + b'\n')
         self.memoize(obj)
 
     dispatch[FunctionType] = save_global
@@ -781,7 +761,7 @@
 
 # Unpickling machinery
 
-class Unpickler:
+class _Unpickler:
 
     def __init__(self, file, *, encoding="ASCII", errors="strict"):
         """This takes a binary file for reading a pickle data stream.
@@ -841,6 +821,9 @@
         while stack[k] is not mark: k = k-1
         return k
 
+    def persistent_load(self, pid):
+        raise UnpickingError("unsupported persistent id encountered")
+
     dispatch = {}
 
     def load_proto(self):
@@ -850,7 +833,7 @@
     dispatch[PROTO[0]] = load_proto
 
     def load_persid(self):
-        pid = self.readline()[:-1]
+        pid = self.readline()[:-1].decode("ascii")
         self.append(self.persistent_load(pid))
     dispatch[PERSID[0]] = load_persid
 
@@ -879,9 +862,9 @@
             val = True
         else:
             try:
-                val = int(data)
+                val = int(data, 0)
             except ValueError:
-                val = int(data)
+                val = int(data, 0)
         self.append(val)
     dispatch[INT[0]] = load_int
 
@@ -933,7 +916,8 @@
                 break
         else:
             raise ValueError("insecure string pickle: %r" % orig)
-        self.append(codecs.escape_decode(rep)[0])
+        self.append(codecs.escape_decode(rep)[0]
+                    .decode(self.encoding, self.errors))
     dispatch[STRING[0]] = load_string
 
     def load_binstring(self):
@@ -975,7 +959,7 @@
     dispatch[TUPLE[0]] = load_tuple
 
     def load_empty_tuple(self):
-        self.stack.append(())
+        self.append(())
     dispatch[EMPTY_TUPLE[0]] = load_empty_tuple
 
     def load_tuple1(self):
@@ -991,11 +975,11 @@
     dispatch[TUPLE3[0]] = load_tuple3
 
     def load_empty_list(self):
-        self.stack.append([])
+        self.append([])
     dispatch[EMPTY_LIST[0]] = load_empty_list
 
     def load_empty_dictionary(self):
-        self.stack.append({})
+        self.append({})
     dispatch[EMPTY_DICT[0]] = load_empty_dictionary
 
     def load_list(self):
@@ -1022,13 +1006,13 @@
     def _instantiate(self, klass, k):
         args = tuple(self.stack[k+1:])
         del self.stack[k:]
-        instantiated = 0
+        instantiated = False
         if (not args and
                 isinstance(klass, type) and
                 not hasattr(klass, "__getinitargs__")):
             value = _EmptyClass()
             value.__class__ = klass
-            instantiated = 1
+            instantiated = True
         if not instantiated:
             try:
                 value = klass(*args)
@@ -1038,8 +1022,8 @@
         self.append(value)
 
     def load_inst(self):
-        module = self.readline()[:-1]
-        name = self.readline()[:-1]
+        module = self.readline()[:-1].decode("ascii")
+        name = self.readline()[:-1].decode("ascii")
         klass = self.find_class(module, name)
         self._instantiate(klass, self.marker())
     dispatch[INST[0]] = load_inst
@@ -1059,8 +1043,8 @@
     dispatch[NEWOBJ[0]] = load_newobj
 
     def load_global(self):
-        module = self.readline()[:-1]
-        name = self.readline()[:-1]
+        module = self.readline()[:-1].decode("utf-8")
+        name = self.readline()[:-1].decode("utf-8")
         klass = self.find_class(module, name)
         self.append(klass)
     dispatch[GLOBAL[0]] = load_global
@@ -1095,11 +1079,7 @@
 
     def find_class(self, module, name):
         # Subclasses may override this
-        if isinstance(module, bytes_types):
-            module = module.decode("utf-8")
-        if isinstance(name, bytes_types):
-            name = name.decode("utf-8")
-        __import__(module)
+        __import__(module, level=0)
         mod = sys.modules[module]
         klass = getattr(mod, name)
         return klass
@@ -1131,31 +1111,33 @@
     dispatch[DUP[0]] = load_dup
 
     def load_get(self):
-        self.append(self.memo[self.readline()[:-1].decode("ascii")])
+        i = int(self.readline()[:-1])
+        self.append(self.memo[i])
     dispatch[GET[0]] = load_get
 
     def load_binget(self):
-        i = ord(self.read(1))
-        self.append(self.memo[repr(i)])
+        i = self.read(1)[0]
+        self.append(self.memo[i])
     dispatch[BINGET[0]] = load_binget
 
     def load_long_binget(self):
         i = mloads(b'i' + self.read(4))
-        self.append(self.memo[repr(i)])
+        self.append(self.memo[i])
     dispatch[LONG_BINGET[0]] = load_long_binget
 
     def load_put(self):
-        self.memo[self.readline()[:-1].decode("ascii")] = self.stack[-1]
+        i = int(self.readline()[:-1])
+        self.memo[i] = self.stack[-1]
     dispatch[PUT[0]] = load_put
 
     def load_binput(self):
-        i = ord(self.read(1))
-        self.memo[repr(i)] = self.stack[-1]
+        i = self.read(1)[0]
+        self.memo[i] = self.stack[-1]
     dispatch[BINPUT[0]] = load_binput
 
     def load_long_binput(self):
         i = mloads(b'i' + self.read(4))
-        self.memo[repr(i)] = self.stack[-1]
+        self.memo[i] = self.stack[-1]
     dispatch[LONG_BINPUT[0]] = load_long_binput
 
     def load_append(self):
@@ -1321,6 +1303,15 @@
         n -= 1 << (nbytes * 8)
     return n
 
+# Use the faster _pickle if possible
+try:
+    from _pickle import *
+except ImportError:
+    Pickler, Unpickler = _Pickler, _Unpickler
+    PickleError = _PickleError
+    PicklingError = _PicklingError
+    UnpicklingError = _UnpicklingError
+
 # Shorthands
 
 def dump(obj, file, protocol=None):
@@ -1333,14 +1324,14 @@
     assert isinstance(res, bytes_types)
     return res
 
-def load(file):
-    return Unpickler(file).load()
+def load(file, *, encoding="ASCII", errors="strict"):
+    return Unpickler(file, encoding=encoding, errors=errors).load()
 
-def loads(s):
+def loads(s, *, encoding="ASCII", errors="strict"):
     if isinstance(s, str):
         raise TypeError("Can't load pickle from unicode string")
     file = io.BytesIO(s)
-    return Unpickler(file).load()
+    return Unpickler(file, encoding=encoding, errors=errors).load()
 
 # Doctest
 
diff --git a/Lib/pickletools.py b/Lib/pickletools.py
index 7bc9c67..1dd45da 100644
--- a/Lib/pickletools.py
+++ b/Lib/pickletools.py
@@ -2079,11 +2079,12 @@
    70: t        TUPLE      (MARK at 49)
    71: p    PUT        5
    74: R    REDUCE
-   75: V    UNICODE    'def'
-   80: p    PUT        6
-   83: s    SETITEM
-   84: a    APPEND
-   85: .    STOP
+   75: p    PUT        6
+   78: V    UNICODE    'def'
+   83: p    PUT        7
+   86: s    SETITEM
+   87: a    APPEND
+   88: .    STOP
 highest protocol among opcodes = 0
 
 Try again with a "binary" pickle.
@@ -2115,11 +2116,12 @@
    49: t            TUPLE      (MARK at 37)
    50: q        BINPUT     5
    52: R        REDUCE
-   53: X        BINUNICODE 'def'
-   61: q        BINPUT     6
-   63: s        SETITEM
-   64: e        APPENDS    (MARK at 3)
-   65: .    STOP
+   53: q        BINPUT     6
+   55: X        BINUNICODE 'def'
+   63: q        BINPUT     7
+   65: s        SETITEM
+   66: e        APPENDS    (MARK at 3)
+   67: .    STOP
 highest protocol among opcodes = 1
 
 Exercise the INST/OBJ/BUILD family.
diff --git a/Lib/test/pickletester.py b/Lib/test/pickletester.py
index 783d361..c9ebdb8 100644
--- a/Lib/test/pickletester.py
+++ b/Lib/test/pickletester.py
@@ -362,7 +362,7 @@
     return x
 
 class AbstractPickleTests(unittest.TestCase):
-    # Subclass must define self.dumps, self.loads, self.error.
+    # Subclass must define self.dumps, self.loads.
 
     _testdata = create_data()
 
@@ -463,8 +463,9 @@
             self.assertEqual(list(x[0].attr.keys()), [1])
             self.assert_(x[0].attr[1] is x)
 
-    def test_garyp(self):
-        self.assertRaises(self.error, self.loads, b'garyp')
+    def test_get(self):
+        self.assertRaises(KeyError, self.loads, b'g0\np0')
+        self.assertEquals(self.loads(b'((Kdtp0\nh\x00l.))'), [(100,), (100,)])
 
     def test_insecure_strings(self):
         # XXX Some of these tests are temporarily disabled
@@ -955,7 +956,7 @@
         f = open(TESTFN, "wb")
         try:
             f.close()
-            self.assertRaises(ValueError, self.module.dump, 123, f)
+            self.assertRaises(ValueError, pickle.dump, 123, f)
         finally:
             os.remove(TESTFN)
 
@@ -964,24 +965,24 @@
         f = open(TESTFN, "wb")
         try:
             f.close()
-            self.assertRaises(ValueError, self.module.dump, 123, f)
+            self.assertRaises(ValueError, pickle.dump, 123, f)
         finally:
             os.remove(TESTFN)
 
     def test_highest_protocol(self):
         # Of course this needs to be changed when HIGHEST_PROTOCOL changes.
-        self.assertEqual(self.module.HIGHEST_PROTOCOL, 3)
+        self.assertEqual(pickle.HIGHEST_PROTOCOL, 3)
 
     def test_callapi(self):
         from io import BytesIO
         f = BytesIO()
         # With and without keyword arguments
-        self.module.dump(123, f, -1)
-        self.module.dump(123, file=f, protocol=-1)
-        self.module.dumps(123, -1)
-        self.module.dumps(123, protocol=-1)
-        self.module.Pickler(f, -1)
-        self.module.Pickler(f, protocol=-1)
+        pickle.dump(123, f, -1)
+        pickle.dump(123, file=f, protocol=-1)
+        pickle.dumps(123, -1)
+        pickle.dumps(123, protocol=-1)
+        pickle.Pickler(f, -1)
+        pickle.Pickler(f, protocol=-1)
 
 class AbstractPersistentPicklerTests(unittest.TestCase):
 
diff --git a/Lib/test/test_pickle.py b/Lib/test/test_pickle.py
index 42fb33e..65a7adc 100644
--- a/Lib/test/test_pickle.py
+++ b/Lib/test/test_pickle.py
@@ -7,37 +7,42 @@
 from test.pickletester import AbstractPickleModuleTests
 from test.pickletester import AbstractPersistentPicklerTests
 
-class PickleTests(AbstractPickleTests, AbstractPickleModuleTests):
+try:
+    import _pickle
+    has_c_implementation = True
+except ImportError:
+    has_c_implementation = False
 
-    module = pickle
-    error = KeyError
 
-    def dumps(self, arg, proto=None):
-        return pickle.dumps(arg, proto)
+class PickleTests(AbstractPickleModuleTests):
+    pass
 
-    def loads(self, buf):
-        return pickle.loads(buf)
 
-class PicklerTests(AbstractPickleTests):
+class PyPicklerTests(AbstractPickleTests):
 
-    error = KeyError
+    pickler = pickle._Pickler
+    unpickler = pickle._Unpickler
 
     def dumps(self, arg, proto=None):
         f = io.BytesIO()
-        p = pickle.Pickler(f, proto)
+        p = self.pickler(f, proto)
         p.dump(arg)
         f.seek(0)
         return bytes(f.read())
 
     def loads(self, buf):
         f = io.BytesIO(buf)
-        u = pickle.Unpickler(f)
+        u = self.unpickler(f)
         return u.load()
 
-class PersPicklerTests(AbstractPersistentPicklerTests):
+
+class PyPersPicklerTests(AbstractPersistentPicklerTests):
+
+    pickler = pickle._Pickler
+    unpickler = pickle._Unpickler
 
     def dumps(self, arg, proto=None):
-        class PersPickler(pickle.Pickler):
+        class PersPickler(self.pickler):
             def persistent_id(subself, obj):
                 return self.persistent_id(obj)
         f = io.BytesIO()
@@ -47,19 +52,29 @@
         return f.read()
 
     def loads(self, buf):
-        class PersUnpickler(pickle.Unpickler):
+        class PersUnpickler(self.unpickler):
             def persistent_load(subself, obj):
                 return self.persistent_load(obj)
         f = io.BytesIO(buf)
         u = PersUnpickler(f)
         return u.load()
 
+
+if has_c_implementation:
+    class CPicklerTests(PyPicklerTests):
+        pickler = _pickle.Pickler
+        unpickler = _pickle.Unpickler
+
+    class CPersPicklerTests(PyPersPicklerTests):
+        pickler = _pickle.Pickler
+        unpickler = _pickle.Unpickler
+
+
 def test_main():
-    support.run_unittest(
-        PickleTests,
-        PicklerTests,
-        PersPicklerTests
-    )
+    tests = [PickleTests, PyPicklerTests, PyPersPicklerTests]
+    if has_c_implementation:
+        tests.extend([CPicklerTests, CPersPicklerTests])
+    support.run_unittest(*tests)
     support.run_doctest(pickle)
 
 if __name__ == "__main__":
diff --git a/Lib/test/test_pickletools.py b/Lib/test/test_pickletools.py
index ccb6c9c..3e701b0 100644
--- a/Lib/test/test_pickletools.py
+++ b/Lib/test/test_pickletools.py
@@ -12,8 +12,6 @@
     def loads(self, buf):
         return pickle.loads(buf)
 
-    module = pickle
-    error = KeyError
 
 def test_main():
     support.run_unittest(OptimizedPickleTests)
diff --git a/Misc/NEWS b/Misc/NEWS
index 17fe598..6bf1441 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -78,6 +78,10 @@
 Library
 -------
 
+- The ``pickle`` module is now automatically use an optimized C
+  implementation of Pickler and Unpickler when available. The
+  ``cPickle`` module is no longer needed.
+
 - Removed the ``htmllib`` and ``sgmllib`` modules.
 
 - The deprecated ``SmartCookie`` and ``SimpleCookie`` classes have
diff --git a/Modules/_pickle.c b/Modules/_pickle.c
new file mode 100644
index 0000000..730c073
--- /dev/null
+++ b/Modules/_pickle.c
@@ -0,0 +1,4546 @@
+#include "Python.h"
+#include "structmember.h"
+
+PyDoc_STRVAR(pickle_module_doc,
+"Optimized C implementation for the Python pickle module.");
+
+/* Bump this when new opcodes are added to the pickle protocol. */
+enum {
+    HIGHEST_PROTOCOL = 3,
+    DEFAULT_PROTOCOL = 3
+};
+
+
+/* Pickle opcodes. These must be kept updated with pickle.py.
+   Extensive docs are in pickletools.py. */
+enum opcode {
+    MARK            = '(',
+    STOP            = '.',
+    POP             = '0',
+    POP_MARK        = '1',
+    DUP             = '2',
+    FLOAT           = 'F',
+    INT             = 'I',
+    BININT          = 'J',
+    BININT1         = 'K',
+    LONG            = 'L',
+    BININT2         = 'M',
+    NONE            = 'N',
+    PERSID          = 'P',
+    BINPERSID       = 'Q',
+    REDUCE          = 'R',
+    STRING          = 'S',
+    BINSTRING       = 'T',
+    SHORT_BINSTRING = 'U',
+    UNICODE         = 'V',
+    BINUNICODE      = 'X',
+    APPEND          = 'a',
+    BUILD           = 'b',
+    GLOBAL          = 'c',
+    DICT            = 'd',
+    EMPTY_DICT      = '}',
+    APPENDS         = 'e',
+    GET             = 'g',
+    BINGET          = 'h',
+    INST            = 'i',
+    LONG_BINGET     = 'j',
+    LIST            = 'l',
+    EMPTY_LIST      = ']',
+    OBJ             = 'o',
+    PUT             = 'p',
+    BINPUT          = 'q',
+    LONG_BINPUT     = 'r',
+    SETITEM         = 's',
+    TUPLE           = 't',
+    EMPTY_TUPLE     = ')',
+    SETITEMS        = 'u',
+    BINFLOAT        = 'G',
+
+    /* Protocol 2. */
+    PROTO       = '\x80',
+    NEWOBJ      = '\x81',
+    EXT1        = '\x82',
+    EXT2        = '\x83',
+    EXT4        = '\x84',
+    TUPLE1      = '\x85',
+    TUPLE2      = '\x86',
+    TUPLE3      = '\x87',
+    NEWTRUE     = '\x88',
+    NEWFALSE    = '\x89',
+    LONG1       = '\x8a',
+    LONG4       = '\x8b',
+
+    /* Protocol 3 (Python 3.x) */
+    BINBYTES       = 'B',
+    SHORT_BINBYTES = 'C',
+};
+
+/* These aren't opcodes -- they're ways to pickle bools before protocol 2
+ * so that unpicklers written before bools were introduced unpickle them
+ * as ints, but unpicklers after can recognize that bools were intended.
+ * Note that protocol 2 added direct ways to pickle bools.
+ */
+#undef TRUE
+#define TRUE  "I01\n"
+#undef FALSE
+#define FALSE "I00\n"
+
+enum {
+   /* Keep in synch with pickle.Pickler._BATCHSIZE.  This is how many elements
+      batch_list/dict() pumps out before doing APPENDS/SETITEMS.  Nothing will
+      break if this gets out of synch with pickle.py, but it's unclear that would
+      help anything either. */
+    BATCHSIZE = 1000,
+
+    /* Nesting limit until Pickler, when running in "fast mode", starts
+       checking for self-referential data-structures. */
+    FAST_NESTING_LIMIT = 50,
+
+    /* Size of the write buffer of Pickler. Higher values will reduce the
+       number of calls to the write() method of the output stream. */
+    WRITE_BUF_SIZE = 256,
+};
+
+/* Exception classes for pickle. These should override the ones defined in
+   pickle.py, when the C-optimized Pickler and Unpickler are used. */
+static PyObject *PickleError;
+static PyObject *PicklingError;
+static PyObject *UnpicklingError;
+
+/* copyreg.dispatch_table, {type_object: pickling_function} */
+static PyObject *dispatch_table;
+/* For EXT[124] opcodes. */
+/* copyreg._extension_registry, {(module_name, function_name): code} */
+static PyObject *extension_registry;
+/* copyreg._inverted_registry, {code: (module_name, function_name)} */
+static PyObject *inverted_registry;
+/* copyreg._extension_cache, {code: object} */
+static PyObject *extension_cache;
+
+/* XXX: Are these really nescessary? */
+/* As the name says, an empty tuple. */
+static PyObject *empty_tuple;
+/* For looking up name pairs in copyreg._extension_registry. */
+static PyObject *two_tuple;
+
+static int
+stack_underflow(void)
+{
+    PyErr_SetString(UnpicklingError, "unpickling stack underflow");
+    return -1;
+}
+
+/* Internal data type used as the unpickling stack. */
+typedef struct {
+    PyObject_HEAD
+    int length;   /* number of initial slots in data currently used */
+    int size;     /* number of slots in data allocated */
+    PyObject **data;
+} Pdata;
+
+static void
+Pdata_dealloc(Pdata *self)
+{
+    int i;
+    PyObject **p;
+
+    for (i = self->length, p = self->data; --i >= 0; p++) {
+        Py_DECREF(*p);
+    }
+    if (self->data)
+        PyMem_Free(self->data);
+    PyObject_Del(self);
+}
+
+static PyTypeObject Pdata_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "_pickle.Pdata",              /*tp_name*/
+    sizeof(Pdata),                /*tp_basicsize*/
+    0,                            /*tp_itemsize*/
+    (destructor)Pdata_dealloc,    /*tp_dealloc*/
+};
+
+static PyObject *
+Pdata_New(void)
+{
+    Pdata *self;
+
+    if (!(self = PyObject_New(Pdata, &Pdata_Type)))
+        return NULL;
+    self->size = 8;
+    self->length = 0;
+    self->data = PyMem_Malloc(self->size * sizeof(PyObject *));
+    if (self->data)
+        return (PyObject *)self;
+    Py_DECREF(self);
+    return PyErr_NoMemory();
+}
+
+
+/* Retain only the initial clearto items.  If clearto >= the current
+ * number of items, this is a (non-erroneous) NOP.
+ */
+static int
+Pdata_clear(Pdata *self, int clearto)
+{
+    int i;
+    PyObject **p;
+
+    if (clearto < 0)
+        return stack_underflow();
+    if (clearto >= self->length)
+        return 0;
+
+    for (i = self->length, p = self->data + clearto; --i >= clearto; p++) {
+        Py_CLEAR(*p);
+    }
+    self->length = clearto;
+
+    return 0;
+}
+
+static int
+Pdata_grow(Pdata *self)
+{
+    int bigger;
+    size_t nbytes;
+    PyObject **tmp;
+
+    bigger = (self->size << 1) + 1;
+    if (bigger <= 0)            /* was 0, or new value overflows */
+        goto nomemory;
+    if ((int)(size_t)bigger != bigger)
+        goto nomemory;
+    nbytes = (size_t)bigger * sizeof(PyObject *);
+    if (nbytes / sizeof(PyObject *) != (size_t)bigger)
+        goto nomemory;
+    tmp = PyMem_Realloc(self->data, nbytes);
+    if (tmp == NULL)
+        goto nomemory;
+    self->data = tmp;
+    self->size = bigger;
+    return 0;
+
+  nomemory:
+    PyErr_NoMemory();
+    return -1;
+}
+
+/* D is a Pdata*.  Pop the topmost element and store it into V, which
+ * must be an lvalue holding PyObject*.  On stack underflow, UnpicklingError
+ * is raised and V is set to NULL.
+ */
+static PyObject *
+Pdata_pop(Pdata *self)
+{
+    if (self->length == 0) {
+        PyErr_SetString(UnpicklingError, "bad pickle data");
+        return NULL;
+    }
+    return self->data[--(self->length)];
+}
+#define PDATA_POP(D, V) do { (V) = Pdata_pop((D)); } while (0)
+
+static int
+Pdata_push(Pdata *self, PyObject *obj)
+{
+    if (self->length == self->size && Pdata_grow(self) < 0) {
+        return -1;
+    }
+    self->data[self->length++] = obj;
+    return 0;
+}
+
+/* Push an object on stack, transferring its ownership to the stack. */
+#define PDATA_PUSH(D, O, ER) do {                               \
+        if (Pdata_push((D), (O)) < 0) return (ER); } while(0)
+
+/* Push an object on stack, adding a new reference to the object. */
+#define PDATA_APPEND(D, O, ER) do {                             \
+        Py_INCREF((O));                                         \
+        if (Pdata_push((D), (O)) < 0) return (ER); } while(0)
+
+static PyObject *
+Pdata_poptuple(Pdata *self, Py_ssize_t start)
+{
+    PyObject *tuple;
+    Py_ssize_t len, i, j;
+
+    len = self->length - start;
+    tuple = PyTuple_New(len);
+    if (tuple == NULL)
+        return NULL;
+    for (i = start, j = 0; j < len; i++, j++)
+        PyTuple_SET_ITEM(tuple, j, self->data[i]);
+
+    self->length = start;
+    return tuple;
+}
+
+static PyObject *
+Pdata_poplist(Pdata *self, Py_ssize_t start)
+{
+    PyObject *list;
+    Py_ssize_t len, i, j;
+
+    len = self->length - start;
+    list = PyList_New(len);
+    if (list == NULL)
+        return NULL;
+    for (i = start, j = 0; j < len; i++, j++)
+        PyList_SET_ITEM(list, j, self->data[i]);
+
+    self->length = start;
+    return list;
+}
+
+typedef struct PicklerObject {
+    PyObject_HEAD
+    PyObject *write;            /* write() method of the output stream */
+    PyObject *memo;             /* Memo dictionary, keep track of the seen
+                                   objects to support self-referential objects
+                                   pickling.  */
+    PyObject *pers_func;        /* persistent_id() method, can be NULL */
+    PyObject *arg;
+    int proto;                  /* Pickle protocol number, >= 0 */
+    int bin;                    /* Boolean, true if proto > 0 */
+    int nesting;                /* Current nesting level, this is to guard
+                                   save() from going into infinite recursion
+                                   and segfaulting. */
+    int buf_size;               /* Size of the current buffered pickle data */
+    char *write_buf;            /* Write buffer, this is to avoid calling the
+                                   write() method of the output stream too
+                                   often. */
+    int fast;                   /* Enable fast mode if set to a true value.
+                                   The fast mode disable the usage of memo,
+                                   therefore speeding the pickling process by
+                                   not generating superfluous PUT opcodes. It
+                                   should not be used if with self-referential
+                                   objects. */
+    int fast_nesting;
+    PyObject *fast_memo;
+} PicklerObject;
+
+typedef struct UnpicklerObject {
+    PyObject_HEAD
+    Pdata *stack;               /* Pickle data stack, store unpickled objects. */
+    PyObject *readline;         /* readline() method of the output stream */
+    PyObject *read;             /* read() method of the output stream */
+    PyObject *memo;             /* Memo dictionary, provide the objects stored
+                                   using the PUT opcodes. */
+    PyObject *arg;
+    PyObject *pers_func;        /* persistent_load() method, can be NULL. */
+    PyObject *last_string;      /* Reference to the last string read by the
+                                   readline() method.  */
+    char *buffer;               /* Reading buffer. */
+    char *encoding;             /* Name of the encoding to be used for
+                                   decoding strings pickled using Python
+                                   2.x. The default value is "ASCII" */
+    char *errors;               /* Name of errors handling scheme to used when
+                                   decoding strings. The default value is
+                                   "strict". */
+    int *marks;                 /* Mark stack, used for unpickling container
+                                   objects. */
+    Py_ssize_t num_marks;       /* Number of marks in the mark stack. */
+    Py_ssize_t marks_size;      /* Current allocated size of the mark stack. */
+} UnpicklerObject;
+
+/* Forward declarations */
+static int save(PicklerObject *, PyObject *, int);
+static int save_reduce(PicklerObject *, PyObject *, PyObject *);
+static PyTypeObject Pickler_Type;
+static PyTypeObject Unpickler_Type;
+
+
+/* Helpers for creating the argument tuple passed to functions. This has the
+   performance advantage of calling PyTuple_New() only once. */
+
+#define ARG_TUP(self, obj) do {                             \
+        if ((self)->arg || ((self)->arg=PyTuple_New(1))) {  \
+            Py_XDECREF(PyTuple_GET_ITEM((self)->arg, 0));   \
+            PyTuple_SET_ITEM((self)->arg, 0, (obj));        \
+        }                                                   \
+        else {                                              \
+            Py_DECREF((obj));                               \
+        }                                                   \
+    } while (0)
+
+#define FREE_ARG_TUP(self) do {                 \
+        if ((self)->arg->ob_refcnt > 1)         \
+            Py_CLEAR((self)->arg);              \
+    } while (0)
+
+/* A temporary cleaner API for fast single argument function call.
+
+   XXX: Does caching the argument tuple provides any real performance benefits?
+
+   A quick benchmark, on a 2.0GHz Athlon64 3200+ running Linux 2.6.24 with
+   glibc 2.7, tells me that it takes roughly 20,000,000 PyTuple_New(1) calls
+   when the tuple is retrieved from the freelist (i.e, call PyTuple_New() then
+   immediately DECREF it) and 1,200,000 calls when allocating brand new tuples
+   (i.e, call PyTuple_New() and store the returned value in an array), to save
+   one second (wall clock time). Either ways, the loading time a pickle stream
+   large enough to generate this number of calls would be massively
+   overwhelmed by other factors, like I/O throughput, the GC traversal and
+   object allocation overhead. So, I really doubt these functions provide any
+   real benefits.
+
+   On the other hand, oprofile reports that pickle spends a lot of time in
+   these functions. But, that is probably more related to the function call
+   overhead, than the argument tuple allocation.
+
+   XXX: And, what is the reference behavior of these? Steal, borrow? At first
+   glance, it seems to steal the reference of 'arg' and borrow the reference
+   of 'func'.
+ */
+static PyObject *
+pickler_call(PicklerObject *self, PyObject *func, PyObject *arg)
+{
+    PyObject *result = NULL;
+
+    ARG_TUP(self, arg);
+    if (self->arg) {
+        result = PyObject_Call(func, self->arg, NULL);
+        FREE_ARG_TUP(self);
+    }
+    return result;
+}
+
+static PyObject *
+unpickler_call(UnpicklerObject *self, PyObject *func, PyObject *arg)
+{
+    PyObject *result = NULL;
+
+    ARG_TUP(self, arg);
+    if (self->arg) {
+        result = PyObject_Call(func, self->arg, NULL);
+        FREE_ARG_TUP(self);
+    }
+    return result;
+}
+
+static Py_ssize_t
+pickler_write(PicklerObject *self, const char *s, Py_ssize_t n)
+{
+    PyObject *data, *result;
+
+    if (s == NULL) {
+        if (!(self->buf_size))
+            return 0;
+        data = PyBytes_FromStringAndSize(self->write_buf, self->buf_size);
+        if (data == NULL)
+            return -1;
+    }
+    else {
+        if (self->buf_size && (n + self->buf_size) > WRITE_BUF_SIZE) {
+            if (pickler_write(self, NULL, 0) < 0)
+                return -1;
+        }
+
+        if (n > WRITE_BUF_SIZE) {
+            if (!(data = PyBytes_FromStringAndSize(s, n)))
+                return -1;
+        }
+        else {
+            memcpy(self->write_buf + self->buf_size, s, n);
+            self->buf_size += n;
+            return n;
+        }
+    }
+
+    /* object with write method */
+    result = pickler_call(self, self->write, data);
+    if (result == NULL)
+        return -1;
+
+    Py_DECREF(result);
+    self->buf_size = 0;
+    return n;
+}
+
+/* XXX: These read/readline functions ought to be optimized. Buffered I/O
+   might help a lot, especially with the new (but much slower) io library.
+   On the other hand, the added complexity might not worth it.
+ */
+
+/* Read at least n characters from the input stream and set s to the current
+   reading position. */
+static Py_ssize_t
+unpickler_read(UnpicklerObject *self, char **s, Py_ssize_t n)
+{
+    PyObject *len;
+    PyObject *data;
+
+    len = PyLong_FromSsize_t(n);
+    if (len == NULL)
+        return -1;
+
+    data = unpickler_call(self, self->read, len);
+    if (data == NULL)
+        return -1;
+
+    /* XXX: Should bytearray be supported too? */
+    if (!PyBytes_Check(data)) {
+        PyErr_SetString(PyExc_ValueError,
+                        "read() from the underlying stream did not"
+                        "return bytes");
+        return -1;
+    }
+
+    Py_XDECREF(self->last_string);
+    self->last_string = data;
+
+    if (!(*s = PyBytes_AS_STRING(data)))
+        return -1;
+
+    return n;
+}
+
+static Py_ssize_t
+unpickler_readline(UnpicklerObject *self, char **s)
+{
+    PyObject *data;
+
+    data = PyObject_CallObject(self->readline, empty_tuple);
+    if (data == NULL)
+        return -1;
+
+    /* XXX: Should bytearray be supported too? */
+    if (!PyBytes_Check(data)) {
+        PyErr_SetString(PyExc_ValueError,
+                        "readline() from the underlying stream did not"
+                        "return bytes");
+        return -1;
+    }
+
+    Py_XDECREF(self->last_string);
+    self->last_string = data;
+
+    if (!(*s = PyBytes_AS_STRING(data)))
+        return -1;
+
+    return PyBytes_GET_SIZE(data);
+}
+
+/* Generate a GET opcode for an object stored in the memo. The 'key' argument
+   should be the address of the object as returned by PyLong_FromVoidPtr(). */
+static int
+memo_get(PicklerObject *self, PyObject *key)
+{
+    PyObject *value;
+    PyObject *memo_id;
+    long x;
+    char pdata[30];
+    int len;
+
+    value = PyDict_GetItemWithError(self->memo, key);
+    if (value == NULL) {
+        if (!PyErr_Occurred())
+            PyErr_SetObject(PyExc_KeyError, key);
+        return -1;
+    }
+
+    memo_id = PyTuple_GetItem(value, 0);
+    if (memo_id == NULL)
+        return -1;
+
+    if (!PyLong_Check(memo_id)) {
+        PyErr_SetString(PicklingError, "memo id must be an integer");
+        return -1;
+    }
+    x = PyLong_AsLong(memo_id);
+    if (x == -1 && PyErr_Occurred())
+        return -1;
+
+    if (!self->bin) {
+        pdata[0] = GET;
+        PyOS_snprintf(pdata + 1, sizeof(pdata) - 1, "%ld\n", x);
+        len = (int)strlen(pdata);
+    }
+    else {
+        if (x < 256) {
+            pdata[0] = BINGET;
+            pdata[1] = (unsigned char)(x & 0xff);
+            len = 2;
+        }
+        else if (x <= 0xffffffffL) {
+            pdata[0] = LONG_BINGET;
+            pdata[1] = (unsigned char)(x & 0xff);
+            pdata[2] = (unsigned char)((x >> 8) & 0xff);
+            pdata[3] = (unsigned char)((x >> 16) & 0xff);
+            pdata[4] = (unsigned char)((x >> 24) & 0xff);
+            len = 5;
+        }
+        else { /* unlikely */
+            PyErr_SetString(PicklingError,
+                            "memo id too large for LONG_BINGET");
+            return -1;
+        }
+    }
+
+    if (pickler_write(self, pdata, len) < 0)
+        return -1;
+
+    return 0;
+}
+
+/* Store an object in the memo, assign it a new unique ID based on the number
+   of objects currently stored in the memo and generate a PUT opcode. */
+static int
+memo_put(PicklerObject *self, PyObject *obj)
+{
+    PyObject *key = NULL;
+    PyObject *memo_id = NULL;
+    PyObject *tuple = NULL;
+    long x;
+    char pdata[30];
+    int len;
+    int status = 0;
+
+    if (self->fast)
+        return 0;
+
+    key = PyLong_FromVoidPtr(obj);
+    if (key == NULL)
+        goto error;
+    if ((x = PyDict_Size(self->memo)) < 0)
+        goto error;
+    memo_id = PyLong_FromLong(x);
+    if (memo_id == NULL)
+        goto error;
+    tuple = PyTuple_New(2);
+    if (tuple == NULL)
+        goto error;
+
+    Py_INCREF(memo_id);
+    PyTuple_SET_ITEM(tuple, 0, memo_id);
+    Py_INCREF(obj);
+    PyTuple_SET_ITEM(tuple, 1, obj);
+    if (PyDict_SetItem(self->memo, key, tuple) < 0)
+        goto error;
+
+    if (!self->bin) {
+        pdata[0] = PUT;
+        PyOS_snprintf(pdata + 1, sizeof(pdata) - 1, "%ld\n", x);
+        len = strlen(pdata);
+    }
+    else {
+        if (x < 256) {
+            pdata[0] = BINPUT;
+            pdata[1] = x;
+            len = 2;
+        }
+        else if (x <= 0xffffffffL) {
+            pdata[0] = LONG_BINPUT;
+            pdata[1] = (unsigned char)(x & 0xff);
+            pdata[2] = (unsigned char)((x >> 8) & 0xff);
+            pdata[3] = (unsigned char)((x >> 16) & 0xff);
+            pdata[4] = (unsigned char)((x >> 24) & 0xff);
+            len = 5;
+        }
+        else { /* unlikely */
+            PyErr_SetString(PicklingError,
+                            "memo id too large for LONG_BINPUT");
+            return -1;
+        }
+    }
+
+    if (pickler_write(self, pdata, len) < 0)
+        goto error;
+
+    if (0) {
+  error:
+        status = -1;
+    }
+
+    Py_XDECREF(key);
+    Py_XDECREF(memo_id);
+    Py_XDECREF(tuple);
+
+    return status;
+}
+
+static PyObject *
+whichmodule(PyObject *global, PyObject *global_name)
+{
+    Py_ssize_t i, j;
+    static PyObject *module_str = NULL;
+    static PyObject *main_str = NULL;
+    PyObject *module_name;
+    PyObject *modules_dict;
+    PyObject *module;
+    PyObject *obj;
+
+    if (module_str == NULL) {
+        module_str = PyUnicode_InternFromString("__module__");
+        if (module_str == NULL)
+            return NULL;
+        main_str = PyUnicode_InternFromString("__main__");
+        if (main_str == NULL)
+            return NULL;
+    }
+
+    module_name = PyObject_GetAttr(global, module_str);
+
+    /* In some rare cases (e.g., random.getrandbits), __module__ can be
+       None. If it is so, then search sys.modules for the module of
+       global.  */
+    if (module_name == Py_None) {
+        Py_DECREF(module_name);
+        goto search;
+    }
+
+    if (module_name) {
+        return module_name;
+    }
+    if (PyErr_ExceptionMatches(PyExc_AttributeError))
+        PyErr_Clear();
+    else
+        return NULL;
+
+  search:
+    modules_dict = PySys_GetObject("modules");
+    if (modules_dict == NULL)
+        return NULL;
+
+    i = 0;
+    module_name = NULL;
+    while ((j = PyDict_Next(modules_dict, &i, &module_name, &module))) {
+        if (PyObject_Compare(module_name, main_str) == 0)
+            continue;
+
+        obj = PyObject_GetAttr(module, global_name);
+        if (obj == NULL) {
+            if (PyErr_ExceptionMatches(PyExc_AttributeError))
+                PyErr_Clear();
+            else
+                return NULL;
+            continue;
+        }
+
+        if (obj != global) {
+            Py_DECREF(obj);
+            continue;
+        }
+
+        Py_DECREF(obj);
+        break;
+    }
+
+    /* If no module is found, use __main__. */
+    if (!j) {
+        module_name = main_str;
+    }
+
+    Py_INCREF(module_name);
+    return module_name;
+}
+
+/* fast_save_enter() and fast_save_leave() are guards against recursive
+   objects when Pickler is used with the "fast mode" (i.e., with object
+   memoization disabled). If the nesting of a list or dict object exceed
+   FAST_NESTING_LIMIT, these guards will start keeping an internal
+   reference to the seen list or dict objects and check whether these objects
+   are recursive. These are not strictly necessary, since save() has a
+   hard-coded recursion limit, but they give a nicer error message than the
+   typical RuntimeError. */
+static int
+fast_save_enter(PicklerObject *self, PyObject *obj)
+{
+    /* if fast_nesting < 0, we're doing an error exit. */
+    if (++self->fast_nesting >= FAST_NESTING_LIMIT) {
+        PyObject *key = NULL;
+        if (self->fast_memo == NULL) {
+            self->fast_memo = PyDict_New();
+            if (self->fast_memo == NULL) {
+                self->fast_nesting = -1;
+                return 0;
+            }
+        }
+        key = PyLong_FromVoidPtr(obj);
+        if (key == NULL)
+            return 0;
+        if (PyDict_GetItem(self->fast_memo, key)) {
+            Py_DECREF(key);
+            PyErr_Format(PyExc_ValueError,
+                         "fast mode: can't pickle cyclic objects "
+                         "including object type %.200s at %p",
+                         obj->ob_type->tp_name, obj);
+            self->fast_nesting = -1;
+            return 0;
+        }
+        if (PyDict_SetItem(self->fast_memo, key, Py_None) < 0) {
+            Py_DECREF(key);
+            self->fast_nesting = -1;
+            return 0;
+        }
+        Py_DECREF(key);
+    }
+    return 1;
+}
+
+static int
+fast_save_leave(PicklerObject *self, PyObject *obj)
+{
+    if (self->fast_nesting-- >= FAST_NESTING_LIMIT) {
+        PyObject *key = PyLong_FromVoidPtr(obj);
+        if (key == NULL)
+            return 0;
+        if (PyDict_DelItem(self->fast_memo, key) < 0) {
+            Py_DECREF(key);
+            return 0;
+        }
+        Py_DECREF(key);
+    }
+    return 1;
+}
+
+static int
+save_none(PicklerObject *self, PyObject *obj)
+{
+    const char none_op = NONE;
+    if (pickler_write(self, &none_op, 1) < 0)
+        return -1;
+
+    return 0;
+}
+
+static int
+save_bool(PicklerObject *self, PyObject *obj)
+{
+    static const char *buf[2] = { FALSE, TRUE };
+    const char len[2] = {sizeof(FALSE) - 1, sizeof(TRUE) - 1};
+    int p = (obj == Py_True);
+
+    if (self->proto >= 2) {
+        const char bool_op = p ? NEWTRUE : NEWFALSE;
+        if (pickler_write(self, &bool_op, 1) < 0)
+            return -1;
+    }
+    else if (pickler_write(self, buf[p], len[p]) < 0)
+        return -1;
+
+    return 0;
+}
+
+static int
+save_int(PicklerObject *self, long x)
+{
+    char pdata[32];
+    int len = 0;
+
+    if (!self->bin
+#if SIZEOF_LONG > 4
+        || x > 0x7fffffffL || x < -0x80000000L
+#endif
+        ) {
+        /* Text-mode pickle, or long too big to fit in the 4-byte
+         * signed BININT format:  store as a string.
+         */
+        pdata[0] = LONG;        /* use LONG for consistence with pickle.py */
+        PyOS_snprintf(pdata + 1, sizeof(pdata) - 1, "%ld\n", x);
+        if (pickler_write(self, pdata, strlen(pdata)) < 0)
+            return -1;
+    }
+    else {
+        /* Binary pickle and x fits in a signed 4-byte int. */
+        pdata[1] = (unsigned char)(x & 0xff);
+        pdata[2] = (unsigned char)((x >> 8) & 0xff);
+        pdata[3] = (unsigned char)((x >> 16) & 0xff);
+        pdata[4] = (unsigned char)((x >> 24) & 0xff);
+
+        if ((pdata[4] == 0) && (pdata[3] == 0)) {
+            if (pdata[2] == 0) {
+                pdata[0] = BININT1;
+                len = 2;
+            }
+            else {
+                pdata[0] = BININT2;
+                len = 3;
+            }
+        }
+        else {
+            pdata[0] = BININT;
+            len = 5;
+        }
+
+        if (pickler_write(self, pdata, len) < 0)
+            return -1;
+    }
+
+    return 0;
+}
+
+static int
+save_long(PicklerObject *self, PyObject *obj)
+{
+    PyObject *repr = NULL;
+    Py_ssize_t size;
+    long val = PyLong_AsLong(obj);
+    int status = 0;
+
+    const char long_op = LONG;
+
+    if (val == -1 && PyErr_Occurred()) {
+        /* out of range for int pickling */
+        PyErr_Clear();
+    }
+    else
+        return save_int(self, val);
+
+    if (self->proto >= 2) {
+        /* Linear-time pickling. */
+        size_t nbits;
+        size_t nbytes;
+        unsigned char *pdata;
+        char header[5];
+        int i;
+        int sign = _PyLong_Sign(obj);
+
+        if (sign == 0) {
+            header[0] = LONG1;
+            header[1] = 0;      /* It's 0 -- an empty bytestring. */
+            if (pickler_write(self, header, 2) < 0)
+                goto error;
+            return 0;
+        }
+        nbits = _PyLong_NumBits(obj);
+        if (nbits == (size_t)-1 && PyErr_Occurred())
+            goto error;
+        /* How many bytes do we need?  There are nbits >> 3 full
+         * bytes of data, and nbits & 7 leftover bits.  If there
+         * are any leftover bits, then we clearly need another
+         * byte.  Wnat's not so obvious is that we *probably*
+         * need another byte even if there aren't any leftovers:
+         * the most-significant bit of the most-significant byte
+         * acts like a sign bit, and it's usually got a sense
+         * opposite of the one we need.  The exception is longs
+         * of the form -(2**(8*j-1)) for j > 0.  Such a long is
+         * its own 256's-complement, so has the right sign bit
+         * even without the extra byte.  That's a pain to check
+         * for in advance, though, so we always grab an extra
+         * byte at the start, and cut it back later if possible.
+         */
+        nbytes = (nbits >> 3) + 1;
+        if (nbytes > INT_MAX) {
+            PyErr_SetString(PyExc_OverflowError,
+                            "long too large to pickle");
+            goto error;
+        }
+        repr = PyUnicode_FromStringAndSize(NULL, (int)nbytes);
+        if (repr == NULL)
+            goto error;
+        pdata = (unsigned char *)PyUnicode_AsString(repr);
+        i = _PyLong_AsByteArray((PyLongObject *)obj,
+                                pdata, nbytes,
+                                1 /* little endian */ , 1 /* signed */ );
+        if (i < 0)
+            goto error;
+        /* If the long is negative, this may be a byte more than
+         * needed.  This is so iff the MSB is all redundant sign
+         * bits.
+         */
+        if (sign < 0 &&
+            nbytes > 1 && 
+            pdata[nbytes - 1] == 0xff &&
+            (pdata[nbytes - 2] & 0x80) != 0) {
+            nbytes--;
+        }
+
+        if (nbytes < 256) {
+            header[0] = LONG1;
+            header[1] = (unsigned char)nbytes;
+            size = 2;
+        }
+        else {
+            header[0] = LONG4;
+            size = (int)nbytes;
+            for (i = 1; i < 5; i++) {
+                header[i] = (unsigned char)(size & 0xff);
+                size >>= 8;
+            }
+            size = 5;
+        }
+        if (pickler_write(self, header, size) < 0 ||
+            pickler_write(self, (char *)pdata, (int)nbytes) < 0)
+            goto error;
+    }
+    else {
+        char *string;
+
+        /* proto < 2:  write the repr and newline.  This is quadratic-time
+           (in the number of digits), in both directions. */
+
+        repr = PyObject_Repr(obj);
+        if (repr == NULL)
+            goto error;
+
+        string = PyUnicode_AsStringAndSize(repr, &size);
+        if (string == NULL)
+            goto error;
+
+        if (pickler_write(self, &long_op, 1) < 0 ||
+            pickler_write(self, string, size) < 0 ||
+            pickler_write(self, "\n", 1) < 0)
+            goto error;
+    }
+
+    if (0) {
+  error:
+      status = -1;
+    }
+    Py_XDECREF(repr);
+
+    return status;
+}
+
+static int
+save_float(PicklerObject *self, PyObject *obj)
+{
+    double x = PyFloat_AS_DOUBLE((PyFloatObject *)obj);
+
+    if (self->bin) {
+        char pdata[9];
+        pdata[0] = BINFLOAT;
+        if (_PyFloat_Pack8(x, (unsigned char *)&pdata[1], 0) < 0)
+            return -1;
+        if (pickler_write(self, pdata, 9) < 0)
+            return -1;
+    }
+    else {
+        char pdata[250];
+        pdata[0] = FLOAT;
+        PyOS_ascii_formatd(pdata + 1, sizeof(pdata) - 2, "%.17g", x);
+        /* Extend the formatted string with a newline character */
+        strcat(pdata, "\n");
+
+        if (pickler_write(self, pdata, strlen(pdata)) < 0)
+            return -1;
+    }
+
+    return 0;
+}
+
+static int
+save_bytes(PicklerObject *self, PyObject *obj)
+{
+    if (self->proto < 3) {
+        /* Older pickle protocols do not have an opcode for pickling bytes
+           objects. Therefore, we need to fake the copy protocol (i.e.,
+           the __reduce__ method) to permit bytes object unpickling. */
+        PyObject *reduce_value = NULL;
+        PyObject *bytelist = NULL;
+        int status;
+
+        bytelist = PySequence_List(obj);
+        if (bytelist == NULL)
+            return -1;
+
+        reduce_value = Py_BuildValue("(O(O))", (PyObject *)&PyBytes_Type,
+                                     bytelist);
+        if (reduce_value == NULL) {
+            Py_DECREF(bytelist);
+            return -1;
+        }
+
+        /* save_reduce() will memoize the object automatically. */
+        status = save_reduce(self, reduce_value, obj);
+        Py_DECREF(reduce_value);
+        Py_DECREF(bytelist);
+        return status;
+    }
+    else {
+        Py_ssize_t size;
+        char header[5];
+        int len;
+
+        size = PyBytes_Size(obj);
+        if (size < 0)
+            return -1;
+
+        if (size < 256) {
+            header[0] = SHORT_BINBYTES;
+            header[1] = (unsigned char)size;
+            len = 2;
+        }
+        else if (size <= 0xffffffffL) {
+            header[0] = BINBYTES;
+            header[1] = (unsigned char)(size & 0xff);
+            header[2] = (unsigned char)((size >> 8) & 0xff);
+            header[3] = (unsigned char)((size >> 16) & 0xff);
+            header[4] = (unsigned char)((size >> 24) & 0xff);
+            len = 5;
+        }
+        else {
+            return -1;          /* string too large */
+        }
+
+        if (pickler_write(self, header, len) < 0)
+            return -1;
+
+        if (pickler_write(self, PyBytes_AS_STRING(obj), size) < 0)
+            return -1;
+
+        if (memo_put(self, obj) < 0)
+            return -1;
+
+        return 0;
+    }
+}
+
+/* A copy of PyUnicode_EncodeRawUnicodeEscape() that also translates
+   backslash and newline characters to \uXXXX escapes. */
+static PyObject *
+raw_unicode_escape(const Py_UNICODE *s, Py_ssize_t size)
+{
+    PyObject *repr, *result;
+    char *p;
+    char *q;
+
+    static const char *hexdigits = "0123456789abcdef";
+
+#ifdef Py_UNICODE_WIDE
+    repr = PyBytes_FromStringAndSize(NULL, 10 * size);
+#else
+    repr = PyBytes_FromStringAndSize(NULL, 6 * size);
+#endif
+    if (repr == NULL)
+        return NULL;
+    if (size == 0)
+        goto done;
+
+    p = q = PyBytes_AS_STRING(repr);
+    while (size-- > 0) {
+        Py_UNICODE ch = *s++;
+#ifdef Py_UNICODE_WIDE
+        /* Map 32-bit characters to '\Uxxxxxxxx' */
+        if (ch >= 0x10000) {
+            *p++ = '\\';
+            *p++ = 'U';
+            *p++ = hexdigits[(ch >> 28) & 0xf];
+            *p++ = hexdigits[(ch >> 24) & 0xf];
+            *p++ = hexdigits[(ch >> 20) & 0xf];
+            *p++ = hexdigits[(ch >> 16) & 0xf];
+            *p++ = hexdigits[(ch >> 12) & 0xf];
+            *p++ = hexdigits[(ch >> 8) & 0xf];
+            *p++ = hexdigits[(ch >> 4) & 0xf];
+            *p++ = hexdigits[ch & 15];
+        }
+        else
+#endif
+        /* Map 16-bit characters to '\uxxxx' */
+        if (ch >= 256 || ch == '\\' || ch == '\n') {
+            *p++ = '\\';
+            *p++ = 'u';
+            *p++ = hexdigits[(ch >> 12) & 0xf];
+            *p++ = hexdigits[(ch >> 8) & 0xf];
+            *p++ = hexdigits[(ch >> 4) & 0xf];
+            *p++ = hexdigits[ch & 15];
+        }
+	/* Copy everything else as-is */
+        else
+            *p++ = (char) ch;
+    }
+    size = p - q;
+
+  done:
+    result = PyBytes_FromStringAndSize(PyBytes_AS_STRING(repr), size);
+    Py_DECREF(repr);
+    return result;
+}
+
+static int
+save_unicode(PicklerObject *self, PyObject *obj)
+{
+    Py_ssize_t size;
+    PyObject *encoded = NULL;
+
+    if (self->bin) {
+        char pdata[5];
+
+        encoded = PyUnicode_AsUTF8String(obj);
+        if (encoded == NULL)
+            goto error;
+
+        size = PyBytes_GET_SIZE(encoded);
+        if (size < 0 || size > 0xffffffffL)
+            goto error;          /* string too large */
+
+        pdata[0] = BINUNICODE;
+        pdata[1] = (unsigned char)(size & 0xff);
+        pdata[2] = (unsigned char)((size >> 8) & 0xff);
+        pdata[3] = (unsigned char)((size >> 16) & 0xff);
+        pdata[4] = (unsigned char)((size >> 24) & 0xff);
+
+        if (pickler_write(self, pdata, 5) < 0)
+            goto error;
+
+        if (pickler_write(self, PyBytes_AS_STRING(encoded), size) < 0)
+            goto error;
+    }
+    else {
+        const char unicode_op = UNICODE;
+
+        encoded = raw_unicode_escape(PyUnicode_AS_UNICODE(obj),
+                                     PyUnicode_GET_SIZE(obj));
+        if (encoded == NULL)
+            goto error;
+
+        if (pickler_write(self, &unicode_op, 1) < 0)
+            goto error;
+
+        size = PyBytes_GET_SIZE(encoded);
+        if (pickler_write(self, PyBytes_AS_STRING(encoded), size) < 0)
+            goto error;
+
+        if (pickler_write(self, "\n", 1) < 0)
+            goto error;
+    }
+    if (memo_put(self, obj) < 0)
+        goto error;
+
+    Py_DECREF(encoded);
+    return 0;
+
+  error:
+    Py_XDECREF(encoded);
+    return -1;
+}
+
+/* A helper for save_tuple.  Push the len elements in tuple t on the stack. */
+static int
+store_tuple_elements(PicklerObject *self, PyObject *t, int len)
+{
+    int i;
+
+    assert(PyTuple_Size(t) == len);
+
+    for (i = 0; i < len; i++) {
+        PyObject *element = PyTuple_GET_ITEM(t, i);
+
+        if (element == NULL)
+            return -1;
+        if (save(self, element, 0) < 0)
+            return -1;
+    }
+
+    return 0;
+}
+
+/* Tuples are ubiquitous in the pickle protocols, so many techniques are
+ * used across protocols to minimize the space needed to pickle them.
+ * Tuples are also the only builtin immutable type that can be recursive
+ * (a tuple can be reached from itself), and that requires some subtle
+ * magic so that it works in all cases.  IOW, this is a long routine.
+ */
+static int
+save_tuple(PicklerObject *self, PyObject *obj)
+{
+    PyObject *memo_key = NULL;
+    int len, i;
+    int status = 0;
+
+    const char mark_op = MARK;
+    const char tuple_op = TUPLE;
+    const char pop_op = POP;
+    const char pop_mark_op = POP_MARK;
+    const char len2opcode[] = {EMPTY_TUPLE, TUPLE1, TUPLE2, TUPLE3};
+
+    if ((len = PyTuple_Size(obj)) < 0)
+        return -1;
+
+    if (len == 0) {
+        char pdata[2];
+
+        if (self->proto) {
+            pdata[0] = EMPTY_TUPLE;
+            len = 1;
+        }
+        else {
+            pdata[0] = MARK;
+            pdata[1] = TUPLE;
+            len = 2;
+        }
+        if (pickler_write(self, pdata, len) < 0)
+            return -1;
+        return 0;
+    }
+
+    /* id(tuple) isn't in the memo now.  If it shows up there after
+     * saving the tuple elements, the tuple must be recursive, in
+     * which case we'll pop everything we put on the stack, and fetch
+     * its value from the memo.
+     */
+    memo_key = PyLong_FromVoidPtr(obj);
+    if (memo_key == NULL)
+        return -1;
+
+    if (len <= 3 && self->proto >= 2) {
+        /* Use TUPLE{1,2,3} opcodes. */
+        if (store_tuple_elements(self, obj, len) < 0)
+            goto error;
+
+        if (PyDict_GetItem(self->memo, memo_key)) {
+            /* pop the len elements */
+            for (i = 0; i < len; i++)
+                if (pickler_write(self, &pop_op, 1) < 0)
+                    goto error;
+            /* fetch from memo */
+            if (memo_get(self, memo_key) < 0)
+                goto error;
+
+            Py_DECREF(memo_key);
+            return 0;
+        }
+        else { /* Not recursive. */
+            if (pickler_write(self, len2opcode + len, 1) < 0)
+                goto error;
+        }
+        goto memoize;
+    }
+
+    /* proto < 2 and len > 0, or proto >= 2 and len > 3.
+     * Generate MARK e1 e2 ... TUPLE
+     */
+    if (pickler_write(self, &mark_op, 1) < 0)
+        goto error;
+
+    if (store_tuple_elements(self, obj, len) < 0)
+        goto error;
+
+    if (PyDict_GetItem(self->memo, memo_key)) {
+        /* pop the stack stuff we pushed */
+        if (self->bin) {
+            if (pickler_write(self, &pop_mark_op, 1) < 0)
+                goto error;
+        }
+        else {
+            /* Note that we pop one more than len, to remove
+             * the MARK too.
+             */
+            for (i = 0; i <= len; i++)
+                if (pickler_write(self, &pop_op, 1) < 0)
+                    goto error;
+        }
+        /* fetch from memo */
+        if (memo_get(self, memo_key) < 0)
+            goto error;
+
+        Py_DECREF(memo_key);
+        return 0;
+    }
+    else { /* Not recursive. */
+        if (pickler_write(self, &tuple_op, 1) < 0)
+            goto error;
+    }
+
+  memoize:
+    if (memo_put(self, obj) < 0)
+        goto error;
+
+    if (0) {
+  error:
+        status = -1;
+    }
+
+    Py_DECREF(memo_key);
+    return status;
+}
+
+/* iter is an iterator giving items, and we batch up chunks of
+ *     MARK item item ... item APPENDS
+ * opcode sequences.  Calling code should have arranged to first create an
+ * empty list, or list-like object, for the APPENDS to operate on.
+ * Returns 0 on success, <0 on error.
+ */
+static int
+batch_list(PicklerObject *self, PyObject *iter)
+{
+    PyObject *obj;
+    PyObject *slice[BATCHSIZE];
+    int i, n;
+
+    const char mark_op = MARK;
+    const char append_op = APPEND;
+    const char appends_op = APPENDS;
+
+    assert(iter != NULL);
+
+    /* XXX: I think this function could be made faster by avoiding the
+       iterator interface and fetching objects directly from list using
+       PyList_GET_ITEM.
+    */
+
+    if (self->proto == 0) {
+        /* APPENDS isn't available; do one at a time. */
+        for (;;) {
+            obj = PyIter_Next(iter);
+            if (obj == NULL) {
+                if (PyErr_Occurred())
+                    return -1;
+                break;
+            }
+            i = save(self, obj, 0);
+            Py_DECREF(obj);
+            if (i < 0)
+                return -1;
+            if (pickler_write(self, &append_op, 1) < 0)
+                return -1;
+        }
+        return 0;
+    }
+
+    /* proto > 0:  write in batches of BATCHSIZE. */
+    do {
+        /* Get next group of (no more than) BATCHSIZE elements. */
+        for (n = 0; n < BATCHSIZE; n++) {
+            obj = PyIter_Next(iter);
+            if (obj == NULL) {
+                if (PyErr_Occurred())
+                    goto error;
+                break;
+            }
+            slice[n] = obj;
+        }
+
+        if (n > 1) {
+            /* Pump out MARK, slice[0:n], APPENDS. */
+            if (pickler_write(self, &mark_op, 1) < 0)
+                goto error;
+            for (i = 0; i < n; i++) {
+                if (save(self, slice[i], 0) < 0)
+                    goto error;
+            }
+            if (pickler_write(self, &appends_op, 1) < 0)
+                goto error;
+        }
+        else if (n == 1) {
+            if (save(self, slice[0], 0) < 0 || 
+                pickler_write(self, &append_op, 1) < 0)
+                goto error;
+        }
+
+        for (i = 0; i < n; i++) {
+            Py_DECREF(slice[i]);
+        }
+    } while (n == BATCHSIZE);
+    return 0;
+
+  error:
+    while (--n >= 0) {
+        Py_DECREF(slice[n]);
+    }
+    return -1;
+}
+
+static int
+save_list(PicklerObject *self, PyObject *obj)
+{
+    PyObject *iter;
+    char header[3];
+    int len;
+    int status = 0;
+
+    if (self->fast && !fast_save_enter(self, obj))
+        goto error;
+
+    /* Create an empty list. */
+    if (self->bin) {
+        header[0] = EMPTY_LIST;
+        len = 1;
+    }
+    else {
+        header[0] = MARK;
+        header[1] = LIST;
+        len = 2;
+    }
+
+    if (pickler_write(self, header, len) < 0)
+        goto error;
+
+    /* Get list length, and bow out early if empty. */
+    if ((len = PyList_Size(obj)) < 0)
+        goto error;
+
+    if (memo_put(self, obj) < 0)
+        goto error;
+
+    if (len != 0) {
+        /* Save the list elements. */
+        iter = PyObject_GetIter(obj);
+        if (iter == NULL)
+            goto error;
+        status = batch_list(self, iter);
+        Py_DECREF(iter);
+    }
+
+    if (0) {
+  error:
+        status = -1;
+    }
+
+    if (self->fast && !fast_save_leave(self, obj))
+        status = -1;
+
+    return status;
+}
+
+/* iter is an iterator giving (key, value) pairs, and we batch up chunks of
+ *     MARK key value ... key value SETITEMS
+ * opcode sequences.  Calling code should have arranged to first create an
+ * empty dict, or dict-like object, for the SETITEMS to operate on.
+ * Returns 0 on success, <0 on error.
+ *
+ * This is very much like batch_list().  The difference between saving
+ * elements directly, and picking apart two-tuples, is so long-winded at
+ * the C level, though, that attempts to combine these routines were too
+ * ugly to bear.
+ */
+static int
+batch_dict(PicklerObject *self, PyObject *iter)
+{
+    PyObject *obj;
+    PyObject *slice[BATCHSIZE];
+    int i, n;
+
+    const char mark_op = MARK;
+    const char setitem_op = SETITEM;
+    const char setitems_op = SETITEMS;
+
+    assert(iter != NULL);
+
+    if (self->proto == 0) {
+        /* SETITEMS isn't available; do one at a time. */
+        for (;;) {
+            obj = PyIter_Next(iter);
+            if (obj == NULL) {
+                if (PyErr_Occurred())
+                    return -1;
+                break;
+            }
+            if (!PyTuple_Check(obj) || PyTuple_Size(obj) != 2) {
+                PyErr_SetString(PyExc_TypeError, "dict items "
+                                "iterator must return 2-tuples");
+                return -1;
+            }
+            i = save(self, PyTuple_GET_ITEM(obj, 0), 0);
+            if (i >= 0)
+                i = save(self, PyTuple_GET_ITEM(obj, 1), 0);
+            Py_DECREF(obj);
+            if (i < 0)
+                return -1;
+            if (pickler_write(self, &setitem_op, 1) < 0)
+                return -1;
+        }
+        return 0;
+    }
+
+    /* proto > 0:  write in batches of BATCHSIZE. */
+    do {
+        /* Get next group of (no more than) BATCHSIZE elements. */
+        for (n = 0; n < BATCHSIZE; n++) {
+            obj = PyIter_Next(iter);
+            if (obj == NULL) {
+                if (PyErr_Occurred())
+                    goto error;
+                break;
+            }
+            if (!PyTuple_Check(obj) || PyTuple_Size(obj) != 2) {
+                PyErr_SetString(PyExc_TypeError, "dict items "
+                                "iterator must return 2-tuples");
+                goto error;
+            }
+            slice[n] = obj;
+        }
+
+        if (n > 1) {
+            /* Pump out MARK, slice[0:n], SETITEMS. */
+            if (pickler_write(self, &mark_op, 1) < 0)
+                goto error;
+            for (i = 0; i < n; i++) {
+                obj = slice[i];
+                if (save(self, PyTuple_GET_ITEM(obj, 0), 0) < 0 ||
+                    save(self, PyTuple_GET_ITEM(obj, 1), 0) < 0)
+                    goto error;
+            }
+            if (pickler_write(self, &setitems_op, 1) < 0)
+                goto error;
+        }
+        else if (n == 1) {
+            obj = slice[0];
+            if (save(self, PyTuple_GET_ITEM(obj, 0), 0) < 0 ||
+                save(self, PyTuple_GET_ITEM(obj, 1), 0) < 0 ||
+                pickler_write(self, &setitem_op, 1) < 0)
+                goto error;
+        }
+
+        for (i = 0; i < n; i++) {
+            Py_DECREF(slice[i]);
+        }
+    } while (n == BATCHSIZE);
+    return 0;
+
+  error:
+    while (--n >= 0) {
+        Py_DECREF(slice[n]);
+    }
+    return -1;
+}
+
+static int
+save_dict(PicklerObject *self, PyObject *obj)
+{
+    PyObject *items, *iter;
+    char header[3];
+    int len;
+    int status = 0;
+
+    if (self->fast && !fast_save_enter(self, obj))
+        goto error;
+
+    /* Create an empty dict. */
+    if (self->bin) {
+        header[0] = EMPTY_DICT;
+        len = 1;
+    }
+    else {
+        header[0] = MARK;
+        header[1] = DICT;
+        len = 2;
+    }
+
+    if (pickler_write(self, header, len) < 0)
+        goto error;
+
+    /* Get dict size, and bow out early if empty. */
+    if ((len = PyDict_Size(obj)) < 0)
+        goto error;
+
+    if (memo_put(self, obj) < 0)
+        goto error;
+
+    if (len != 0) {
+        /* Save the dict items. */
+        items = PyObject_CallMethod(obj, "items", "()");
+        if (items == NULL)
+            goto error;
+        iter = PyObject_GetIter(items);
+        Py_DECREF(items);
+        if (iter == NULL)
+            goto error;
+        status = batch_dict(self, iter);
+        Py_DECREF(iter);
+    }
+
+    if (0) {
+  error:
+        status = -1;
+    }
+
+    if (self->fast && !fast_save_leave(self, obj))
+        status = -1;
+
+    return status;
+}
+
+static int
+save_global(PicklerObject *self, PyObject *obj, PyObject *name)
+{
+    static PyObject *name_str = NULL;
+    PyObject *global_name = NULL;
+    PyObject *module_name = NULL;
+    PyObject *module = NULL;
+    PyObject *cls;
+    int status = 0;
+
+    const char global_op = GLOBAL;
+
+    if (name_str == NULL) {
+        name_str = PyUnicode_InternFromString("__name__");
+        if (name_str == NULL)
+            goto error;
+    }
+
+    if (name) {
+        global_name = name;
+        Py_INCREF(global_name);
+    }
+    else {
+        global_name = PyObject_GetAttr(obj, name_str);
+        if (global_name == NULL)
+            goto error;
+    }
+
+    module_name = whichmodule(obj, global_name);
+    if (module_name == NULL)
+        goto error;
+
+    /* XXX: Change to use the import C API directly with level=0 to disallow
+       relative imports.
+
+       XXX: PyImport_ImportModuleLevel could be used. However, this bypasses
+       builtins.__import__. Therefore, _pickle, unlike pickle.py, will ignore
+       custom import functions (IMHO, this would be a nice security
+       feature). The import C API would need to be extended to support the
+       extra parameters of __import__ to fix that. */
+    module = PyImport_Import(module_name);
+    if (module == NULL) {
+        PyErr_Format(PicklingError,
+                     "Can't pickle %R: import of module %R failed",
+                     obj, module_name);
+        goto error;
+    }
+    cls = PyObject_GetAttr(module, global_name);
+    if (cls == NULL) {
+        PyErr_Format(PicklingError,
+                     "Can't pickle %R: attribute lookup %S.%S failed",
+                     obj, module_name, global_name);
+        goto error;
+    }
+    if (cls != obj) {
+        Py_DECREF(cls);
+        PyErr_Format(PicklingError,
+                     "Can't pickle %R: it's not the same object as %S.%S",
+                     obj, module_name, global_name);
+        goto error;
+    }
+    Py_DECREF(cls);
+
+    if (self->proto >= 2) {
+        /* See whether this is in the extension registry, and if
+         * so generate an EXT opcode.
+         */
+        PyObject *code_obj;      /* extension code as Python object */
+        long code;               /* extension code as C value */
+        char pdata[5];
+        int n;
+
+        PyTuple_SET_ITEM(two_tuple, 0, module_name);
+        PyTuple_SET_ITEM(two_tuple, 1, global_name);
+        code_obj = PyDict_GetItem(extension_registry, two_tuple);
+        /* The object is not registered in the extension registry.
+           This is the most likely code path. */
+        if (code_obj == NULL)
+            goto gen_global;
+
+        /* XXX: pickle.py doesn't check neither the type, nor the range
+           of the value returned by the extension_registry. It should for
+           consistency. */
+
+        /* Verify code_obj has the right type and value. */
+        if (!PyLong_Check(code_obj)) {
+            PyErr_Format(PicklingError,
+                         "Can't pickle %R: extension code %R isn't an integer",
+                         obj, code_obj);
+            goto error;
+        }
+        code = PyLong_AS_LONG(code_obj);
+        if (code <= 0 || code > 0x7fffffffL) {
+            PyErr_Format(PicklingError,
+                         "Can't pickle %R: extension code %ld is out of range",
+                         obj, code);
+            goto error;
+        }
+
+        /* Generate an EXT opcode. */
+        if (code <= 0xff) {
+            pdata[0] = EXT1;
+            pdata[1] = (unsigned char)code;
+            n = 2;
+        }
+        else if (code <= 0xffff) {
+            pdata[0] = EXT2;
+            pdata[1] = (unsigned char)(code & 0xff);
+            pdata[2] = (unsigned char)((code >> 8) & 0xff);
+            n = 3;
+        }
+        else {
+            pdata[0] = EXT4;
+            pdata[1] = (unsigned char)(code & 0xff);
+            pdata[2] = (unsigned char)((code >> 8) & 0xff);
+            pdata[3] = (unsigned char)((code >> 16) & 0xff);
+            pdata[4] = (unsigned char)((code >> 24) & 0xff);
+            n = 5;
+        }
+
+        if (pickler_write(self, pdata, n) < 0)
+            goto error;
+    }
+    else {
+        /* Generate a normal global opcode if we are using a pickle
+           protocol <= 2, or if the object is not registered in the
+           extension registry. */
+        PyObject *encoded;
+        PyObject *(*unicode_encoder)(PyObject *);
+
+  gen_global:
+        if (pickler_write(self, &global_op, 1) < 0)
+            goto error;
+
+        /* Since Python 3.0 now supports non-ASCII identifiers, we encode both
+           the module name and the global name using UTF-8. We do so only when
+           we are using the pickle protocol newer than version 3. This is to
+           ensure compatibility with older Unpickler running on Python 2.x. */
+        if (self->proto >= 3) {
+            unicode_encoder = PyUnicode_AsUTF8String;
+        }
+        else {
+            unicode_encoder = PyUnicode_AsASCIIString;
+        }
+
+        /* Save the name of the module. */
+        encoded = unicode_encoder(module_name);
+        if (encoded == NULL) {
+            if (PyErr_ExceptionMatches(PyExc_UnicodeEncodeError))
+                PyErr_Format(PicklingError,
+                             "can't pickle module identifier '%S' using "
+                             "pickle protocol %i", module_name, self->proto);
+            goto error;
+        }
+        if (pickler_write(self, PyBytes_AS_STRING(encoded),
+                          PyBytes_GET_SIZE(encoded)) < 0) {
+            Py_DECREF(encoded);
+            goto error;
+        }
+        Py_DECREF(encoded);
+        if(pickler_write(self, "\n", 1) < 0)
+            goto error;
+
+        /* Save the name of the module. */
+        encoded = unicode_encoder(global_name);
+        if (encoded == NULL) {
+            if (PyErr_ExceptionMatches(PyExc_UnicodeEncodeError))
+                PyErr_Format(PicklingError,
+                             "can't pickle global identifier '%S' using "
+                             "pickle protocol %i", global_name, self->proto);
+            goto error;
+        }
+        if (pickler_write(self, PyBytes_AS_STRING(encoded),
+                          PyBytes_GET_SIZE(encoded)) < 0) {
+            Py_DECREF(encoded);
+            goto error;
+        }
+        Py_DECREF(encoded);
+        if(pickler_write(self, "\n", 1) < 0)
+            goto error;
+
+        /* Memoize the object. */
+        if (memo_put(self, obj) < 0)
+            goto error;
+    }
+
+    if (0) {
+  error:
+        status = -1;
+    }
+    Py_XDECREF(module_name);
+    Py_XDECREF(global_name);
+    Py_XDECREF(module);
+
+    return status;
+}
+
+static int
+save_pers(PicklerObject *self, PyObject *obj, PyObject *func)
+{
+    PyObject *pid = NULL;
+    int status = 0;
+
+    const char persid_op = PERSID;
+    const char binpersid_op = BINPERSID;
+
+    Py_INCREF(obj);
+    pid = pickler_call(self, func, obj);
+    if (pid == NULL)
+        return -1;
+
+    if (pid != Py_None) {
+        if (self->bin) {
+            if (save(self, pid, 1) < 0 ||
+                pickler_write(self, &binpersid_op, 1) < 0)
+                goto error;
+        }
+        else {
+            PyObject *pid_str = NULL;
+            char *pid_ascii_bytes;
+            Py_ssize_t size;
+
+            pid_str = PyObject_Str(pid);
+            if (pid_str == NULL)
+                goto error;
+
+            /* XXX: Should it check whether the persistent id only contains
+               ASCII characters? And what if the pid contains embedded
+               newlines? */
+            pid_ascii_bytes = PyUnicode_AsStringAndSize(pid_str, &size);
+            Py_DECREF(pid_str);
+            if (pid_ascii_bytes == NULL)
+                goto error;
+
+            if (pickler_write(self, &persid_op, 1) < 0 ||
+                pickler_write(self, pid_ascii_bytes, size) < 0 ||
+                pickler_write(self, "\n", 1) < 0)
+                goto error;
+        }
+        status = 1;
+    }
+
+    if (0) {
+  error:
+        status = -1;
+    }
+    Py_XDECREF(pid);
+
+    return status;
+}
+
+/* We're saving obj, and args is the 2-thru-5 tuple returned by the
+ * appropriate __reduce__ method for obj.
+ */
+static int
+save_reduce(PicklerObject *self, PyObject *args, PyObject *obj)
+{
+    PyObject *callable;
+    PyObject *argtup;
+    PyObject *state = NULL;
+    PyObject *listitems = NULL;
+    PyObject *dictitems = NULL;
+
+    int use_newobj = self->proto >= 2;
+
+    const char reduce_op = REDUCE;
+    const char build_op = BUILD;
+    const char newobj_op = NEWOBJ;
+
+    if (!PyArg_UnpackTuple(args, "save_reduce", 2, 5,
+                           &callable, &argtup, &state, &listitems, &dictitems))
+        return -1;
+
+    if (!PyCallable_Check(callable)) {
+        PyErr_SetString(PicklingError,
+                        "first argument of save_reduce() must be callable");
+        return -1;
+    }
+    if (!PyTuple_Check(argtup)) {
+        PyErr_SetString(PicklingError,
+                        "second argument of save_reduce() must be a tuple");
+        return -1;
+    }
+
+    if (state == Py_None)
+        state = NULL;
+    if (listitems == Py_None)
+        listitems = NULL;
+    if (dictitems == Py_None)
+        dictitems = NULL;
+
+    /* Protocol 2 special case: if callable's name is __newobj__, use
+       NEWOBJ. */
+    if (use_newobj) {
+        static PyObject *newobj_str = NULL;
+        PyObject *name_str;
+
+        if (newobj_str == NULL) {
+            newobj_str = PyUnicode_InternFromString("__newobj__");
+        }
+
+        name_str = PyObject_GetAttrString(callable, "__name__");
+        if (name_str == NULL) {
+            if (PyErr_ExceptionMatches(PyExc_AttributeError))
+                PyErr_Clear();
+            else
+                return -1;
+            use_newobj = 0;
+        }
+        else {
+            use_newobj = PyUnicode_Check(name_str) && 
+                PyUnicode_Compare(name_str, newobj_str) == 0;
+            Py_DECREF(name_str);
+        }
+    }
+    if (use_newobj) {
+        PyObject *cls;
+        PyObject *newargtup;
+        PyObject *obj_class;
+        int p;
+
+        /* Sanity checks. */
+        if (Py_SIZE(argtup) < 1) {
+            PyErr_SetString(PicklingError, "__newobj__ arglist is empty");
+            return -1;
+        }
+
+        cls = PyTuple_GET_ITEM(argtup, 0);
+        if (!PyObject_HasAttrString(cls, "__new__")) {
+            PyErr_SetString(PicklingError, "args[0] from "
+                            "__newobj__ args has no __new__");
+            return -1;
+        }
+
+        if (obj != NULL) {
+            obj_class = PyObject_GetAttrString(obj, "__class__");
+            if (obj_class == NULL) {
+                if (PyErr_ExceptionMatches(PyExc_AttributeError))
+                    PyErr_Clear();
+                else
+                    return -1;
+            }
+            p = obj_class != cls;    /* true iff a problem */
+            Py_DECREF(obj_class);
+            if (p) {
+                PyErr_SetString(PicklingError, "args[0] from "
+                                "__newobj__ args has the wrong class");
+                return -1;
+            }
+        }
+        /* XXX: These calls save() are prone to infinite recursion. Imagine
+           what happen if the value returned by the __reduce__() method of
+           some extension type contains another object of the same type. Ouch!
+
+           Here is a quick example, that I ran into, to illustrate what I
+           mean:
+
+             >>> import pickle, copyreg
+             >>> copyreg.dispatch_table.pop(complex)
+             >>> pickle.dumps(1+2j)
+             Traceback (most recent call last):
+               ...
+             RuntimeError: maximum recursion depth exceeded
+
+           Removing the complex class from copyreg.dispatch_table made the
+           __reduce_ex__() method emit another complex object:
+
+             >>> (1+1j).__reduce_ex__(2)
+             (<function __newobj__ at 0xb7b71c3c>,
+               (<class 'complex'>, (1+1j)), None, None, None)
+
+           Thus when save() was called on newargstup (the 2nd item) recursion
+           ensued. Of course, the bug was in the complex class which had a
+           broken __getnewargs__() that emitted another complex object. But,
+           the point, here, is it is quite easy to end up with a broken reduce
+           function. */
+
+        /* Save the class and its __new__ arguments. */
+        if (save(self, cls, 0) < 0)
+            return -1;
+
+        newargtup = PyTuple_GetSlice(argtup, 1, Py_SIZE(argtup));
+        if (newargtup == NULL)
+            return -1;
+
+        p = save(self, newargtup, 0);
+        Py_DECREF(newargtup);
+        if (p < 0)
+            return -1;
+
+        /* Add NEWOBJ opcode. */
+        if (pickler_write(self, &newobj_op, 1) < 0)
+            return -1;
+    }
+    else { /* Not using NEWOBJ. */
+        if (save(self, callable, 0) < 0 ||
+            save(self, argtup, 0) < 0 ||
+            pickler_write(self, &reduce_op, 1) < 0)
+            return -1;
+    }
+
+    /* obj can be NULL when save_reduce() is used directly. A NULL obj means
+       the caller do not want to memoize the object. Not particularly useful,
+       but that is to mimic the behavior save_reduce() in pickle.py when
+       obj is None. */
+    if (obj && memo_put(self, obj) < 0)
+        return -1;
+
+    if (listitems && batch_list(self, listitems) < 0)
+        return -1;
+
+    if (dictitems && batch_dict(self, dictitems) < 0)
+        return -1;
+
+    if (state) {
+        if (save(self, state, 0) < 0 || 
+            pickler_write(self, &build_op, 1) < 0)
+            return -1;
+    }
+
+    return 0;
+}
+
+static int
+save(PicklerObject *self, PyObject *obj, int pers_save)
+{
+    PyTypeObject *type;
+    PyObject *reduce_func = NULL;
+    PyObject *reduce_value = NULL;
+    PyObject *memo_key = NULL;
+    int status = 0;
+
+    /* XXX: Use Py_EnterRecursiveCall()? */
+    if (++self->nesting > Py_GetRecursionLimit()) {
+        PyErr_SetString(PyExc_RuntimeError,
+                        "maximum recursion depth exceeded");
+        goto error;
+    }
+
+    /* The extra pers_save argument is necessary to avoid calling save_pers()
+       on its returned object. */
+    if (!pers_save && self->pers_func) {
+        /* save_pers() returns:
+            -1   to signal an error;
+             0   if it did nothing successfully;
+             1   if a persistent id was saved.
+         */
+        if ((status = save_pers(self, obj, self->pers_func)) != 0)
+            goto done;
+    }
+
+    type = Py_TYPE(obj);
+
+    /* XXX: The old cPickle had an optimization that used switch-case
+       statement dispatching on the first letter of the type name. It was
+       probably not a bad idea after all. If benchmarks shows that particular
+       optimization had some real benefits, it would be nice to add it
+       back. */
+
+    /* Atom types; these aren't memoized, so don't check the memo. */
+
+    if (obj == Py_None) {
+        status = save_none(self, obj);
+        goto done;
+    }
+    else if (obj == Py_False || obj == Py_True) {
+        status = save_bool(self, obj);
+        goto done;
+    }
+    else if (type == &PyLong_Type) {
+        status = save_long(self, obj);
+        goto done;
+    }
+    else if (type == &PyFloat_Type) {
+        status = save_float(self, obj);
+        goto done;
+    }
+
+    /* Check the memo to see if it has the object. If so, generate
+       a GET (or BINGET) opcode, instead of pickling the object
+       once again. */
+    memo_key = PyLong_FromVoidPtr(obj);
+    if (memo_key == NULL)
+        goto error;
+    if (PyDict_GetItem(self->memo, memo_key)) {
+        if (memo_get(self, memo_key) < 0)
+            goto error;
+        goto done;
+    }
+
+    if (type == &PyBytes_Type) {
+        status = save_bytes(self, obj);
+        goto done;
+    }
+    else if (type == &PyUnicode_Type) {
+        status = save_unicode(self, obj);
+        goto done;
+    }
+    else if (type == &PyDict_Type) {
+        status = save_dict(self, obj);
+        goto done;
+    }
+    else if (type == &PyList_Type) {
+        status = save_list(self, obj);
+        goto done;
+    }
+    else if (type == &PyTuple_Type) {
+        status = save_tuple(self, obj);
+        goto done;
+    }
+    else if (type == &PyType_Type) {
+        status = save_global(self, obj, NULL);
+        goto done;
+    }
+    else if (type == &PyFunction_Type) {
+        status = save_global(self, obj, NULL);
+        if (status < 0 && PyErr_ExceptionMatches(PickleError)) {
+            /* fall back to reduce */
+            PyErr_Clear();
+        }
+        else {
+            goto done;
+        }
+    }
+    else if (type == &PyCFunction_Type) {
+        status = save_global(self, obj, NULL);
+        goto done;
+    }
+    else if (PyType_IsSubtype(type, &PyType_Type)) {
+        status = save_global(self, obj, NULL);
+        goto done;
+    }
+
+    /* XXX: This part needs some unit tests. */
+
+    /* Get a reduction callable, and call it.  This may come from
+     * copyreg.dispatch_table, the object's __reduce_ex__ method,
+     * or the object's __reduce__ method.
+     */
+    reduce_func = PyDict_GetItem(dispatch_table, (PyObject *)type);
+    if (reduce_func != NULL) {
+        /* Here, the reference count of the reduce_func object returned by
+           PyDict_GetItem needs to be increased to be consistent with the one
+           returned by PyObject_GetAttr. This is allow us to blindly DECREF
+           reduce_func at the end of the save() routine.
+        */
+        Py_INCREF(reduce_func);
+        Py_INCREF(obj);
+        reduce_value = pickler_call(self, reduce_func, obj);
+    }
+    else {
+        static PyObject *reduce_str = NULL;
+        static PyObject *reduce_ex_str = NULL;
+
+        /* Cache the name of the reduce methods. */
+        if (reduce_str == NULL) {
+            reduce_str = PyUnicode_InternFromString("__reduce__");
+            if (reduce_str == NULL)
+                goto error;
+            reduce_ex_str = PyUnicode_InternFromString("__reduce_ex__");
+            if (reduce_ex_str == NULL)
+                goto error;
+        }
+
+        /* XXX: If the __reduce__ method is defined, __reduce_ex__ is
+           automatically defined as __reduce__. While this is convenient, this
+           make it impossible to know which method was actually called. Of
+           course, this is not a big deal. But still, it would be nice to let
+           the user know which method was called when something go
+           wrong. Incidentally, this means if __reduce_ex__ is not defined, we
+           don't actually have to check for a __reduce__ method. */
+
+        /* Check for a __reduce_ex__ method. */
+        reduce_func = PyObject_GetAttr(obj, reduce_ex_str);
+        if (reduce_func != NULL) {
+            PyObject *proto;
+            proto = PyLong_FromLong(self->proto);
+            if (proto != NULL) {
+                reduce_value = pickler_call(self, reduce_func, proto);
+            }
+        }
+        else {
+            if (PyErr_ExceptionMatches(PyExc_AttributeError))
+                PyErr_Clear();
+            else
+                goto error;
+            /* Check for a __reduce__ method. */
+            reduce_func = PyObject_GetAttr(obj, reduce_str);
+            if (reduce_func != NULL) {
+                reduce_value = PyObject_Call(reduce_func, empty_tuple, NULL);
+            }
+            else {
+                PyErr_Format(PicklingError, "can't pickle '%.200s' object: %R",
+                             type->tp_name, obj);
+                goto error;
+            }
+        }
+    }
+
+    if (reduce_value == NULL)
+        goto error;
+
+    if (PyUnicode_Check(reduce_value)) {
+        status = save_global(self, obj, reduce_value);
+        goto done;
+    }
+
+    if (!PyTuple_Check(reduce_value)) {
+        PyErr_SetString(PicklingError,
+                        "__reduce__ must return a string or tuple");
+        goto error;
+    }
+    if (Py_SIZE(reduce_value) < 2 || Py_SIZE(reduce_value) > 5) {
+        PyErr_SetString(PicklingError, "tuple returned by __reduce__ "
+                        "must contain 2 through 5 elements");
+        goto error;
+    }
+    if (!PyTuple_Check(PyTuple_GET_ITEM(reduce_value, 1))) {
+        PyErr_SetString(PicklingError, "second item of the tuple "
+                        "returned by __reduce__ must be a tuple");
+        goto error;
+    }
+
+    status = save_reduce(self, reduce_value, obj);
+
+    if (0) {
+  error:
+        status = -1;
+    }
+  done:
+    self->nesting--;
+    Py_XDECREF(memo_key);
+    Py_XDECREF(reduce_func);
+    Py_XDECREF(reduce_value);
+
+    return status;
+}
+
+static int
+dump(PicklerObject *self, PyObject *obj)
+{
+    const char stop_op = STOP;
+
+    if (self->proto >= 2) {
+        char header[2];
+
+        header[0] = PROTO;
+        assert(self->proto >= 0 && self->proto < 256);
+        header[1] = (unsigned char)self->proto;
+        if (pickler_write(self, header, 2) < 0)
+            return -1;
+    }
+
+    if (save(self, obj, 0) < 0 ||
+        pickler_write(self, &stop_op, 1) < 0 ||
+        pickler_write(self, NULL, 0) < 0)
+        return -1;
+
+    return 0;
+}
+
+PyDoc_STRVAR(Pickler_clear_memo_doc,
+"clear_memo() -> None. Clears the pickler's \"memo\"."
+"\n"
+"The memo is the data structure that remembers which objects the\n"
+"pickler has already seen, so that shared or recursive objects are\n"
+"pickled by reference and not by value.  This method is useful when\n"
+"re-using picklers.");
+
+static PyObject *
+Pickler_clear_memo(PicklerObject *self)
+{
+    if (self->memo)
+        PyDict_Clear(self->memo);
+
+    Py_RETURN_NONE;
+}
+
+PyDoc_STRVAR(Pickler_dump_doc,
+"dump(obj) -> None. Write a pickled representation of obj to the open file.");
+
+static PyObject *
+Pickler_dump(PicklerObject *self, PyObject *args)
+{
+    PyObject *obj;
+
+    if (!PyArg_ParseTuple(args, "O:dump", &obj))
+        return NULL;
+
+    if (dump(self, obj) < 0)
+        return NULL;
+
+    Py_RETURN_NONE;
+}
+
+static struct PyMethodDef Pickler_methods[] = {
+    {"dump", (PyCFunction)Pickler_dump, METH_VARARGS,
+     Pickler_dump_doc},
+    {"clear_memo", (PyCFunction)Pickler_clear_memo, METH_NOARGS,
+     Pickler_clear_memo_doc},
+    {NULL, NULL}                /* sentinel */
+};
+
+static void
+Pickler_dealloc(PicklerObject *self)
+{
+    PyObject_GC_UnTrack(self);
+
+    Py_XDECREF(self->write);
+    Py_XDECREF(self->memo);
+    Py_XDECREF(self->pers_func);
+    Py_XDECREF(self->arg);
+    Py_XDECREF(self->fast_memo);
+
+    PyMem_Free(self->write_buf);
+
+    Py_TYPE(self)->tp_free((PyObject *)self);
+}
+
+static int
+Pickler_traverse(PicklerObject *self, visitproc visit, void *arg)
+{
+    Py_VISIT(self->write);
+    Py_VISIT(self->memo);
+    Py_VISIT(self->pers_func);
+    Py_VISIT(self->arg);
+    Py_VISIT(self->fast_memo);
+    return 0;
+}
+
+static int
+Pickler_clear(PicklerObject *self)
+{
+    Py_CLEAR(self->write);
+    Py_CLEAR(self->memo);
+    Py_CLEAR(self->pers_func);
+    Py_CLEAR(self->arg);
+    Py_CLEAR(self->fast_memo);
+
+    PyMem_Free(self->write_buf);
+    self->write_buf = NULL;
+
+    return 0;
+}
+
+PyDoc_STRVAR(Pickler_doc,
+"Pickler(file, protocol=None)"
+"\n"
+"This takes a binary file for writing a pickle data stream.\n"
+"\n"
+"The optional protocol argument tells the pickler to use the\n"
+"given protocol; supported protocols are 0, 1, 2, 3.  The default\n"
+"protocol is 3; a backward-incompatible protocol designed for\n"
+"Python 3.0.\n"
+"\n"
+"Specifying a negative protocol version selects the highest\n"
+"protocol version supported.  The higher the protocol used, the\n"
+"more recent the version of Python needed to read the pickle\n"
+"produced.\n"
+"\n"
+"The file argument must have a write() method that accepts a single\n"
+"bytes argument. It can thus be a file object opened for binary\n"
+"writing, a io.BytesIO instance, or any other custom object that\n"
+"meets this interface.\n");
+
+static int
+Pickler_init(PicklerObject *self, PyObject *args, PyObject *kwds)
+{
+    static char *kwlist[] = {"file", "protocol", 0};
+    PyObject *file;
+    PyObject *proto_obj = NULL;
+    long proto = 0;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|O:Pickler",
+                                     kwlist, &file, &proto_obj))
+        return -1;
+
+    /* In case of multiple __init__() calls, clear previous content. */
+    if (self->write != NULL)
+        (void)Pickler_clear(self);
+
+    if (proto_obj == NULL || proto_obj == Py_None)
+        proto = DEFAULT_PROTOCOL;
+    else
+        proto = PyLong_AsLong(proto_obj);
+
+    if (proto < 0)
+        proto = HIGHEST_PROTOCOL;
+    if (proto > HIGHEST_PROTOCOL) {
+        PyErr_Format(PyExc_ValueError, "pickle protocol must be <= %d",
+                     HIGHEST_PROTOCOL);
+        return -1;
+    }
+
+	self->proto = proto;
+	self->bin = proto > 0;
+	self->arg = NULL;
+    self->nesting = 0;
+	self->fast = 0;
+	self->fast_nesting = 0;
+	self->fast_memo = NULL;
+
+    if (!PyObject_HasAttrString(file, "write")) {
+        PyErr_SetString(PyExc_TypeError,
+                        "file must have a 'write' attribute");
+        return -1;
+    }
+    self->write = PyObject_GetAttrString(file, "write");
+    if (self->write == NULL)
+        return -1;
+	self->buf_size = 0;
+    self->write_buf = (char *)PyMem_Malloc(WRITE_BUF_SIZE);
+    if (self->write_buf == NULL) {
+        PyErr_NoMemory();
+        return -1;
+    }
+    self->pers_func = NULL;
+    if (PyObject_HasAttrString((PyObject *)self, "persistent_id")) {
+        self->pers_func = PyObject_GetAttrString((PyObject *)self,
+                                                 "persistent_id");
+        if (self->pers_func == NULL)
+            return -1;
+    }
+    self->memo = PyDict_New();
+    if (self->memo == NULL)
+        return -1;
+
+    return 0;
+}
+
+static PyObject *
+Pickler_get_memo(PicklerObject *self)
+{
+    if (self->memo == NULL)
+        PyErr_SetString(PyExc_AttributeError, "memo");
+    else
+        Py_INCREF(self->memo);
+    return self->memo;
+}
+
+static int
+Pickler_set_memo(PicklerObject *self, PyObject *value)
+{
+    PyObject *tmp;
+
+    if (value == NULL) {
+        PyErr_SetString(PyExc_TypeError,
+                        "attribute deletion is not supported");
+        return -1;
+    }
+    if (!PyDict_Check(value)) {
+        PyErr_SetString(PyExc_TypeError, "memo must be a dictionary");
+        return -1;
+    }
+
+    tmp = self->memo;
+    Py_INCREF(value);
+    self->memo = value;
+    Py_XDECREF(tmp);
+
+    return 0;
+}
+
+static PyObject *
+Pickler_get_persid(PicklerObject *self)
+{
+    if (self->pers_func == NULL)
+        PyErr_SetString(PyExc_AttributeError, "persistent_id");
+    else
+        Py_INCREF(self->pers_func);
+    return self->pers_func;
+}
+
+static int
+Pickler_set_persid(PicklerObject *self, PyObject *value)
+{
+    PyObject *tmp;
+
+    if (value == NULL) {
+        PyErr_SetString(PyExc_TypeError,
+                        "attribute deletion is not supported");
+        return -1;
+    }
+    if (!PyCallable_Check(value)) {
+        PyErr_SetString(PyExc_TypeError,
+                        "persistent_id must be a callable taking one argument");
+        return -1;
+    }
+
+    tmp = self->pers_func;
+    Py_INCREF(value);
+    self->pers_func = value;
+    Py_XDECREF(tmp);      /* self->pers_func can be NULL, so be careful. */
+
+    return 0;
+}
+
+static PyMemberDef Pickler_members[] = {
+    {"bin", T_INT, offsetof(PicklerObject, bin)},
+    {"fast", T_INT, offsetof(PicklerObject, fast)},
+    {NULL}
+};
+
+static PyGetSetDef Pickler_getsets[] = {
+    {"memo",          (getter)Pickler_get_memo,
+                      (setter)Pickler_set_memo},
+    {"persistent_id", (getter)Pickler_get_persid,
+                      (setter)Pickler_set_persid},
+    {NULL}
+};
+
+static PyTypeObject Pickler_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "_pickle.Pickler"  ,                /*tp_name*/
+    sizeof(PicklerObject),              /*tp_basicsize*/
+    0,                                  /*tp_itemsize*/
+    (destructor)Pickler_dealloc,        /*tp_dealloc*/
+    0,                                  /*tp_print*/
+    0,                                  /*tp_getattr*/
+    0,                                  /*tp_setattr*/
+    0,                                  /*tp_compare*/
+    0,                                  /*tp_repr*/
+    0,                                  /*tp_as_number*/
+    0,                                  /*tp_as_sequence*/
+    0,                                  /*tp_as_mapping*/
+    0,                                  /*tp_hash*/
+    0,                                  /*tp_call*/
+    0,                                  /*tp_str*/
+    0,                                  /*tp_getattro*/
+    0,                                  /*tp_setattro*/
+    0,                                  /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,
+    Pickler_doc,                        /*tp_doc*/
+    (traverseproc)Pickler_traverse,     /*tp_traverse*/
+    (inquiry)Pickler_clear,             /*tp_clear*/
+    0,                                  /*tp_richcompare*/
+    0,                                  /*tp_weaklistoffset*/
+    0,                                  /*tp_iter*/
+    0,                                  /*tp_iternext*/
+    Pickler_methods,                    /*tp_methods*/
+    Pickler_members,                    /*tp_members*/
+    Pickler_getsets,                    /*tp_getset*/
+    0,                                  /*tp_base*/
+    0,                                  /*tp_dict*/
+    0,                                  /*tp_descr_get*/
+    0,                                  /*tp_descr_set*/
+    0,                                  /*tp_dictoffset*/
+    (initproc)Pickler_init,             /*tp_init*/
+    PyType_GenericAlloc,                /*tp_alloc*/
+    PyType_GenericNew,                  /*tp_new*/
+    PyObject_GC_Del,                    /*tp_free*/
+    0,                                  /*tp_is_gc*/
+};
+
+/* Temporary helper for calling self.find_class(). 
+
+   XXX: It would be nice to able to avoid Python function call overhead, by
+   using directly the C version of find_class(), when find_class() is not
+   overridden by a subclass. Although, this could become rather hackish. A
+   simpler optimization would be to call the C function when self is not a
+   subclass instance. */
+static PyObject *
+find_class(UnpicklerObject *self, PyObject *module_name, PyObject *global_name)
+{
+    return PyObject_CallMethod((PyObject *)self, "find_class", "OO",
+                               module_name, global_name);
+}
+
+static int
+marker(UnpicklerObject *self)
+{
+    if (self->num_marks < 1) {
+        PyErr_SetString(UnpicklingError, "could not find MARK");
+        return -1;
+    }
+
+    return self->marks[--self->num_marks];
+}
+
+static int
+load_none(UnpicklerObject *self)
+{
+    PDATA_APPEND(self->stack, Py_None, -1);
+    return 0;
+}
+
+static int
+bad_readline(void)
+{
+    PyErr_SetString(UnpicklingError, "pickle data was truncated");
+    return -1;
+}
+
+static int
+load_int(UnpicklerObject *self)
+{
+    PyObject *value;
+    char *endptr, *s;
+    Py_ssize_t len;
+    long x;
+
+    if ((len = unpickler_readline(self, &s)) < 0)
+        return -1;
+    if (len < 2)
+        return bad_readline();
+
+    errno = 0;
+    /* XXX: Should the base argument of strtol() be explicitly set to 10? */
+    x = strtol(s, &endptr, 0);
+
+    if (errno || (*endptr != '\n') || (endptr[1] != '\0')) {
+        /* Hm, maybe we've got something long.  Let's try reading
+         * it as a Python long object. */
+        errno = 0;
+        /* XXX: Same thing about the base here. */
+        value = PyLong_FromString(s, NULL, 0); 
+        if (value == NULL) {
+            PyErr_SetString(PyExc_ValueError,
+                            "could not convert string to int");
+            return -1;
+        }
+    }
+    else {
+        if (len == 3 && (x == 0 || x == 1)) {
+            if ((value = PyBool_FromLong(x)) == NULL)
+                return -1;
+        }
+        else {
+            if ((value = PyLong_FromLong(x)) == NULL)
+                return -1;
+        }
+    }
+
+    PDATA_PUSH(self->stack, value, -1);
+    return 0;
+}
+
+static int
+load_bool(UnpicklerObject *self, PyObject *boolean)
+{
+    assert(boolean == Py_True || boolean == Py_False);
+    PDATA_APPEND(self->stack, boolean, -1);
+    return 0;
+}
+
+/* s contains x bytes of a little-endian integer.  Return its value as a
+ * C int.  Obscure:  when x is 1 or 2, this is an unsigned little-endian
+ * int, but when x is 4 it's a signed one.  This is an historical source
+ * of x-platform bugs.
+ */
+static long
+calc_binint(char *s, int size)
+{
+    unsigned char c;
+    int i;
+    long x = 0L;
+
+    for (i = 0; i < size; i++) {
+        c = (unsigned char)s[i];
+        x |= (long)c << (i * 8);
+    }
+#if SIZEOF_LONG > 4
+    /* Unlike BININT1 and BININT2, BININT (more accurately BININT4)
+     * is signed, so on a box with longs bigger than 4 bytes we need
+     * to extend a BININT's sign bit to the full width.
+     */
+    if (x == 4 && x & (1L << 31))
+        x |= (~0L) << 32;
+#endif
+    return x;
+}
+
+static int
+load_binintx(UnpicklerObject *self, char *s, int size)
+{
+    PyObject *value;
+    long x;
+
+    x = calc_binint(s, size);
+
+    if ((value = PyLong_FromLong(x)) == NULL)
+        return -1;
+
+    PDATA_PUSH(self->stack, value, -1);
+    return 0;
+}
+
+static int
+load_binint(UnpicklerObject *self)
+{
+    char *s;
+
+    if (unpickler_read(self, &s, 4) < 0)
+        return -1;
+
+    return load_binintx(self, s, 4);
+}
+
+static int
+load_binint1(UnpicklerObject *self)
+{
+    char *s;
+
+    if (unpickler_read(self, &s, 1) < 0)
+        return -1;
+
+    return load_binintx(self, s, 1);
+}
+
+static int
+load_binint2(UnpicklerObject *self)
+{
+    char *s;
+
+    if (unpickler_read(self, &s, 2) < 0)
+        return -1;
+
+    return load_binintx(self, s, 2);
+}
+
+static int
+load_long(UnpicklerObject *self)
+{
+    PyObject *value;
+    char *s;
+    Py_ssize_t len;
+
+    if ((len = unpickler_readline(self, &s)) < 0)
+        return -1;
+    if (len < 2)
+        return bad_readline();
+
+    /* XXX: Should the base argument explicitly set to 10? */
+    if ((value = PyLong_FromString(s, NULL, 0)) == NULL)
+        return -1;
+
+    PDATA_PUSH(self->stack, value, -1);
+    return 0;
+}
+
+/* 'size' bytes contain the # of bytes of little-endian 256's-complement
+ * data following.
+ */
+static int
+load_counted_long(UnpicklerObject *self, int size)
+{
+    PyObject *value;
+    char *nbytes;
+    char *pdata;
+
+    assert(size == 1 || size == 4);
+    if (unpickler_read(self, &nbytes, size) < 0)
+        return -1;
+
+    size = calc_binint(nbytes, size);
+    if (size < 0) {
+        /* Corrupt or hostile pickle -- we never write one like this */
+        PyErr_SetString(UnpicklingError,
+                        "LONG pickle has negative byte count");
+        return -1;
+    }
+
+    if (size == 0)
+        value = PyLong_FromLong(0L);
+    else {
+        /* Read the raw little-endian bytes and convert. */
+        if (unpickler_read(self, &pdata, size) < 0)
+            return -1;
+        value = _PyLong_FromByteArray((unsigned char *)pdata, (size_t)size,
+                                      1 /* little endian */ , 1 /* signed */ );
+    }
+    if (value == NULL)
+        return -1;
+    PDATA_PUSH(self->stack, value, -1);
+    return 0;
+}
+
+static int
+load_float(UnpicklerObject *self)
+{
+    PyObject *value;
+    char *endptr, *s;
+    Py_ssize_t len;
+    double d;
+
+    if ((len = unpickler_readline(self, &s)) < 0)
+        return -1;
+    if (len < 2)
+        return bad_readline();
+
+    errno = 0;
+    d = PyOS_ascii_strtod(s, &endptr);
+
+    if (errno || (endptr[0] != '\n') || (endptr[1] != '\0')) {
+        PyErr_SetString(PyExc_ValueError, "could not convert string to float");
+        return -1;
+    }
+
+    if ((value = PyFloat_FromDouble(d)) == NULL)
+        return -1;
+
+    PDATA_PUSH(self->stack, value, -1);
+    return 0;
+}
+
+static int
+load_binfloat(UnpicklerObject *self)
+{
+    PyObject *value;
+    double x;
+    char *s;
+
+    if (unpickler_read(self, &s, 8) < 0)
+        return -1;
+
+    x = _PyFloat_Unpack8((unsigned char *)s, 0);
+    if (x == -1.0 && PyErr_Occurred())
+        return -1;
+
+    if ((value = PyFloat_FromDouble(x)) == NULL)
+        return -1;
+
+    PDATA_PUSH(self->stack, value, -1);
+    return 0;
+}
+
+static int
+load_string(UnpicklerObject *self)
+{
+    PyObject *bytes;
+    PyObject *str = NULL;
+    Py_ssize_t len;
+    char *s, *p;
+
+    if ((len = unpickler_readline(self, &s)) < 0)
+        return -1;
+    if (len < 3)
+        return bad_readline();
+    if ((s = strdup(s)) == NULL) {
+        PyErr_NoMemory();
+        return -1;
+    }
+
+    /* Strip outermost quotes */
+    while (s[len - 1] <= ' ')
+        len--;
+    if (s[0] == '"' && s[len - 1] == '"') {
+        s[len - 1] = '\0';
+        p = s + 1;
+        len -= 2;
+    }
+    else if (s[0] == '\'' && s[len - 1] == '\'') {
+        s[len - 1] = '\0';
+        p = s + 1;
+        len -= 2;
+    }
+    else {
+        free(s);
+        PyErr_SetString(PyExc_ValueError, "insecure string pickle");
+        return -1;
+    }
+
+    /* Use the PyBytes API to decode the string, since that is what is used
+       to encode, and then coerce the result to Unicode. */
+    bytes = PyBytes_DecodeEscape(p, len, NULL, 0, NULL);
+    free(s);
+    if (bytes == NULL)
+        return -1;
+    str = PyUnicode_FromEncodedObject(bytes, self->encoding, self->errors);
+    Py_DECREF(bytes);
+    if (str == NULL)
+        return -1;
+
+    PDATA_PUSH(self->stack, str, -1);
+    return 0;
+}
+
+static int
+load_binbytes(UnpicklerObject *self)
+{
+    PyObject *bytes;
+    long x;
+    char *s;
+
+    if (unpickler_read(self, &s, 4) < 0)
+        return -1;
+
+    x = calc_binint(s, 4);
+    if (x < 0) {
+        PyErr_SetString(UnpicklingError, 
+                        "BINBYTES pickle has negative byte count");
+        return -1;
+    }
+
+    if (unpickler_read(self, &s, x) < 0)
+        return -1;
+    bytes = PyBytes_FromStringAndSize(s, x);
+    if (bytes == NULL)
+        return -1;
+
+    PDATA_PUSH(self->stack, bytes, -1);
+    return 0;
+}
+
+static int
+load_short_binbytes(UnpicklerObject *self)
+{
+    PyObject *bytes;
+    unsigned char x;
+    char *s;
+
+    if (unpickler_read(self, &s, 1) < 0)
+        return -1;
+
+    x = (unsigned char)s[0];
+
+    if (unpickler_read(self, &s, x) < 0)
+        return -1;
+
+    bytes = PyBytes_FromStringAndSize(s, x);
+    if (bytes == NULL)
+        return -1;
+
+    PDATA_PUSH(self->stack, bytes, -1);
+    return 0;
+}
+
+static int
+load_binstring(UnpicklerObject *self)
+{
+    PyObject *str;
+    long x;
+    char *s;
+
+    if (unpickler_read(self, &s, 4) < 0)
+        return -1;
+
+    x = calc_binint(s, 4);
+    if (x < 0) {
+        PyErr_SetString(UnpicklingError, 
+                        "BINSTRING pickle has negative byte count");
+        return -1;
+    }
+
+    if (unpickler_read(self, &s, x) < 0)
+        return -1;
+
+    /* Convert Python 2.x strings to unicode. */
+    str = PyUnicode_Decode(s, x, self->encoding, self->errors);
+    if (str == NULL)
+        return -1;
+
+    PDATA_PUSH(self->stack, str, -1);
+    return 0;
+}
+
+static int
+load_short_binstring(UnpicklerObject *self)
+{
+    PyObject *str;
+    unsigned char x;
+    char *s;
+
+    if (unpickler_read(self, &s, 1) < 0)
+        return -1;
+
+    x = (unsigned char)s[0];
+
+    if (unpickler_read(self, &s, x) < 0)
+        return -1;
+
+    /* Convert Python 2.x strings to unicode. */
+    str = PyUnicode_Decode(s, x, self->encoding, self->errors);
+    if (str == NULL)
+        return -1;
+
+    PDATA_PUSH(self->stack, str, -1);
+    return 0;
+}
+
+static int
+load_unicode(UnpicklerObject *self)
+{
+    PyObject *str;
+    Py_ssize_t len;
+    char *s;
+
+    if ((len = unpickler_readline(self, &s)) < 0)
+        return -1;
+    if (len < 1)
+        return bad_readline();
+
+    str = PyUnicode_DecodeRawUnicodeEscape(s, len - 1, NULL);
+    if (str == NULL)
+        return -1;
+
+    PDATA_PUSH(self->stack, str, -1);
+    return 0;
+}
+
+static int
+load_binunicode(UnpicklerObject *self)
+{
+    PyObject *str;
+    long size;
+    char *s;
+
+    if (unpickler_read(self, &s, 4) < 0)
+        return -1;
+
+    size = calc_binint(s, 4);
+    if (size < 0) {
+        PyErr_SetString(UnpicklingError, 
+                        "BINUNICODE pickle has negative byte count");
+        return -1;
+    }
+
+    if (unpickler_read(self, &s, size) < 0)
+        return -1;
+
+    str = PyUnicode_DecodeUTF8(s, size, NULL);
+    if (str == NULL)
+        return -1;
+
+    PDATA_PUSH(self->stack, str, -1);
+    return 0;
+}
+
+static int
+load_tuple(UnpicklerObject *self)
+{
+    PyObject *tuple;
+    int i;
+
+    if ((i = marker(self)) < 0)
+        return -1;
+
+    tuple = Pdata_poptuple(self->stack, i);
+    if (tuple == NULL)
+        return -1;
+    PDATA_PUSH(self->stack, tuple, -1);
+    return 0;
+}
+
+static int
+load_counted_tuple(UnpicklerObject *self, int len)
+{
+    PyObject *tuple;
+
+    tuple = PyTuple_New(len);
+    if (tuple == NULL)
+        return -1;
+
+    while (--len >= 0) {
+        PyObject *item;
+
+        PDATA_POP(self->stack, item);
+        if (item == NULL)
+            return -1;
+        PyTuple_SET_ITEM(tuple, len, item);
+    }
+    PDATA_PUSH(self->stack, tuple, -1);
+    return 0;
+}
+
+static int
+load_empty_list(UnpicklerObject *self)
+{
+    PyObject *list;
+
+    if ((list = PyList_New(0)) == NULL)
+        return -1;
+    PDATA_PUSH(self->stack, list, -1);
+    return 0;
+}
+
+static int
+load_empty_dict(UnpicklerObject *self)
+{
+    PyObject *dict;
+
+    if ((dict = PyDict_New()) == NULL)
+        return -1;
+    PDATA_PUSH(self->stack, dict, -1);
+    return 0;
+}
+
+static int
+load_list(UnpicklerObject *self)
+{
+    PyObject *list;
+    int i;
+
+    if ((i = marker(self)) < 0)
+        return -1;
+
+    list = Pdata_poplist(self->stack, i);
+    if (list == NULL)
+        return -1;
+    PDATA_PUSH(self->stack, list, -1);
+    return 0;
+}
+
+static int
+load_dict(UnpicklerObject *self)
+{
+    PyObject *dict, *key, *value;
+    int i, j, k;
+
+    if ((i = marker(self)) < 0)
+        return -1;
+    j = self->stack->length;
+
+    if ((dict = PyDict_New()) == NULL)
+        return -1;
+
+    for (k = i + 1; k < j; k += 2) {
+        key = self->stack->data[k - 1];
+        value = self->stack->data[k];
+        if (PyDict_SetItem(dict, key, value) < 0) {
+            Py_DECREF(dict);
+            return -1;
+        }
+    }
+    Pdata_clear(self->stack, i);
+    PDATA_PUSH(self->stack, dict, -1);
+    return 0;
+}
+
+static PyObject *
+instantiate(PyObject *cls, PyObject *args)
+{
+    PyObject *r = NULL;
+
+    /* XXX: The pickle.py module does not create instances this way when the
+       args tuple is empty. See Unpickler._instantiate(). */
+    if ((r = PyObject_CallObject(cls, args)))
+        return r;
+
+    /* XXX: Is this still nescessary? */
+    {
+        PyObject *tp, *v, *tb, *tmp_value;
+
+        PyErr_Fetch(&tp, &v, &tb);
+        tmp_value = v;
+        /* NULL occurs when there was a KeyboardInterrupt */
+        if (tmp_value == NULL)
+            tmp_value = Py_None;
+        if ((r = PyTuple_Pack(3, tmp_value, cls, args))) {
+            Py_XDECREF(v);
+            v = r;
+        }
+        PyErr_Restore(tp, v, tb);
+    }
+    return NULL;
+}
+
+static int
+load_obj(UnpicklerObject *self)
+{
+    PyObject *cls, *args, *obj = NULL;
+    int i;
+
+    if ((i = marker(self)) < 0)
+        return -1;
+
+    args = Pdata_poptuple(self->stack, i + 1);
+    if (args == NULL)
+        return -1;
+
+    PDATA_POP(self->stack, cls);
+    if (cls) {
+        obj = instantiate(cls, args);
+        Py_DECREF(cls);
+    }
+    Py_DECREF(args);
+    if (obj == NULL)
+        return -1;
+
+    PDATA_PUSH(self->stack, obj, -1);
+    return 0;
+}
+
+static int
+load_inst(UnpicklerObject *self)
+{
+    PyObject *cls = NULL;
+    PyObject *args = NULL;
+    PyObject *obj = NULL;
+    PyObject *module_name;
+    PyObject *class_name;
+    Py_ssize_t len;
+    int i;
+    char *s;
+
+    if ((i = marker(self)) < 0)
+        return -1;
+    if ((len = unpickler_readline(self, &s)) < 0)
+        return -1;
+    if (len < 2)
+        return bad_readline();
+
+    /* Here it is safe to use PyUnicode_DecodeASCII(), even though non-ASCII
+       identifiers are permitted in Python 3.0, since the INST opcode is only
+       supported by older protocols on Python 2.x. */
+    module_name = PyUnicode_DecodeASCII(s, len - 1, "strict");
+    if (module_name == NULL)
+        return -1;
+
+    if ((len = unpickler_readline(self, &s)) >= 0) {
+        if (len < 2)
+            return bad_readline();
+        class_name = PyUnicode_DecodeASCII(s, len - 1, "strict");
+        if (class_name == NULL) {
+            cls = find_class(self, module_name, class_name);
+            Py_DECREF(class_name);
+        }
+    }
+    Py_DECREF(module_name);
+
+    if (cls == NULL)
+        return -1;
+
+    if ((args = Pdata_poptuple(self->stack, i)) != NULL) {
+        obj = instantiate(cls, args);
+        Py_DECREF(args);
+    }
+    Py_DECREF(cls);
+
+    if (obj == NULL)
+        return -1;
+
+    PDATA_PUSH(self->stack, obj, -1);
+    return 0;
+}
+
+static int
+load_newobj(UnpicklerObject *self)
+{
+    PyObject *args = NULL;
+    PyObject *clsraw = NULL;
+    PyTypeObject *cls;          /* clsraw cast to its true type */
+    PyObject *obj;
+
+    /* Stack is ... cls argtuple, and we want to call
+     * cls.__new__(cls, *argtuple).
+     */
+    PDATA_POP(self->stack, args);
+    if (args == NULL)
+        goto error;
+    if (!PyTuple_Check(args)) {
+        PyErr_SetString(UnpicklingError, "NEWOBJ expected an arg " "tuple.");
+        goto error;
+    }
+
+    PDATA_POP(self->stack, clsraw);
+    cls = (PyTypeObject *)clsraw;
+    if (cls == NULL)
+        goto error;
+    if (!PyType_Check(cls)) {
+        PyErr_SetString(UnpicklingError, "NEWOBJ class argument "
+                        "isn't a type object");
+        goto error;
+    }
+    if (cls->tp_new == NULL) {
+        PyErr_SetString(UnpicklingError, "NEWOBJ class argument "
+                        "has NULL tp_new");
+        goto error;
+    }
+
+    /* Call __new__. */
+    obj = cls->tp_new(cls, args, NULL);
+    if (obj == NULL)
+        goto error;
+
+    Py_DECREF(args);
+    Py_DECREF(clsraw);
+    PDATA_PUSH(self->stack, obj, -1);
+    return 0;
+
+  error:
+    Py_XDECREF(args);
+    Py_XDECREF(clsraw);
+    return -1;
+}
+
+static int
+load_global(UnpicklerObject *self)
+{
+    PyObject *global = NULL;
+    PyObject *module_name;
+    PyObject *global_name;
+    Py_ssize_t len;
+    char *s;
+
+    if ((len = unpickler_readline(self, &s)) < 0)
+        return -1;
+    if (len < 2)
+        return bad_readline();
+    module_name = PyUnicode_DecodeUTF8(s, len - 1, "strict");
+    if (!module_name)
+        return -1;
+
+    if ((len = unpickler_readline(self, &s)) >= 0) {
+        if (len < 2) {
+            Py_DECREF(module_name);
+            return bad_readline();
+        }
+        global_name = PyUnicode_DecodeUTF8(s, len - 1, "strict");
+        if (global_name) {
+            global = find_class(self, module_name, global_name);
+            Py_DECREF(global_name);
+        }
+    }
+    Py_DECREF(module_name);
+
+    if (global == NULL)
+        return -1;
+    PDATA_PUSH(self->stack, global, -1);
+    return 0;
+}
+
+static int
+load_persid(UnpicklerObject *self)
+{
+    PyObject *pid;
+    Py_ssize_t len;
+    char *s;
+
+    if (self->pers_func) {
+        if ((len = unpickler_readline(self, &s)) < 0)
+            return -1;
+        if (len < 2)
+            return bad_readline();
+
+        pid = PyBytes_FromStringAndSize(s, len - 1);
+        if (pid == NULL)
+            return -1;
+
+        /* Ugh... this does not leak since unpickler_call() steals the
+           reference to pid first. */
+        pid = unpickler_call(self, self->pers_func, pid);
+        if (pid == NULL)
+            return -1;
+
+        PDATA_PUSH(self->stack, pid, -1);
+        return 0;
+    }
+    else {
+        PyErr_SetString(UnpicklingError,
+                        "A load persistent id instruction was encountered,\n"
+                        "but no persistent_load function was specified.");
+        return -1;
+    }
+}
+
+static int
+load_binpersid(UnpicklerObject *self)
+{
+    PyObject *pid;
+
+    if (self->pers_func) {
+        PDATA_POP(self->stack, pid);
+        if (pid == NULL)
+            return -1;
+
+        /* Ugh... this does not leak since unpickler_call() steals the
+           reference to pid first. */
+        pid = unpickler_call(self, self->pers_func, pid);
+        if (pid == NULL)
+            return -1;
+
+        PDATA_PUSH(self->stack, pid, -1);
+        return 0;
+    }
+    else {
+        PyErr_SetString(UnpicklingError,
+                        "A load persistent id instruction was encountered,\n"
+                        "but no persistent_load function was specified.");
+        return -1;
+    }
+}
+
+static int
+load_pop(UnpicklerObject *self)
+{
+    int len;
+
+    if ((len = self->stack->length) <= 0)
+        return stack_underflow();
+
+    /* Note that we split the (pickle.py) stack into two stacks,
+     * an object stack and a mark stack. We have to be clever and
+     * pop the right one. We do this by looking at the top of the
+     * mark stack.
+     */
+
+    if ((self->num_marks > 0) && (self->marks[self->num_marks - 1] == len))
+        self->num_marks--;
+    else {
+        len--;
+        Py_DECREF(self->stack->data[len]);
+        self->stack->length = len;
+    }
+
+    return 0;
+}
+
+static int
+load_pop_mark(UnpicklerObject *self)
+{
+    int i;
+
+    if ((i = marker(self)) < 0)
+        return -1;
+
+    Pdata_clear(self->stack, i);
+
+    return 0;
+}
+
+static int
+load_dup(UnpicklerObject *self)
+{
+    PyObject *last;
+    int len;
+
+    if ((len = self->stack->length) <= 0)
+        return stack_underflow();
+    last = self->stack->data[len - 1];
+    PDATA_APPEND(self->stack, last, -1);
+    return 0;
+}
+
+static int
+load_get(UnpicklerObject *self)
+{
+    PyObject *key, *value;
+    Py_ssize_t len;
+    char *s;
+
+    if ((len = unpickler_readline(self, &s)) < 0)
+        return -1;
+    if (len < 2)
+        return bad_readline();
+
+    key = PyLong_FromString(s, NULL, 10);
+    if (key == NULL)
+        return -1;
+
+    value = PyDict_GetItemWithError(self->memo, key);
+    if (value == NULL) {
+        if (!PyErr_Occurred())
+            PyErr_SetObject(PyExc_KeyError, key);
+        Py_DECREF(key);
+        return -1;
+    }
+    Py_DECREF(key);
+
+    PDATA_APPEND(self->stack, value, -1);
+    return 0;
+}
+
+static int
+load_binget(UnpicklerObject *self)
+{
+    PyObject *key, *value;
+    char *s;
+
+    if (unpickler_read(self, &s, 1) < 0)
+        return -1;
+
+    /* Here, the unsigned cast is necessary to avoid negative values. */
+    key = PyLong_FromLong((long)(unsigned char)s[0]);
+    if (key == NULL)
+        return -1;
+
+    value = PyDict_GetItemWithError(self->memo, key);
+    if (value == NULL) {
+        if (!PyErr_Occurred())
+            PyErr_SetObject(PyExc_KeyError, key);
+        Py_DECREF(key);
+        return -1;
+    }
+    Py_DECREF(key);
+
+    PDATA_APPEND(self->stack, value, -1);
+    return 0;
+}
+
+static int
+load_long_binget(UnpicklerObject *self)
+{
+    PyObject *key, *value;
+    char *s;
+    long k;
+
+    if (unpickler_read(self, &s, 4) < 0)
+        return -1;
+
+    k = (long)(unsigned char)s[0];
+    k |= (long)(unsigned char)s[1] << 8;
+    k |= (long)(unsigned char)s[2] << 16;
+    k |= (long)(unsigned char)s[3] << 24;
+
+    key = PyLong_FromLong(k);
+    if (key == NULL)
+        return -1;
+
+    value = PyDict_GetItemWithError(self->memo, key);
+    if (value == NULL) {
+        if (!PyErr_Occurred())
+            PyErr_SetObject(PyExc_KeyError, key);
+        Py_DECREF(key);
+        return -1;
+    }
+    Py_DECREF(key);
+
+    PDATA_APPEND(self->stack, value, -1);
+    return 0;
+}
+
+/* Push an object from the extension registry (EXT[124]).  nbytes is
+ * the number of bytes following the opcode, holding the index (code) value.
+ */
+static int
+load_extension(UnpicklerObject *self, int nbytes)
+{
+    char *codebytes;            /* the nbytes bytes after the opcode */
+    long code;                  /* calc_binint returns long */
+    PyObject *py_code;          /* code as a Python int */
+    PyObject *obj;              /* the object to push */
+    PyObject *pair;             /* (module_name, class_name) */
+    PyObject *module_name, *class_name;
+
+    assert(nbytes == 1 || nbytes == 2 || nbytes == 4);
+    if (unpickler_read(self, &codebytes, nbytes) < 0)
+        return -1;
+    code = calc_binint(codebytes, nbytes);
+    if (code <= 0) {            /* note that 0 is forbidden */
+        /* Corrupt or hostile pickle. */
+        PyErr_SetString(UnpicklingError, "EXT specifies code <= 0");
+        return -1;
+    }
+
+    /* Look for the code in the cache. */
+    py_code = PyLong_FromLong(code);
+    if (py_code == NULL)
+        return -1;
+    obj = PyDict_GetItem(extension_cache, py_code);
+    if (obj != NULL) {
+        /* Bingo. */
+        Py_DECREF(py_code);
+        PDATA_APPEND(self->stack, obj, -1);
+        return 0;
+    }
+
+    /* Look up the (module_name, class_name) pair. */
+    pair = PyDict_GetItem(inverted_registry, py_code);
+    if (pair == NULL) {
+        Py_DECREF(py_code);
+        PyErr_Format(PyExc_ValueError, "unregistered extension "
+                     "code %ld", code);
+        return -1;
+    }
+    /* Since the extension registry is manipulable via Python code,
+     * confirm that pair is really a 2-tuple of strings.
+     */
+    if (!PyTuple_Check(pair) || PyTuple_Size(pair) != 2 ||
+        !PyUnicode_Check(module_name = PyTuple_GET_ITEM(pair, 0)) ||
+        !PyUnicode_Check(class_name = PyTuple_GET_ITEM(pair, 1))) {
+        Py_DECREF(py_code);
+        PyErr_Format(PyExc_ValueError, "_inverted_registry[%ld] "
+                     "isn't a 2-tuple of strings", code);
+        return -1;
+    }
+    /* Load the object. */
+    obj = find_class(self, module_name, class_name);
+    if (obj == NULL) {
+        Py_DECREF(py_code);
+        return -1;
+    }
+    /* Cache code -> obj. */
+    code = PyDict_SetItem(extension_cache, py_code, obj);
+    Py_DECREF(py_code);
+    if (code < 0) {
+        Py_DECREF(obj);
+        return -1;
+    }
+    PDATA_PUSH(self->stack, obj, -1);
+    return 0;
+}
+
+static int
+load_put(UnpicklerObject *self)
+{
+    PyObject *key, *value;
+    Py_ssize_t len;
+    char *s;
+    int x;
+
+    if ((len = unpickler_readline(self, &s)) < 0)
+        return -1;
+    if (len < 2)
+        return bad_readline();
+    if ((x = self->stack->length) <= 0)
+        return stack_underflow();
+
+    key = PyLong_FromString(s, NULL, 10);
+    if (key == NULL)
+        return -1;
+    value = self->stack->data[x - 1];
+
+    x = PyDict_SetItem(self->memo, key, value);
+    Py_DECREF(key);
+    return x;
+}
+
+static int
+load_binput(UnpicklerObject *self)
+{
+    PyObject *key, *value;
+    char *s;
+    int x;
+
+    if (unpickler_read(self, &s, 1) < 0)
+        return -1;
+    if ((x = self->stack->length) <= 0)
+        return stack_underflow();
+
+    key = PyLong_FromLong((long)(unsigned char)s[0]);
+    if (key == NULL)
+        return -1;
+    value = self->stack->data[x - 1];
+
+    x = PyDict_SetItem(self->memo, key, value);
+    Py_DECREF(key);
+    return x;
+}
+
+static int
+load_long_binput(UnpicklerObject *self)
+{
+    PyObject *key, *value;
+    long k;
+    char *s;
+    int x;
+
+    if (unpickler_read(self, &s, 4) < 0)
+        return -1;
+    if ((x = self->stack->length) <= 0)
+        return stack_underflow();
+
+    k = (long)(unsigned char)s[0];
+    k |= (long)(unsigned char)s[1] << 8;
+    k |= (long)(unsigned char)s[2] << 16;
+    k |= (long)(unsigned char)s[3] << 24;
+
+    key = PyLong_FromLong(k);
+    if (key == NULL)
+        return -1;
+    value = self->stack->data[x - 1];
+
+    x = PyDict_SetItem(self->memo, key, value);
+    Py_DECREF(key);
+    return x;
+}
+
+static int
+do_append(UnpicklerObject *self, int x)
+{
+    PyObject *value;
+    PyObject *list;
+    int len, i;
+
+    len = self->stack->length;
+    if (x > len || x <= 0)
+        return stack_underflow();
+    if (len == x)  /* nothing to do */
+        return 0;
+
+    list = self->stack->data[x - 1];
+
+    if (PyList_Check(list)) {
+        PyObject *slice;
+        Py_ssize_t list_len;
+
+        slice = Pdata_poplist(self->stack, x);
+        if (!slice)
+            return -1;
+        list_len = PyList_GET_SIZE(list);
+        i = PyList_SetSlice(list, list_len, list_len, slice);
+        Py_DECREF(slice);
+        return i;
+    }
+    else {
+        PyObject *append_func;
+
+        append_func = PyObject_GetAttrString(list, "append");
+        if (append_func == NULL)
+            return -1;
+        for (i = x; i < len; i++) {
+            PyObject *result;
+
+            value = self->stack->data[i];
+            result = unpickler_call(self, append_func, value);
+            if (result == NULL) {
+                Pdata_clear(self->stack, i + 1);
+                self->stack->length = x;
+                return -1;
+            }
+            Py_DECREF(result);
+        }
+        self->stack->length = x;
+    }
+
+    return 0;
+}
+
+static int
+load_append(UnpicklerObject *self)
+{
+    return do_append(self, self->stack->length - 1);
+}
+
+static int
+load_appends(UnpicklerObject *self)
+{
+    return do_append(self, marker(self));
+}
+
+static int
+do_setitems(UnpicklerObject *self, int x)
+{
+    PyObject *value, *key;
+    PyObject *dict;
+    int len, i;
+    int status = 0;
+
+    len = self->stack->length;
+    if (x > len || x <= 0)
+        return stack_underflow();
+    if (len == x)  /* nothing to do */
+        return 0;
+    if ((len - x) % 2 != 0) { 
+        /* Currupt or hostile pickle -- we never write one like this. */
+        PyErr_SetString(UnpicklingError, "odd number of items for SETITEMS");
+        return -1;
+    }
+
+    /* Here, dict does not actually need to be a PyDict; it could be anything
+       that supports the __setitem__ attribute. */
+    dict = self->stack->data[x - 1];
+
+    for (i = x + 1; i < len; i += 2) {
+        key = self->stack->data[i - 1];
+        value = self->stack->data[i];
+        if (PyObject_SetItem(dict, key, value) < 0) {
+            status = -1;
+            break;
+        }
+    }
+
+    Pdata_clear(self->stack, x);
+    return status;
+}
+
+static int
+load_setitem(UnpicklerObject *self)
+{
+    return do_setitems(self, self->stack->length - 2);
+}
+
+static int
+load_setitems(UnpicklerObject *self)
+{
+    return do_setitems(self, marker(self));
+}
+
+static int
+load_build(UnpicklerObject *self)
+{
+    PyObject *state, *inst, *slotstate;
+    PyObject *setstate;
+    int status = 0;
+
+    /* Stack is ... instance, state.  We want to leave instance at
+     * the stack top, possibly mutated via instance.__setstate__(state).
+     */
+    if (self->stack->length < 2)
+        return stack_underflow();
+
+    PDATA_POP(self->stack, state);
+    if (state == NULL)
+        return -1;
+
+    inst = self->stack->data[self->stack->length - 1];
+
+    setstate = PyObject_GetAttrString(inst, "__setstate__");
+    if (setstate == NULL && PyErr_ExceptionMatches(PyExc_AttributeError)) {
+        PyErr_Clear();
+    }
+    else {
+        PyObject *result;
+
+        /* The explicit __setstate__ is responsible for everything. */
+        result = unpickler_call(self, setstate, state);
+        Py_DECREF(setstate);
+        if (result == NULL)
+            return -1;
+        Py_DECREF(result);
+        return 0;
+    }
+
+    /* A default __setstate__.  First see whether state embeds a
+     * slot state dict too (a proto 2 addition).
+     */
+    if (PyTuple_Check(state) && Py_SIZE(state) == 2) {
+        PyObject *tmp = state;
+
+        state = PyTuple_GET_ITEM(tmp, 0);
+        slotstate = PyTuple_GET_ITEM(tmp, 1);
+        Py_INCREF(state);
+        Py_INCREF(slotstate);
+        Py_DECREF(tmp);
+    }
+    else
+        slotstate = NULL;
+
+    /* Set inst.__dict__ from the state dict (if any). */
+    if (state != Py_None) {
+        PyObject *dict;
+
+        if (!PyDict_Check(state)) {
+            PyErr_SetString(UnpicklingError, "state is not a dictionary");
+            goto error;
+        }
+        dict = PyObject_GetAttrString(inst, "__dict__");
+        if (dict == NULL)
+            goto error;
+
+        PyDict_Update(dict, state);
+        Py_DECREF(dict);
+    }
+
+    /* Also set instance attributes from the slotstate dict (if any). */
+    if (slotstate != NULL) {
+        PyObject *d_key, *d_value;
+        Py_ssize_t i;
+
+        if (!PyDict_Check(slotstate)) {
+            PyErr_SetString(UnpicklingError,
+                            "slot state is not a dictionary");
+            goto error;
+        }
+        i = 0;
+        while (PyDict_Next(slotstate, &i, &d_key, &d_value)) {
+            if (PyObject_SetAttr(inst, d_key, d_value) < 0)
+                goto error;
+        }
+    }
+
+    if (0) {
+  error:
+        status = -1;
+    }
+
+    Py_DECREF(state);
+    Py_XDECREF(slotstate);
+    return status;
+}
+
+static int
+load_mark(UnpicklerObject *self)
+{
+
+    /* Note that we split the (pickle.py) stack into two stacks, an
+     * object stack and a mark stack. Here we push a mark onto the
+     * mark stack.
+     */
+
+    if ((self->num_marks + 1) >= self->marks_size) {
+        size_t alloc;
+        int *marks;
+
+        /* Use the size_t type to check for overflow. */
+        alloc = ((size_t)self->num_marks << 1) + 20;
+        if (alloc > PY_SSIZE_T_MAX || alloc <= (self->num_marks + 1)) {
+            PyErr_NoMemory();
+            return -1;
+        }
+
+        if (self->marks == NULL)
+            marks = (int *)PyMem_Malloc(alloc * sizeof(int));
+        else
+            marks = (int *)PyMem_Realloc(self->marks, alloc * sizeof(int));
+        if (marks == NULL) {
+            PyErr_NoMemory();
+            return -1;
+        }
+        self->marks = marks;
+        self->marks_size = (Py_ssize_t)alloc;
+    }
+
+    self->marks[self->num_marks++] = self->stack->length;
+
+    return 0;
+}
+
+static int
+load_reduce(UnpicklerObject *self)
+{
+    PyObject *callable = NULL;
+    PyObject *argtup = NULL;
+    PyObject *obj = NULL;
+
+    PDATA_POP(self->stack, argtup);
+    if (argtup == NULL)
+        return -1;
+    PDATA_POP(self->stack, callable);
+    if (callable) {
+        obj = instantiate(callable, argtup);
+        Py_DECREF(callable);
+    }
+    Py_DECREF(argtup);
+
+    if (obj == NULL)
+        return -1;
+
+    PDATA_PUSH(self->stack, obj, -1);
+    return 0;
+}
+
+/* Just raises an error if we don't know the protocol specified.  PROTO
+ * is the first opcode for protocols >= 2.
+ */
+static int
+load_proto(UnpicklerObject *self)
+{
+    char *s;
+    int i;
+
+    if (unpickler_read(self, &s, 1) < 0)
+        return -1;
+
+    i = (unsigned char)s[0];
+    if (i <= HIGHEST_PROTOCOL)
+        return 0;
+
+    PyErr_Format(PyExc_ValueError, "unsupported pickle protocol: %d", i);
+    return -1;
+}
+
+static PyObject *
+load(UnpicklerObject *self)
+{
+    PyObject *err;
+    PyObject *value = NULL;
+    char *s;
+
+    self->num_marks = 0;
+    if (self->stack->length)
+        Pdata_clear(self->stack, 0);
+
+    /* Convenient macros for the dispatch while-switch loop just below. */
+#define OP(opcode, load_func) \
+    case opcode: if (load_func(self) < 0) break; continue;
+
+#define OP_ARG(opcode, load_func, arg) \
+    case opcode: if (load_func(self, (arg)) < 0) break; continue;
+
+    while (1) {
+        if (unpickler_read(self, &s, 1) < 0)
+            break;
+
+        switch ((enum opcode)s[0]) {
+        OP(NONE, load_none)
+        OP(BININT, load_binint)
+        OP(BININT1, load_binint1)
+        OP(BININT2, load_binint2)
+        OP(INT, load_int)
+        OP(LONG, load_long)
+        OP_ARG(LONG1, load_counted_long, 1)
+        OP_ARG(LONG4, load_counted_long, 4)
+        OP(FLOAT, load_float)
+        OP(BINFLOAT, load_binfloat)
+        OP(BINBYTES, load_binbytes)
+        OP(SHORT_BINBYTES, load_short_binbytes)
+        OP(BINSTRING, load_binstring)
+        OP(SHORT_BINSTRING, load_short_binstring)
+        OP(STRING, load_string)
+        OP(UNICODE, load_unicode)
+        OP(BINUNICODE, load_binunicode)
+        OP_ARG(EMPTY_TUPLE, load_counted_tuple, 0)
+        OP_ARG(TUPLE1, load_counted_tuple, 1)
+        OP_ARG(TUPLE2, load_counted_tuple, 2)
+        OP_ARG(TUPLE3, load_counted_tuple, 3)
+        OP(TUPLE, load_tuple)
+        OP(EMPTY_LIST, load_empty_list)
+        OP(LIST, load_list)
+        OP(EMPTY_DICT, load_empty_dict)
+        OP(DICT, load_dict)
+        OP(OBJ, load_obj)
+        OP(INST, load_inst)
+        OP(NEWOBJ, load_newobj)
+        OP(GLOBAL, load_global)
+        OP(APPEND, load_append)
+        OP(APPENDS, load_appends)
+        OP(BUILD, load_build)
+        OP(DUP, load_dup)
+        OP(BINGET, load_binget)
+        OP(LONG_BINGET, load_long_binget)
+        OP(GET, load_get)
+        OP(MARK, load_mark)
+        OP(BINPUT, load_binput)
+        OP(LONG_BINPUT, load_long_binput)
+        OP(PUT, load_put)
+        OP(POP, load_pop)
+        OP(POP_MARK, load_pop_mark)
+        OP(SETITEM, load_setitem)
+        OP(SETITEMS, load_setitems)
+        OP(PERSID, load_persid)
+        OP(BINPERSID, load_binpersid)
+        OP(REDUCE, load_reduce)
+        OP(PROTO, load_proto)
+        OP_ARG(EXT1, load_extension, 1)
+        OP_ARG(EXT2, load_extension, 2)
+        OP_ARG(EXT4, load_extension, 4)
+        OP_ARG(NEWTRUE, load_bool, Py_True)
+        OP_ARG(NEWFALSE, load_bool, Py_False)
+
+        case STOP:
+            break;
+
+        case '\0':
+            PyErr_SetNone(PyExc_EOFError);
+            return NULL;
+
+        default:
+            PyErr_Format(UnpicklingError,
+                         "invalid load key, '%c'.", s[0]);
+            return NULL;
+        }
+
+        break;                  /* and we are done! */
+    }
+
+    /* XXX: It is not clear what this is actually for. */
+    if ((err = PyErr_Occurred())) {
+        if (err == PyExc_EOFError) {
+            PyErr_SetNone(PyExc_EOFError);
+        }
+        return NULL;
+    }
+
+    PDATA_POP(self->stack, value);
+    return value;
+}
+
+PyDoc_STRVAR(Unpickler_load_doc,
+"load() -> object. Load a pickle."
+"\n"
+"Read a pickled object representation from the open file object given in\n"
+"the constructor, and return the reconstituted object hierarchy specified\n"
+"therein.\n");
+
+static PyObject *
+Unpickler_load(UnpicklerObject *self)
+{
+    /* Check whether the Unpickler was initialized correctly. This prevents
+       segfaulting if a subclass overridden __init__ with a function that does
+       not call Unpickler.__init__(). Here, we simply ensure that self->read
+       is not NULL. */
+    if (self->read == NULL) {
+        PyErr_Format(UnpicklingError, 
+                     "Unpickler.__init__() was not called by %s.__init__()",
+                     Py_TYPE(self)->tp_name);
+        return NULL;
+    }
+
+    return load(self);
+}
+
+/* The name of find_class() is misleading. In newer pickle protocols, this
+   function is used for loading any global (i.e., functions), not just
+   classes. The name is kept only for backward compatibility. */
+
+PyDoc_STRVAR(Unpickler_find_class_doc,
+"find_class(module_name, global_name) -> object.\n"
+"\n"
+"Return an object from a specified module, importing the module if\n"
+"necessary.  Subclasses may override this method (e.g. to restrict\n"
+"unpickling of arbitrary classes and functions).\n"
+"\n"
+"This method is called whenever a class or a function object is\n"
+"needed.  Both arguments passed are str objects.\n");
+
+static PyObject *
+Unpickler_find_class(UnpicklerObject *self, PyObject *args)
+{
+    PyObject *global;
+    PyObject *modules_dict;
+    PyObject *module;
+    PyObject *module_name, *global_name;
+
+    if (!PyArg_UnpackTuple(args, "find_class", 2, 2,
+                           &module_name, &global_name))
+        return NULL;
+
+    modules_dict = PySys_GetObject("modules");
+    if (modules_dict == NULL)
+        return NULL;
+
+    module = PyDict_GetItem(modules_dict, module_name);
+    if (module == NULL) {
+        module = PyImport_Import(module_name);
+        if (module == NULL)
+            return NULL;
+        global = PyObject_GetAttr(module, global_name);
+        Py_DECREF(module);
+    }
+    else { 
+        global = PyObject_GetAttr(module, global_name);
+    }
+    return global;
+}
+
+static struct PyMethodDef Unpickler_methods[] = {
+    {"load", (PyCFunction)Unpickler_load, METH_NOARGS,
+     Unpickler_load_doc},
+    {"find_class", (PyCFunction)Unpickler_find_class, METH_VARARGS,
+     Unpickler_find_class_doc},
+    {NULL, NULL}                /* sentinel */
+};
+
+static void
+Unpickler_dealloc(UnpicklerObject *self)
+{
+    PyObject_GC_UnTrack((PyObject *)self);
+    Py_XDECREF(self->readline);
+    Py_XDECREF(self->read);
+    Py_XDECREF(self->memo);
+    Py_XDECREF(self->stack);
+    Py_XDECREF(self->pers_func);
+    Py_XDECREF(self->arg);
+    Py_XDECREF(self->last_string);
+
+    PyMem_Free(self->marks);
+    free(self->encoding);
+    free(self->errors);
+
+    Py_TYPE(self)->tp_free((PyObject *)self);
+}
+
+static int
+Unpickler_traverse(UnpicklerObject *self, visitproc visit, void *arg)
+{
+    Py_VISIT(self->readline);
+    Py_VISIT(self->read);
+    Py_VISIT(self->memo);
+    Py_VISIT(self->stack);
+    Py_VISIT(self->pers_func);
+    Py_VISIT(self->arg);
+    Py_VISIT(self->last_string);
+    return 0;
+}
+
+static int
+Unpickler_clear(UnpicklerObject *self)
+{
+    Py_CLEAR(self->readline);
+    Py_CLEAR(self->read);
+    Py_CLEAR(self->memo);
+    Py_CLEAR(self->stack);
+    Py_CLEAR(self->pers_func);
+    Py_CLEAR(self->arg);
+    Py_CLEAR(self->last_string);
+
+    PyMem_Free(self->marks);
+    self->marks = NULL;
+    free(self->encoding);
+    self->encoding = NULL;
+    free(self->errors);
+    self->errors = NULL;
+
+    return 0;
+}
+
+PyDoc_STRVAR(Unpickler_doc,
+"Unpickler(file, *, encoding='ASCII', errors='strict')"
+"\n"
+"This takes a binary file for reading a pickle data stream.\n"
+"\n"
+"The protocol version of the pickle is detected automatically, so no\n"
+"proto argument is needed.\n"
+"\n"
+"The file-like object must have two methods, a read() method\n"
+"that takes an integer argument, and a readline() method that\n"
+"requires no arguments.  Both methods should return bytes.\n"
+"Thus file-like object can be a binary file object opened for\n"
+"reading, a BytesIO object, or any other custom object that\n"
+"meets this interface.\n"
+"\n"
+"Optional keyword arguments are encoding and errors, which are\n"
+"used to decode 8-bit string instances pickled by Python 2.x.\n"
+"These default to 'ASCII' and 'strict', respectively.\n");
+
+static int
+Unpickler_init(UnpicklerObject *self, PyObject *args, PyObject *kwds)
+{
+    static char *kwlist[] = {"file", "encoding", "errors", 0};
+    PyObject *file;
+    char *encoding = NULL;
+    char *errors = NULL;
+
+    /* XXX: That is an horrible error message. But, I don't know how to do
+       better... */
+    if (Py_SIZE(args) != 1) {
+        PyErr_Format(PyExc_TypeError,
+                     "%s takes exactly one positional argument (%zd given)",
+                     Py_TYPE(self)->tp_name, Py_SIZE(args));
+        return -1;
+    }
+
+    /* Arguments parsing needs to be done in the __init__() method to allow
+       subclasses to define their own __init__() method, which may (or may
+       not) support Unpickler arguments. However, this means we need to be
+       extra careful in the other Unpickler methods, since a subclass could
+       forget to call Unpickler.__init__() thus breaking our internal
+       invariants. */
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|ss:Unpickler", kwlist,
+                                     &file, &encoding, &errors))
+        return -1;
+
+    /* In case of multiple __init__() calls, clear previous content. */
+    if (self->read != NULL)
+        (void)Unpickler_clear(self);
+
+    self->read = PyObject_GetAttrString(file, "read");
+    self->readline = PyObject_GetAttrString(file, "readline");
+    if (self->readline == NULL || self->read == NULL)
+        return -1;
+
+    if (encoding == NULL)
+        encoding = "ASCII";
+    if (errors == NULL)
+        errors = "strict";
+
+    self->encoding = strdup(encoding);
+    self->errors = strdup(errors);
+    if (self->encoding == NULL || self->errors == NULL) {
+        PyErr_NoMemory();
+        return -1;
+    }
+
+    if (PyObject_HasAttrString((PyObject *)self, "persistent_load")) {
+        self->pers_func = PyObject_GetAttrString((PyObject *)self,
+                                                 "persistent_load");
+        if (self->pers_func == NULL)
+            return -1;
+    }
+    else {
+        self->pers_func = NULL;
+    }
+
+    self->stack = (Pdata *)Pdata_New();
+    if (self->stack == NULL)
+        return -1;
+
+    self->memo = PyDict_New();
+    if (self->memo == NULL)
+        return -1;
+
+    return 0;
+}
+
+static PyObject *
+Unpickler_get_memo(UnpicklerObject *self)
+{
+    if (self->memo == NULL)
+        PyErr_SetString(PyExc_AttributeError, "memo");
+    else
+        Py_INCREF(self->memo);
+    return self->memo;
+}
+
+static int
+Unpickler_set_memo(UnpicklerObject *self, PyObject *value)
+{
+    PyObject *tmp;
+
+    if (value == NULL) {
+        PyErr_SetString(PyExc_TypeError,
+                        "attribute deletion is not supported");
+        return -1;
+    }
+    if (!PyDict_Check(value)) {
+        PyErr_SetString(PyExc_TypeError, "memo must be a dictionary");
+        return -1;
+    }
+
+    tmp = self->memo;
+    Py_INCREF(value);
+    self->memo = value;
+    Py_XDECREF(tmp);
+
+    return 0;
+}
+
+static PyObject *
+Unpickler_get_persload(UnpicklerObject *self)
+{
+    if (self->pers_func == NULL)
+        PyErr_SetString(PyExc_AttributeError, "persistent_load");
+    else
+        Py_INCREF(self->pers_func);
+    return self->pers_func;
+}
+
+static int
+Unpickler_set_persload(UnpicklerObject *self, PyObject *value)
+{
+    PyObject *tmp;
+
+    if (value == NULL) {
+        PyErr_SetString(PyExc_TypeError,
+                        "attribute deletion is not supported");
+        return -1;
+    }
+    if (!PyCallable_Check(value)) {
+        PyErr_SetString(PyExc_TypeError,
+                        "persistent_load must be a callable taking "
+                        "one argument");
+        return -1;
+    }
+
+    tmp = self->pers_func;
+    Py_INCREF(value);
+    self->pers_func = value;
+    Py_XDECREF(tmp);      /* self->pers_func can be NULL, so be careful. */
+
+    return 0;
+}
+
+static PyGetSetDef Unpickler_getsets[] = {
+    {"memo", (getter)Unpickler_get_memo, (setter)Unpickler_set_memo},
+    {"persistent_load", (getter)Unpickler_get_persload,
+                        (setter)Unpickler_set_persload},
+    {NULL}
+};
+
+static PyTypeObject Unpickler_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "_pickle.Unpickler",                /*tp_name*/
+    sizeof(UnpicklerObject),            /*tp_basicsize*/
+    0,                                  /*tp_itemsize*/
+    (destructor)Unpickler_dealloc,      /*tp_dealloc*/
+    0,                                  /*tp_print*/
+    0,                                  /*tp_getattr*/
+    0,	                                /*tp_setattr*/
+    0,                                  /*tp_compare*/
+    0,                                  /*tp_repr*/
+    0,                                  /*tp_as_number*/
+    0,                                  /*tp_as_sequence*/
+    0,                                  /*tp_as_mapping*/
+    0,                                  /*tp_hash*/
+    0,                                  /*tp_call*/
+    0,                                  /*tp_str*/
+    0,                                  /*tp_getattro*/
+    0,                                  /*tp_setattro*/
+    0,                                  /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,
+    Unpickler_doc,                      /*tp_doc*/
+    (traverseproc)Unpickler_traverse,   /*tp_traverse*/
+    (inquiry)Unpickler_clear,           /*tp_clear*/
+    0,                                  /*tp_richcompare*/
+    0,                                  /*tp_weaklistoffset*/
+    0,                                  /*tp_iter*/
+    0,                                  /*tp_iternext*/
+    Unpickler_methods,                  /*tp_methods*/
+    0,                                  /*tp_members*/
+    Unpickler_getsets,                  /*tp_getset*/
+    0,                                  /*tp_base*/
+    0,                                  /*tp_dict*/
+    0,                                  /*tp_descr_get*/
+    0,                                  /*tp_descr_set*/
+    0,                                  /*tp_dictoffset*/
+    (initproc)Unpickler_init,           /*tp_init*/
+    PyType_GenericAlloc,                /*tp_alloc*/
+    PyType_GenericNew,                  /*tp_new*/
+    PyObject_GC_Del,                    /*tp_free*/
+    0,                                  /*tp_is_gc*/
+};
+
+static int
+init_stuff(void)
+{
+    PyObject *copyreg;
+
+    copyreg = PyImport_ImportModule("copyreg");
+    if (!copyreg)
+        return -1;
+
+    dispatch_table = PyObject_GetAttrString(copyreg, "dispatch_table");
+    if (!dispatch_table)
+        goto error;
+
+    extension_registry = \
+        PyObject_GetAttrString(copyreg, "_extension_registry");
+    if (!extension_registry)
+        goto error;
+
+    inverted_registry = PyObject_GetAttrString(copyreg, "_inverted_registry");
+    if (!inverted_registry)
+        goto error;
+
+    extension_cache = PyObject_GetAttrString(copyreg, "_extension_cache");
+    if (!extension_cache)
+        goto error;
+
+    Py_DECREF(copyreg);
+
+    empty_tuple = PyTuple_New(0);
+    if (empty_tuple == NULL)
+        return -1;
+
+    two_tuple = PyTuple_New(2);
+    if (two_tuple == NULL)
+        return -1;
+    /* We use this temp container with no regard to refcounts, or to
+     * keeping containees alive.  Exempt from GC, because we don't
+     * want anything looking at two_tuple() by magic.
+     */
+    PyObject_GC_UnTrack(two_tuple);
+
+    return 0;
+
+  error:
+    Py_DECREF(copyreg);
+    return -1;
+}
+
+static struct PyModuleDef _picklemodule = {
+    PyModuleDef_HEAD_INIT,
+    "_pickle",
+    pickle_module_doc,
+    -1,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    NULL
+};
+
+PyMODINIT_FUNC
+PyInit__pickle(void)
+{
+    PyObject *m;
+
+    if (PyType_Ready(&Unpickler_Type) < 0)
+        return NULL;
+    if (PyType_Ready(&Pickler_Type) < 0)
+        return NULL;
+    if (PyType_Ready(&Pdata_Type) < 0)
+        return NULL;
+
+    /* Create the module and add the functions. */
+    m = PyModule_Create(&_picklemodule);
+    if (m == NULL)
+        return NULL;
+
+    if (PyModule_AddObject(m, "Pickler", (PyObject *)&Pickler_Type) < 0)
+        return NULL;
+    if (PyModule_AddObject(m, "Unpickler", (PyObject *)&Unpickler_Type) < 0)
+        return NULL;
+
+    /* Initialize the exceptions. */
+    PickleError = PyErr_NewException("_pickle.PickleError", NULL, NULL);
+    if (PickleError == NULL)
+        return NULL;
+    PicklingError = \
+        PyErr_NewException("_pickle.PicklingError", PickleError, NULL);
+    if (PicklingError == NULL)
+        return NULL;
+    UnpicklingError = \
+        PyErr_NewException("_pickle.UnpicklingError", PickleError, NULL);
+    if (UnpicklingError == NULL)
+        return NULL;
+
+    if (PyModule_AddObject(m, "PickleError", PickleError) < 0)
+        return NULL;
+    if (PyModule_AddObject(m, "PicklingError", PicklingError) < 0)
+        return NULL;
+    if (PyModule_AddObject(m, "UnpicklingError", UnpicklingError) < 0)
+        return NULL;
+
+    if (init_stuff() < 0)
+        return NULL;
+
+    return m;
+}
diff --git a/setup.py b/setup.py
index 171b128..54868fe 100644
--- a/setup.py
+++ b/setup.py
@@ -422,6 +422,8 @@
         exts.append( Extension("_functools", ["_functoolsmodule.c"]) )
         # Memory-based IO accelerator modules
         exts.append( Extension("_bytesio", ["_bytesio.c"]) )
+        # C-optimized pickle replacement
+        exts.append( Extension("_pickle", ["_pickle.c"]) )
         # atexit
         exts.append( Extension("atexit", ["atexitmodule.c"]) )
         # _json speedups