Two new private longobject API functions,
_PyLong_FromByteArray
_PyLong_AsByteArray
Untested and probably buggy -- they compile OK, but nothing calls them
yet. Will soon be called by the struct module, to implement x-platform
'q' and 'Q'.
If other people have uses for them, we could move them into the public API.
See longobject.h for usage details.
diff --git a/Include/longobject.h b/Include/longobject.h
index 7ebceec..3c6fde0 100644
--- a/Include/longobject.h
+++ b/Include/longobject.h
@@ -44,6 +44,46 @@
DL_IMPORT(PyObject *) PyLong_FromString(char *, char **, int);
DL_IMPORT(PyObject *) PyLong_FromUnicode(Py_UNICODE*, int, int);
+/* _PyLong_FromByteArray: View the n unsigned bytes as a binary integer in
+ base 256, and return a Python long with the same numeric value.
+ If n is 0, the integer is 0. Else:
+ If little_endian is 1/true, bytes[n-1] is the MSB and bytes[0] the LSB;
+ else (little_endian is 0/false) bytes[0] is the MSB and bytes[n-1] the
+ LSB.
+ If is_signed is 0/false, view the bytes as a non-negative integer.
+ If is_signed is 1/true, view the bytes as a 2's-complement integer,
+ non-negative if bit 0x80 of the MSB is clear, negative if set.
+ Error returns:
+ + Return NULL with the appropriate exception set if there's not
+ enough memory to create the Python long.
+*/
+extern DL_IMPORT(PyObject *) _PyLong_FromByteArray(
+ const unsigned char* bytes, size_t n,
+ int little_endian, int is_signed);
+
+/* _PyLong_AsByteArray: Convert the least-significant 8*n bits of long
+ v to a base-256 integer, stored in array bytes. Normally return 0,
+ return -1 on error.
+ If little_endian is 1/true, store the MSB at bytes[n-1] and the LSB at
+ bytes[0]; else (little_endian is 0/false) store the MSB at bytes[0] and
+ the LSB at bytes[n-1].
+ If is_signed is 0/false, it's an error if v < 0; else (v >= 0) n bytes
+ are filled and there's nothing special about bit 0x80 of the MSB.
+ If is_signed is 1/true, bytes is filled with the 2's-complement
+ representation of v's value. Bit 0x80 of the MSB is the sign bit.
+ Error returns (-1):
+ + is_signed is 0 and v < 0. TypeError is set in this case, and bytes
+ isn't altered.
+ + n isn't big enough to hold the full mathematical value of v. For
+ example, if is_signed is 0 and there are more digits in the v than
+ fit in n; or if is_signed is 1, v < 0, and n is just 1 bit shy of
+ being large enough to hold a sign bit. OverflowError is set in this
+ case, but bytes holds the least-signficant n bytes of the true value.
+*/
+extern DL_IMPORT(int) _PyLong_AsByteArray(PyLongObject* v,
+ unsigned char* bytes, size_t n,
+ int little_endian, int is_signed);
+
#ifdef __cplusplus
}
#endif