Issue #4258:  Make it possible to use 30-bit digits for PyLongs:
 - new configure option --enable-big-digits
 - new structseq sys.int_info giving information about the internal format
By default, 30-bit digits are enabled on 64-bit machines but
disabled on 32-bit machines.
diff --git a/configure b/configure
index c83ae88..85db6d6 100755
--- a/configure
+++ b/configure
@@ -1320,6 +1320,8 @@
   --enable-profiling      enable C-level code profiling
   --enable-ipv6           Enable ipv6 (with ipv4) support
   --disable-ipv6          Disable ipv6 support
+  --enable-big-digits[=BITS]
+                          use big digits for Python longs [BITS=30]
 
 Optional Packages:
   --with-PACKAGE[=ARG]    use PACKAGE [ARG=yes]
@@ -6965,6 +6967,386 @@
 
 fi
 
+
+  { echo "$as_me:$LINENO: checking for uint32_t" >&5
+echo $ECHO_N "checking for uint32_t... $ECHO_C" >&6; }
+if test "${ac_cv_c_uint32_t+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  ac_cv_c_uint32_t=no
+     for ac_type in 'uint32_t' 'unsigned int' 'unsigned long int' \
+	 'unsigned long long int' 'unsigned short int' 'unsigned char'; do
+       cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+$ac_includes_default
+int
+main ()
+{
+static int test_array [1 - 2 * !(($ac_type) -1 >> (32 - 1) == 1)];
+test_array [0] = 0
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  case $ac_type in
+  uint32_t) ac_cv_c_uint32_t=yes ;;
+  *) ac_cv_c_uint32_t=$ac_type ;;
+esac
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+       test "$ac_cv_c_uint32_t" != no && break
+     done
+fi
+{ echo "$as_me:$LINENO: result: $ac_cv_c_uint32_t" >&5
+echo "${ECHO_T}$ac_cv_c_uint32_t" >&6; }
+  case $ac_cv_c_uint32_t in #(
+  no|yes) ;; #(
+  *)
+
+cat >>confdefs.h <<\_ACEOF
+#define _UINT32_T 1
+_ACEOF
+
+
+cat >>confdefs.h <<_ACEOF
+#define uint32_t $ac_cv_c_uint32_t
+_ACEOF
+;;
+  esac
+
+
+  { echo "$as_me:$LINENO: checking for uint64_t" >&5
+echo $ECHO_N "checking for uint64_t... $ECHO_C" >&6; }
+if test "${ac_cv_c_uint64_t+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  ac_cv_c_uint64_t=no
+     for ac_type in 'uint64_t' 'unsigned int' 'unsigned long int' \
+	 'unsigned long long int' 'unsigned short int' 'unsigned char'; do
+       cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+$ac_includes_default
+int
+main ()
+{
+static int test_array [1 - 2 * !(($ac_type) -1 >> (64 - 1) == 1)];
+test_array [0] = 0
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  case $ac_type in
+  uint64_t) ac_cv_c_uint64_t=yes ;;
+  *) ac_cv_c_uint64_t=$ac_type ;;
+esac
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+       test "$ac_cv_c_uint64_t" != no && break
+     done
+fi
+{ echo "$as_me:$LINENO: result: $ac_cv_c_uint64_t" >&5
+echo "${ECHO_T}$ac_cv_c_uint64_t" >&6; }
+  case $ac_cv_c_uint64_t in #(
+  no|yes) ;; #(
+  *)
+
+cat >>confdefs.h <<\_ACEOF
+#define _UINT64_T 1
+_ACEOF
+
+
+cat >>confdefs.h <<_ACEOF
+#define uint64_t $ac_cv_c_uint64_t
+_ACEOF
+;;
+  esac
+
+
+  { echo "$as_me:$LINENO: checking for int32_t" >&5
+echo $ECHO_N "checking for int32_t... $ECHO_C" >&6; }
+if test "${ac_cv_c_int32_t+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  ac_cv_c_int32_t=no
+     for ac_type in 'int32_t' 'int' 'long int' \
+	 'long long int' 'short int' 'signed char'; do
+       cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+$ac_includes_default
+int
+main ()
+{
+static int test_array [1 - 2 * !(0 < ($ac_type) (((($ac_type) 1 << (32 - 2)) - 1) * 2 + 1))];
+test_array [0] = 0
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+$ac_includes_default
+int
+main ()
+{
+static int test_array [1 - 2 * !(($ac_type) (((($ac_type) 1 << (32 - 2)) - 1) * 2 + 1)
+	         < ($ac_type) (((($ac_type) 1 << (32 - 2)) - 1) * 2 + 2))];
+test_array [0] = 0
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  :
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	case $ac_type in
+  int32_t) ac_cv_c_int32_t=yes ;;
+  *) ac_cv_c_int32_t=$ac_type ;;
+esac
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+       test "$ac_cv_c_int32_t" != no && break
+     done
+fi
+{ echo "$as_me:$LINENO: result: $ac_cv_c_int32_t" >&5
+echo "${ECHO_T}$ac_cv_c_int32_t" >&6; }
+  case $ac_cv_c_int32_t in #(
+  no|yes) ;; #(
+  *)
+
+cat >>confdefs.h <<_ACEOF
+#define int32_t $ac_cv_c_int32_t
+_ACEOF
+;;
+  esac
+
+
+  { echo "$as_me:$LINENO: checking for int64_t" >&5
+echo $ECHO_N "checking for int64_t... $ECHO_C" >&6; }
+if test "${ac_cv_c_int64_t+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  ac_cv_c_int64_t=no
+     for ac_type in 'int64_t' 'int' 'long int' \
+	 'long long int' 'short int' 'signed char'; do
+       cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+$ac_includes_default
+int
+main ()
+{
+static int test_array [1 - 2 * !(0 < ($ac_type) (((($ac_type) 1 << (64 - 2)) - 1) * 2 + 1))];
+test_array [0] = 0
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+$ac_includes_default
+int
+main ()
+{
+static int test_array [1 - 2 * !(($ac_type) (((($ac_type) 1 << (64 - 2)) - 1) * 2 + 1)
+	         < ($ac_type) (((($ac_type) 1 << (64 - 2)) - 1) * 2 + 2))];
+test_array [0] = 0
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  :
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	case $ac_type in
+  int64_t) ac_cv_c_int64_t=yes ;;
+  *) ac_cv_c_int64_t=$ac_type ;;
+esac
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+       test "$ac_cv_c_int64_t" != no && break
+     done
+fi
+{ echo "$as_me:$LINENO: result: $ac_cv_c_int64_t" >&5
+echo "${ECHO_T}$ac_cv_c_int64_t" >&6; }
+  case $ac_cv_c_int64_t in #(
+  no|yes) ;; #(
+  *)
+
+cat >>confdefs.h <<_ACEOF
+#define int64_t $ac_cv_c_int64_t
+_ACEOF
+;;
+  esac
+
 { echo "$as_me:$LINENO: checking for ssize_t" >&5
 echo $ECHO_N "checking for ssize_t... $ECHO_C" >&6; }
 if test "${ac_cv_type_ssize_t+set}" = set; then
@@ -21687,6 +22069,37 @@
 
 LIBS=$LIBS_SAVE
 
+# determine what size digit to use for Python's longs
+{ echo "$as_me:$LINENO: checking digit size for Python's longs" >&5
+echo $ECHO_N "checking digit size for Python's longs... $ECHO_C" >&6; }
+# Check whether --enable-big-digits was given.
+if test "${enable_big_digits+set}" = set; then
+  enableval=$enable_big_digits; case $enable_big_digits in
+yes)
+  enable_big_digits=30 ;;
+no)
+  enable_big_digits=15 ;;
+15|30)
+  ;;
+*)
+  { { echo "$as_me:$LINENO: error: bad value $enable_big_digits for --enable-big-digits; value should be 15 or 30" >&5
+echo "$as_me: error: bad value $enable_big_digits for --enable-big-digits; value should be 15 or 30" >&2;}
+   { (exit 1); exit 1; }; } ;;
+esac
+{ echo "$as_me:$LINENO: result: $enable_big_digits" >&5
+echo "${ECHO_T}$enable_big_digits" >&6; }
+
+cat >>confdefs.h <<_ACEOF
+#define PYLONG_BITS_IN_DIGIT $enable_big_digits
+_ACEOF
+
+
+else
+  { echo "$as_me:$LINENO: result: no value specified" >&5
+echo "${ECHO_T}no value specified" >&6; }
+fi
+
+
 # check for wchar.h
 if test "${ac_cv_header_wchar_h+set}" = set; then
   { echo "$as_me:$LINENO: checking for wchar.h" >&5