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.

1 files changed, 40 insertions, 0 deletions

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 @@ extern DL_IMPORT(unsigned LONG_LONG) PyLong_AsUnsignedLongLong(PyObject *);
 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