Added new private API function _PyLong_NumBits. This will be used at the

start for the C implemention of new pickle LONG1 and LONG4 opcodes (the
linear-time way to pickle a long is to call _PyLong_AsByteArray, but
the caller has no idea how big an array to allocate, and correct
calculation is a bit subtle).

1 files changed, 11 insertions, 0 deletions

diff --git a/Include/longobject.h b/Include/longobject.h
index e452f516..3b808fb 100644
--- a/Include/longobject.h
+++ b/Include/longobject.h
@@ -44,6 +44,17 @@ PyAPI_FUNC(PyObject *) PyLong_FromString(char *, char **, int);
 PyAPI_FUNC(PyObject *) PyLong_FromUnicode(Py_UNICODE*, int, int);
 #endif
 
+/* _PyLong_NumBits.  Return the number of bits needed to represent a long
+   in contiguous 2's-complement form, including 1 for the sign bit.  For
+   example, this returns 1 for 0, and 2 for 1 and -1.  Note that the
+   ceiling of this divided by 8 is the number of bytes needed by
+   _PyLong_AsByteArray to store the long in 256's-complement form.
+   v must not be NULL, and must be a normalized long.
+   (size_t)-1 is returned and OverflowError set if the true result doesn't
+   fit in a size_t.
+*/
+PyAPI_FUNC(size_t) _PyLong_NumBits(PyObject *v);
+
 /* _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: