[Python-checkins] CVS: python/dist/src/Include longobject.h,2.19,2.20

[Tim Peters]

Update of /cvsroot/python/python/dist/src/Include
In directory usw-pr-cvs1:/tmp/cvs-serv17866/python/dist/src/Include

Modified Files:
	longobject.h 
Log Message:
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.


Index: longobject.h
===================================================================
RCS file: /cvsroot/python/python/dist/src/Include/longobject.h,v
retrieving revision 2.19
retrieving revision 2.20
diff -C2 -r2.19 -r2.20
*** longobject.h	2000/09/26 05:45:59	2.19
--- longobject.h	2001/06/11 21:23:58	2.20
***************
*** 45,48 ****
--- 45,88 ----
  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
  }