[Python-checkins] python/dist/src/Include floatobject.h,2.21,2.22

[tim_one@users.sourceforge.net]

Update of /cvsroot/python/python/dist/src/Include
In directory sc8-pr-cvs1:/tmp/cvs-serv6732/python/Include

Modified Files:
	floatobject.h 
Log Message:
New private API functions _PyFloat_{Pack,Unpack}(4,8}.  This is a
refactoring to get all the duplicates of this delicate code out of the
cPickle and struct modules.


Index: floatobject.h
===================================================================
RCS file: /cvsroot/python/python/dist/src/Include/floatobject.h,v
retrieving revision 2.21
retrieving revision 2.22
diff -C2 -d -r2.21 -r2.22
*** floatobject.h	12 Aug 2002 07:21:56 -0000	2.21
--- floatobject.h	20 Mar 2003 20:53:29 -0000	2.22
***************
*** 48,51 ****
--- 48,93 ----
  PyAPI_FUNC(void) PyFloat_AsString(char*, PyFloatObject *v);
  
+ /* _PyFloat_{Pack,Unpack}{4,8}
+  *
+  * The struct and pickle (at least) modules need an efficient platform-
+  * independent way to store floating-point values as byte strings.
+  * The Pack routines produce a string from a C double, and the Unpack
+  * routines produce a C double from such a string.  The suffix (4 or 8)
+  * specifies the number of bytes in the string.
+  *
+  * Excepting NaNs and infinities (which aren't handled correctly), the 4-
+  * byte format is identical to the IEEE-754 single precision format, and
+  * the 8-byte format to the IEEE-754 double precision format.  On non-
+  * IEEE platforms with more precision, or larger dynamic range, than
+  * 754 supports, not all values can be packed; on non-IEEE platforms with
+  * less precision, or smaller dynamic range, not all values can be
+  * unpacked.  What happens in such cases is partly accidental (alas).
+  */
+ 
+ /* The pack routines write 4 or 8 bytes, starting at p.  le is a bool
+  * argument, true if you want the string in little-endian format (exponent
+  * last, at p+3 or p+7), false if you want big-endian format (exponent
+  * first, at p).
+  * Return value:  0 if all is OK, -1 if error (and an exception is
+  * set, most likely OverflowError).
+  * Bug:  What this does is undefined if x is a NaN or infinity.
+  * Bug:  -0.0 and +0.0 produce the same string.
+  */
+ PyAPI_FUNC(int) _PyFloat_Pack4(double x, unsigned char *p, int le);
+ PyAPI_FUNC(int) _PyFloat_Pack8(double x, unsigned char *p, int le);
+ 
+ /* The unpack routines read 4 or 8 bytes, starting at p.  le is a bool
+  * argument, true if the string is in little-endian format (exponent
+  * last, at p+3 or p+7), false if big-endian (exponent first, at p).
+  * Return value:  The unpacked double.  On error, this is -1.0 and
+  * PyErr_Occurred() is true (and an exception is set, most likely
+  * OverflowError).
+  * Bug:  What this does is undefined if the string represents a NaN or
+  * infinity.
+  */
+ PyAPI_FUNC(double) _PyFloat_Unpack4(const unsigned char *p, int le);
+ PyAPI_FUNC(double) _PyFloat_Unpack8(const unsigned char *p, int le);
+ 
+ 
  #ifdef __cplusplus
  }