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v0.5.1
https://github.com/python/cpython
09 December 2020, 11:06:31 UTC
Revision a40c793d06ee2b42a5013015352616b4ca6b288b authored by Tim Peters on 05 September 2001, 22:36:56 UTC, committed by Tim Peters on 05 September 2001, 22:36:56 UTC 
Rework the way we try to check for libm overflow, given that C99 no longer
 
requires that errno ever get set, and it looks like glibc is already
playing that game.  New rules:

+ Never use HUGE_VAL.  Use the new Py_HUGE_VAL instead.

+ Never believe errno.  If overflow is the only thing you're interested in,
  use the new Py_OVERFLOWED(x) macro.  If you're interested in any libm
  errors, use the new Py_SET_ERANGE_IF_OVERFLOW(x) macro, which attempts
  to set errno the way C89 said it worked.

Unfortunately, none of these are reliable, but they work on Windows and I
*expect* under glibc too.
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Tip revision: a40c793d06ee2b42a5013015352616b4ca6b288b authored by Tim Peters on 05 September 2001, 22:36:56 UTC
Rework the way we try to check for libm overflow, given that C99 no longer
Tip revision: a40c793
bitset.c 

/* Bitset primitives used by the parser generator */

#include "pgenheaders.h"
#include "bitset.h"

bitset
newbitset(int nbits)
{
	int nbytes = NBYTES(nbits);
	bitset ss = PyMem_NEW(BYTE, nbytes);
	
	if (ss == NULL)
		Py_FatalError("no mem for bitset");
	
	ss += nbytes;
	while (--nbytes >= 0)
		*--ss = 0;
	return ss;
}

void
delbitset(bitset ss)
{
	PyMem_DEL(ss);
}

int
addbit(bitset ss, int ibit)
{
	int ibyte = BIT2BYTE(ibit);
	BYTE mask = BIT2MASK(ibit);
	
	if (ss[ibyte] & mask)
		return 0; /* Bit already set */
	ss[ibyte] |= mask;
	return 1;
}

#if 0 /* Now a macro */
int
testbit(bitset ss, int ibit)
{
	return (ss[BIT2BYTE(ibit)] & BIT2MASK(ibit)) != 0;
}
#endif

int
samebitset(bitset ss1, bitset ss2, int nbits)
{
	int i;
	
	for (i = NBYTES(nbits); --i >= 0; )
		if (*ss1++ != *ss2++)
			return 0;
	return 1;
}

void
mergebitset(bitset ss1, bitset ss2, int nbits)
{
	int i;
	
	for (i = NBYTES(nbits); --i >= 0; )
		*ss1++ |= *ss2++;
}
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