cpython/Parser/bitset.c

67 lines
949 B
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++;
}