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/Parser/bitset.c

http://unladen-swallow.googlecode.com/
C | 66 lines | 52 code | 13 blank | 1 comment | 9 complexity | eac35f096816dd44570f9fc1d07709e0 MD5 | raw file
 1
 2/* Bitset primitives used by the parser generator */
 3
 4#include "pgenheaders.h"
 5#include "bitset.h"
 6
 7bitset
 8newbitset(int nbits)
 9{
10	int nbytes = NBYTES(nbits);
11	bitset ss = (char *)PyObject_MALLOC(sizeof(BYTE) *  nbytes);
12	
13	if (ss == NULL)
14		Py_FatalError("no mem for bitset");
15	
16	ss += nbytes;
17	while (--nbytes >= 0)
18		*--ss = 0;
19	return ss;
20}
21
22void
23delbitset(bitset ss)
24{
25	PyObject_FREE(ss);
26}
27
28int
29addbit(bitset ss, int ibit)
30{
31	int ibyte = BIT2BYTE(ibit);
32	BYTE mask = BIT2MASK(ibit);
33	
34	if (ss[ibyte] & mask)
35		return 0; /* Bit already set */
36	ss[ibyte] |= mask;
37	return 1;
38}
39
40#if 0 /* Now a macro */
41int
42testbit(bitset ss, int ibit)
43{
44	return (ss[BIT2BYTE(ibit)] & BIT2MASK(ibit)) != 0;
45}
46#endif
47
48int
49samebitset(bitset ss1, bitset ss2, int nbits)
50{
51	int i;
52	
53	for (i = NBYTES(nbits); --i >= 0; )
54		if (*ss1++ != *ss2++)
55			return 0;
56	return 1;
57}
58
59void
60mergebitset(bitset ss1, bitset ss2, int nbits)
61{
62	int i;
63	
64	for (i = NBYTES(nbits); --i >= 0; )
65		*ss1++ |= *ss2++;
66}