Parser/bitset.c

   1
   2 /* Bitset primitives used by the parser generator */
   3
   4 #include "pgenheaders.h"
   5 #include "bitset.h"
   6
   7 bitset
   8 newbitset(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
  22 void
  23 delbitset(bitset ss)
  24 {
  25         PyObject_FREE(ss);
  26 }
  27
  28 int
  29 addbit(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 */
  41 int
  42 testbit(bitset ss, int ibit)
  43 {
  44         return (ss[BIT2BYTE(ibit)] & BIT2MASK(ibit)) != 0;
  45 }
  46 #endif
  47
  48 int
  49 samebitset(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
  59 void
  60 mergebitset(bitset ss1, bitset ss2, int nbits)
  61 {
  62         int i;
  63
  64         for (i = NBYTES(nbits); --i >= 0; )
  65                 *ss1++ |= *ss2++;
  66 }