skalibs

Mirror/fork of https://skarnet.org/software/skalibs/
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bitarray_clearsetn.c (654B)


      1 /* ISC license. */
      2 
      3 #include <skalibs/bitarray.h>
      4 
      5 void bitarray_clearsetn (unsigned char *s, size_t a, size_t b, int h)
      6 {
      7   if (!b) return ;
      8   b += a ;
      9   if ((a >> 3) == ((b-1) >> 3))
     10   {
     11     unsigned char mask = (1 << (a & 7)) - 1 ^ (1 << (1 + (b-1 & 7))) - 1 ;
     12     if (h) s[a>>3] |= mask ; else s[a>>3] &= ~mask ;
     13   }
     14   else
     15   {
     16     unsigned char mask = ~((1 << (a & 7)) - 1) ;
     17     size_t i = (a>>3) + 1 ;
     18     if (h) s[a>>3] |= mask ; else s[a>>3] &= ~mask ;
     19     mask = h ? 0xff : 0x00 ;
     20     for (; i < b>>3 ; i++) s[i] = mask ;
     21     if (b & 7)
     22     {
     23       mask = (1 << (b & 7)) - 1 ;
     24       if (h) s[b>>3] |= mask ; else s[b>>3] &= ~mask ;
     25     }
     26   }
     27 }