commands/elle/eebit.c

   1 /* ELLE - Copyright 1985, 1987 by Ken Harrenstien, SRI International
   2  *      This software is quasi-public; it may be used freely with
   3  *      like software, but may NOT be sold or made part of licensed
   4  *      products without permission of the author.
   5  */
   6 /*
   7  * EEBIT        Bit Array functions
   8  */
   9 #include "sb.h"
  10
  11 /* Char-bit array functions.   All assume that there are at least 8 bits
  12  * in a byte, and that the number of bytes per word is a power of 2.
  13  */
  14 /* CHBBITS represents log 2 of the # of bits stored per chbit-array word.
  15  *      WDBITS already has log2 of the # of bytes per word, and we are
  16  *      assuming each byte has at least 8 bits, so log2(8) = 3.
  17  */
  18 #define CHBSIZE (WDSIZE*8)      /* # bits per word */
  19 #define CHBBITS (WDBITS+3)      /* log2(CHBSIZE) */
  20 #define CHBMASK (CHBSIZE-1)
  21 #define CHBARYSIZ (128/CHBSIZE) /* # words per ASCII array */
  22
  23 /* CHBALLOC(size) - Allocates a char-bit array */
  24 int *
  25 chballoc(size)
  26 int size;
  27 {       return((int *)calloc((size + CHBSIZE-1)/CHBSIZE, (sizeof(int))));
  28 }
  29
  30 /* CHBIT(array, char) - Tests bit in char-bit array
  31  */
  32 chbit(array,c)
  33 register int *array, c;
  34 {       return(array[c >> CHBBITS] & (1 << (c & CHBMASK)));
  35 }
  36 /* CHBIS (array, char) - Sets bit in char-bit array
  37  */
  38 chbis(array,c)
  39 register int *array, c;
  40 {       array[c >> CHBBITS] |= (1 << (c & CHBMASK));
  41 }
  42 /* CHBIC (array, char) - Clears bit in char-bit array
  43  */
  44 chbic(array,c)
  45 register int *array, c;
  46 {       array[c >> CHBBITS] &= ~(1 << (c & CHBMASK));
  47 }