minix/commands/elle/eebit.c
2009-11-09 10:26:00 +00:00

47 lines
1.4 KiB
C

/* ELLE - Copyright 1985, 1987 by Ken Harrenstien, SRI International
* This software is quasi-public; it may be used freely with
* like software, but may NOT be sold or made part of licensed
* products without permission of the author.
*/
/*
* EEBIT Bit Array functions
*/
#include "sb.h"
/* Char-bit array functions. All assume that there are at least 8 bits
* in a byte, and that the number of bytes per word is a power of 2.
*/
/* CHBBITS represents log 2 of the # of bits stored per chbit-array word.
* WDBITS already has log2 of the # of bytes per word, and we are
* assuming each byte has at least 8 bits, so log2(8) = 3.
*/
#define CHBSIZE (WDSIZE*8) /* # bits per word */
#define CHBBITS (WDBITS+3) /* log2(CHBSIZE) */
#define CHBMASK (CHBSIZE-1)
#define CHBARYSIZ (128/CHBSIZE) /* # words per ASCII array */
/* CHBALLOC(size) - Allocates a char-bit array */
int *
chballoc(size)
int size;
{ return((int *)calloc((size + CHBSIZE-1)/CHBSIZE, (sizeof(int))));
}
/* CHBIT(array, char) - Tests bit in char-bit array
*/
chbit(array,c)
register int *array, c;
{ return(array[c >> CHBBITS] & (1 << (c & CHBMASK)));
}
/* CHBIS (array, char) - Sets bit in char-bit array
*/
chbis(array,c)
register int *array, c;
{ array[c >> CHBBITS] |= (1 << (c & CHBMASK));
}
/* CHBIC (array, char) - Clears bit in char-bit array
*/
chbic(array,c)
register int *array, c;
{ array[c >> CHBBITS] &= ~(1 << (c & CHBMASK));
}