BSD 4_3_Net_1 release

[unix-history] / tn3270 / tn3270 / general / genbsubs.c

/*
* Copyright (c) 1988 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, Berkeley.  The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/

#ifndef lint
static char sccsid[] = "@(#)genbsubs.c  4.1 (Berkeley) 12/4/88";
#endif /* not lint */

/* The output of bunequal is the offset of the byte which didn't match;
* if all the bytes match, then we return n.
* bunequal(s1, s2, n) */

int
bunequal(s1, s2, n)
register char *s1, *s2;
register n;
{
   register int i = 0;

   while (i++ < n) {
       if (*s1++ != *s2++) {
           break;
       }
   }
   return(i-1);
}

/* bskip(s1, n, b) : finds the first occurrence of any byte != 'b' in the 'n'
* bytes beginning at 's1'.
*/

int
bskip(s1, n, b)
register char *s1;
register int n;
register int b;
{
   register int i = 0;

   while (i++ < n) {
       if (*s1++ != b) {
           break;
       }
   }
   return(i-1);
}

/*
* memNSchr(const void *s, int c, size_t n, int and)
*
* Like memchr, but the comparison is '((*s)&and) == c',
* and we increment our way through s by "stride" ('s += stride').
*
* We optimize for the most used strides of +1 and -1.
*/

unsigned char *
memNSchr(s, c, n, and, stride)
char *s;
int c;
unsigned int n;
int and;
int stride;
{
   register unsigned char _c, *_s, _and;

   _and = and;
   _c = (c&_and);
   _s = (unsigned char *)s;
   switch (stride) {
   case 1:
       while (n--) {
           if (((*_s)&_and) == _c) {
               return _s;
           }
           _s++;
       }
       break;
   case -1:
       while (n--) {
           if (((*_s)&_and) == _c) {
               return _s;
           }
           _s--;
       }
       break;
   default:
       while (n--) {
           if (((*_s)&_and) == _c) {
               return _s;
           }
           _s += stride;
       }
   }
   return 0;
}