sysdeps/vax/memchr.s

   1 /*-
   2  * Copyright (c) 1990 The Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #if defined(LIBC_SCCS) && !defined(lint)
  35         .asciz "@(#)memchr.s    5.1 (Berkeley) 5/29/90"
  36 #endif /* LIBC_SCCS and not lint */
  37
  38 /*
  39  * Find the first occurrence of c in the memory at cp (length n).
  40  * Return pointer to match or null pointer.
  41  *
  42  * This code optimises the usual case (0 < n < 65535).
  43  *
  44  * void *
  45  * memchr(cp, c, n)
  46  *      char *cp, c;
  47  *      size_t n;
  48  */
  49
  50 #include "DEFS.h"
  51
  52 ENTRY(memchr, 0)
  53         movq    4(ap),r1        # r1 = cp; r2 = c
  54         movl    12(ap),r0       # r0 = n
  55         movzwl  $65535,r4       # handy constant
  56 0:
  57         cmpl    r0,r4           # check for annoying locc limit
  58         bgtru   3f
  59
  60         /* n <= 65535 */
  61         locc    r2,r0,(r1)      # search n bytes for c
  62         beql    2f              # done if not found (r0 already 0)
  63 1:      /* found character c at (r1) */
  64         movl    r1,r0
  65 2:
  66         ret
  67
  68 3:      /* n > 65535 */
  69         locc    r2,r4,(r1)      # search 65535 bytes for c
  70         beql    1b              # done if found
  71         decw    r0              # from 0 to 65535
  72         subl2   r0,r4           # adjust n
  73         brb     0b              # and loop