sysdeps/vax/strncmp.s

   1 /*
   2  * Copyright (c) 1983 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  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #if defined(LIBC_SCCS) && !defined(lint)
  31         .asciz "@(#)strncmp.s   5.6 (Berkeley) 6/1/90"
  32 #endif /* LIBC_SCCS and not lint */
  33
  34 /*
  35  * Compare at most n characters of string
  36  * s1 lexicographically to string s2.
  37  * Return:
  38  *      0       s1 == s2
  39  *      > 0     s1 > s2
  40  *      < 0     s2 < s2
  41  *
  42  * strncmp(s1, s2, n)
  43  *      char *s1, *s2;
  44  *      int n;
  45  */
  46 #include "DEFS.h"
  47
  48 ENTRY(strncmp, 0)
  49         movl    4(ap),r1        # r1 = s1
  50         movq    8(ap),r3        # r3 = s2; r4 = n
  51 1:
  52         clrl    r5              # calculate min bytes to next page boundary
  53         subb3   r1,$255,r5      # r5 = (bytes - 1) to end of page for s1
  54         subb3   r3,$255,r0      # r0 = (bytes - 1) to end of page for s2
  55         cmpb    r0,r5           # r5 = min(r0, r5);
  56         bgtru   2f
  57         movb    r0,r5
  58 2:
  59         incl    r5              # r5 = min bytes to next page boundary
  60         cmpl    r4,r5           # r5 = min(n, r5);
  61         bgeq    3f
  62         movl    r4,r5
  63 3:
  64         cmpc3   r5,(r1),(r3)    # compare strings
  65         bneq    4f
  66         subl2   r5,r4           # check for end of comparison
  67         beql    5f
  68         subl2   r5,r1           # check if found null yet
  69         locc    $0,r5,(r1)
  70         beql    1b              # not yet done, continue checking
  71         subl2   r0,r3
  72         mnegb   (r3),r0         # r0 = '\0' - *s2
  73         cvtbl   r0,r0
  74         ret
  75 4:
  76         subl2   r0,r5           # check for null in matching string
  77         subl2   r5,r1
  78         locc    $0,r5,(r1)
  79         bneq    5f
  80         subb3   (r3),(r1),r0    # r0 = *s1 - *s2
  81         cvtbl   r0,r0
  82         ret
  83 5:
  84         clrl    r0              # both the same to null
  85         ret