2.11BSD#431 - /usr/src/lib/libc/pdp/gen/strcmp.s

   1: /*
   2:  * Copyright (c) 1987 Regents of the University of California.
   3:  * All rights reserved.  The Berkeley software License Agreement
   4:  * specifies the terms and conditions for redistribution.
   5:  */
   6: 
   7: #ifdef LIBC_SCCS
   8:         <@(#)strcmp.s	1.1 (Berkeley) 1/21/87\0>
   9:         .even
  10: #endif LIBC_SCCS
  11: 
  12: /*
  13:  * Compare string s1 lexicographically to string s2.
  14:  * Return:
  15:  *	0	s1 == s2
  16:  *	> 0	s1 > s2
  17:  *	< 0	s2 < s2
  18:  *
  19:  * strcmp(s1, s2)
  20:  *	char *s1, *s2;
  21:  */
  22: #include "DEFS.h"
  23: 
  24: ENTRY(strcmp)
  25:         mov     2(sp),r0        / r0 = s1
  26:         mov     4(sp),r1        / r1 = s2
  27: 1:
  28:         cmpb    (r0)+,(r1)      / compare the two strings
  29:         bne     2f              / stop on first mismatch
  30:         tstb    (r1)+           / but don't pass end of either string
  31:         bne     1b
  32:         clr     r0              / fell off end of strings with '\0' == '\0`
  33:         rts     pc              /   - success! return zero
  34: 2:
  35:         movb    -(r0),r0        / mismatch, return *s1 - *s2 ...
  36:         movb    (r1),r1         / (no subb instruction ...)
  37:         sub     r1,r0
  38:         rts     pc

Defined functions