fix bug in computing return value from non-equal strings

[unix-history] / usr / src / lib / libc / vax / string / strcmp.s

/*      strcmp.s        4.4     84/12/02        */

/*
* Compare string s1 lexicographically to string s2.
* Return:
*      0       s1 == s2
*      > 0     s1 > s2
*      < 0     s2 < s2
*
* strcmp(s1, s2)
*      char *s1, *s2;
*/
#include "DEFS.h"

ENTRY(strcmp, 0)
       movl    4(ap),r1        # r1 = s1
       movl    8(ap),r3        # r3 = s2
1:
       cmpc3   $32,(r1),(r3)   # compare strings
       bneq    2f
       locc    $0,$32,-32(r1)  # check if contain null
       beql    1b
       subl2   r0,r3           # back up r3 to same point
       mnegb   (r3),r0         # r0 = '\0' - *s2
       cvtbl   r0,r0
       ret
2:
       subl3   r0,$32,r0       # check for null in matching string
       subl2   r0,r1
       locc    $0,r0,(r1)
       bneq    3f
       subb3   (r3),(r1),r0    # r0 = *s1 - *s2
       cvtbl   r0,r0
       ret
3:
       clrl    r0              # both the same to null
       ret