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Annotation of 43BSD/lib/libc/vax/gen/strncmp.s, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Copyright (c) 1983 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:        .asciz  "@(#)strncmp.s  5.3 (Berkeley) 3/9/86"
                      9: #endif LIBC_SCCS
                     10: 
                     11: /*
                     12:  * Compare at most n characters of string
                     13:  * s1 lexicographically to string s2.
                     14:  * Return:
                     15:  *     0       s1 == s2
                     16:  *     > 0     s1 > s2
                     17:  *     < 0     s2 < s2
                     18:  *
                     19:  * strncmp(s1, s2, n)
                     20:  *     char *s1, *s2;
                     21:  *     int n;
                     22:  */
                     23: #include "DEFS.h"
                     24: 
                     25: ENTRY(strncmp, 0)
                     26:        movl    4(ap),r1        # r1 = s1
                     27:        movq    8(ap),r3        # r3 = s2; r4 = n
                     28: 1:
                     29:        clrl    r5              # calculate min bytes to next page boundry
                     30:        subb3   r1,$255,r5      # r5 = (bytes - 1) to end of page for s1
                     31:        subb3   r3,$255,r0      # r0 = (bytes - 1) to end of page for s2
                     32:        cmpb    r0,r5           # r5 = min(r0, r5);
                     33:        bgtru   2f
                     34:        movb    r0,r5
                     35: 2:
                     36:        incl    r5              # r5 = min bytes to next page boundry
                     37:        cmpl    r4,r5           # r5 = min(n, r5);
                     38:        bgeq    3f
                     39:        movl    r4,r5
                     40: 3:
                     41:        cmpc3   r5,(r1),(r3)    # compare strings
                     42:        bneq    4f
                     43:        subl2   r5,r4           # check for end of comparison
                     44:        beql    5f
                     45:        subl2   r5,r1           # check if found null yet
                     46:        locc    $0,r5,(r1)
                     47:        beql    1b              # not yet done, continue checking
                     48:        subl2   r0,r3
                     49:        mnegb   (r3),r0         # r0 = '\0' - *s2
                     50:        cvtbl   r0,r0
                     51:        ret
                     52: 4:
                     53:        subl2   r0,r5           # check for null in matching string
                     54:        subl2   r5,r1
                     55:        locc    $0,r5,(r1)
                     56:        bneq    5f
                     57:        subb3   (r3),(r1),r0    # r0 = *s1 - *s2
                     58:        cvtbl   r0,r0
                     59:        ret
                     60: 5:
                     61:        clrl    r0              # both the same to null
                     62:        ret

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