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Annotation of 43BSD/lib/libc/vax/gen/strncat.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  "@(#)strncat.s  5.3 (Berkeley) 3/9/86"
                      9: #endif LIBC_SCCS
                     10: 
                     11: /*
                     12:  * Concatenate string s2 on the end of s1
                     13:  * and return the base of s1.  The parameter
                     14:  * n is the maximum length of string s2 to
                     15:  * concatenate.
                     16:  *
                     17:  * char *
                     18:  * strncat(s1, s2, n)
                     19:  *     char *s1, *s2;
                     20:  *     int n;
                     21:  */
                     22: #include "DEFS.h"
                     23: 
                     24: ENTRY(strncat, R6)
                     25:        movl    12(ap),r6       # r6 = n
                     26:        bleq    done            # n <= 0
                     27:        movl    4(ap),r3        # r3 = s1
                     28:        movl    r3,r1
                     29: 0:
                     30:        locc    $0,$65535,(r1)
                     31:        beql    0b
                     32:        movl    r1,r3           # r3 = index(s1, '\0');
                     33:        movl    8(ap),r1        # r1 = s2
                     34: 1:
                     35:        movzwl  $65535,r2       # r2 = bytes in first chunk
                     36:        cmpl    r6,r2           # r2 = min(bytes in chunk, n);
                     37:        jgeq    2f
                     38:        movl    r6,r2
                     39: 2:
                     40:        subl2   r2,r6           # update n
                     41:        locc    $0,r2,(r1)      # '\0' found?
                     42:        jneq    3f
                     43:        subl2   r2,r1           # back up pointer updated by locc
                     44:        movc3   r2,(r1),(r3)    # copy in next piece
                     45:        tstl    r6              # run out of space?
                     46:        jneq    1b
                     47:        clrb    (r3)            # force '\0' termination
                     48:        jbr     done
                     49: 3:
                     50:        subl2   r0,r2           # r2 = number of bytes to move
                     51:        subl2   r2,r1           # back up pointer updated by locc
                     52:        incl    r2              # copy '\0' as well
                     53:        movc3   r2,(r1),(r3)    # copy in last piece
                     54: done:
                     55:        movl    4(ap),r0        # return s1
                     56:        ret

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