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Annotation of 43BSDTahoe/lib/libc/gen/gen.vax/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.
                      4:  *
                      5:  * Redistribution and use in source and binary forms are permitted
                      6:  * provided that the above copyright notice and this paragraph are
                      7:  * duplicated in all such forms and that any documentation,
                      8:  * advertising materials, and other materials related to such
                      9:  * distribution and use acknowledge that the software was developed
                     10:  * by the University of California, Berkeley.  The name of the
                     11:  * University may not be used to endorse or promote products derived
                     12:  * from this software without specific prior written permission.
                     13:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
                     14:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
                     15:  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
                     16:  */
                     17: 
                     18: #if defined(LIBC_SCCS) && !defined(lint)
                     19:        .asciz "@(#)strncat.s   5.5 (Berkeley) 6/27/88"
                     20: #endif /* LIBC_SCCS and not lint */
                     21: 
                     22: /*
                     23:  * Concatenate string s2 on the end of s1
                     24:  * and return the base of s1.  The parameter
                     25:  * n is the maximum length of string s2 to
                     26:  * concatenate.
                     27:  *
                     28:  * char *
                     29:  * strncat(s1, s2, n)
                     30:  *     char *s1, *s2;
                     31:  *     int n;
                     32:  */
                     33: #include "DEFS.h"
                     34: 
                     35: ENTRY(strncat, R6)
                     36:        movl    12(ap),r6       # r6 = n
                     37:        bleq    done            # n <= 0
                     38:        movl    4(ap),r3        # r3 = s1
                     39:        movl    r3,r1
                     40: 0:
                     41:        locc    $0,$65535,(r1)
                     42:        beql    0b
                     43:        movl    r1,r3           # r3 = index(s1, '\0');
                     44:        movl    8(ap),r1        # r1 = s2
                     45: 1:
                     46:        movzwl  $65535,r2       # r2 = bytes in first chunk
                     47:        cmpl    r6,r2           # r2 = min(bytes in chunk, n);
                     48:        jgeq    2f
                     49:        movl    r6,r2
                     50: 2:
                     51:        subl2   r2,r6           # update n
                     52:        locc    $0,r2,(r1)      # '\0' found?
                     53:        jneq    3f
                     54:        subl2   r2,r1           # back up pointer updated by locc
                     55:        movc3   r2,(r1),(r3)    # copy in next piece
                     56:        tstl    r6              # run out of space?
                     57:        jneq    1b
                     58:        clrb    (r3)            # force '\0' termination
                     59:        jbr     done
                     60: 3:
                     61:        subl2   r0,r2           # r2 = number of bytes to move
                     62:        subl2   r2,r1           # back up pointer updated by locc
                     63:        incl    r2              # copy '\0' as well
                     64:        movc3   r2,(r1),(r3)    # copy in last piece
                     65: done:
                     66:        movl    4(ap),r0        # return s1
                     67:        ret

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