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Annotation of 43BSDTahoe/lib/libc/gen/gen.vax/strncpy.s, revision 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 "@(#)strncpy.s   5.5 (Berkeley) 6/27/88"
        !            20: #endif /* LIBC_SCCS and not lint */
        !            21: 
        !            22: /*
        !            23:  * Copy string s2 over top of string s1.
        !            24:  * Truncate or null-pad to n bytes.
        !            25:  *
        !            26:  * char *
        !            27:  * strncpy(s1, s2, n)
        !            28:  *     char *s1, *s2;
        !            29:  */
        !            30: #include "DEFS.h"
        !            31: 
        !            32: ENTRY(strncpy, R6)
        !            33:        movl    12(ap),r6       # r6 = n
        !            34:        bleq    done            # n <= 0
        !            35:        movl    4(ap),r3        # r3 = s1
        !            36:        movl    8(ap),r1        # r1 = s2
        !            37: 1:
        !            38:        movzwl  $65535,r2       # r2 = bytes in first chunk
        !            39:        cmpl    r6,r2           # r2 = min(bytes in chunk, n);
        !            40:        jgeq    2f
        !            41:        movl    r6,r2
        !            42: 2:
        !            43:        subl2   r2,r6           # update n
        !            44:        locc    $0,r2,(r1)      # '\0' found?
        !            45:        jneq    3f
        !            46:        subl2   r2,r1           # back up pointer updated by locc
        !            47:        movc3   r2,(r1),(r3)    # copy in next piece
        !            48:        tstl    r6              # run out of space?
        !            49:        jneq    1b
        !            50:        jbr     done
        !            51: 3:                             # copy up to '\0' logic
        !            52:        addl2   r0,r6           # r6 = number of null-pad bytes
        !            53:        subl2   r0,r2           # r2 = number of bytes to move
        !            54:        subl2   r2,r1           # back up pointer updated by locc
        !            55:        movc3   r2,(r1),(r3)    # copy in last piece
        !            56: 4:                             # null-pad logic
        !            57:        movzwl  $65535,r2       # r2 = bytes in first chunk
        !            58:        cmpl    r6,r2           # r2 = min(bytes in chunk, n);
        !            59:        jgeq    5f
        !            60:        movl    r6,r2
        !            61: 5:
        !            62:        subl2   r2,r6           # update n
        !            63:        movc5   $0,(r3),$0,r2,(r3)# pad with '\0's
        !            64:        tstl    r6              # finished padding?
        !            65:        jneq    4b
        !            66: done:
        !            67:        movl    4(ap),r0        # return s1
        !            68:        ret

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