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Annotation of 43BSDReno/lib/libc/vax/string/index.s, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1980 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: (1) source distributions retain this entire copyright
        !             7:  * notice and comment, and (2) distributions including binaries display
        !             8:  * the following acknowledgement:  ``This product includes software
        !             9:  * developed by the University of California, Berkeley and its contributors''
        !            10:  * in the documentation or other materials provided with the distribution
        !            11:  * and in all advertising materials mentioning features or use of this
        !            12:  * software. Neither the name of the University nor the names of its
        !            13:  * contributors may be used to endorse or promote products derived
        !            14:  * from this software without specific prior written permission.
        !            15:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
        !            16:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
        !            17:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            18:  */
        !            19: 
        !            20: #if defined(LIBC_SCCS) && !defined(lint)
        !            21:        .asciz "@(#)index.s     5.6 (Berkeley) 6/1/90"
        !            22: #endif /* LIBC_SCCS and not lint */
        !            23: 
        !            24: /*
        !            25:  * Find the first occurence of c in the string cp.
        !            26:  * Return pointer to match or null pointer.
        !            27:  *
        !            28:  * char *
        !            29:  * index(cp, c)
        !            30:  *     char *cp, c;
        !            31:  */
        !            32: #include "DEFS.h"
        !            33: 
        !            34: ENTRY(index, 0)
        !            35:        movq    4(ap),r1        # r1 = cp; r2 = c
        !            36:        tstl    r2              # check for special case c == '\0'
        !            37:        bneq    2f
        !            38: 1:
        !            39:        locc    $0,$65535,(r1)  # just find end of string
        !            40:        beql    1b              # still looking
        !            41:        movl    r1,r0           # found it
        !            42:        ret
        !            43: 2:
        !            44:        moval   tbl,r3          # r3 = address of table
        !            45:        bbss    $0,(r3),5f      # insure not reentering
        !            46:        movab   (r3)[r2],r5     # table entry for c
        !            47:        incb    (r5)
        !            48:        movzwl  $65535,r4       # fast access
        !            49: 3:
        !            50:        scanc   r4,(r1),(r3),$1 # look for c or '\0'
        !            51:        beql    3b              # still looking
        !            52:        movl    r1,r0           # return pointer to char
        !            53:        tstb    (r0)            #    if have found '\0'
        !            54:        bneq    4f
        !            55:        clrl    r0              # else return 0
        !            56: 4:
        !            57:        clrb    (r5)            # clean up table
        !            58:        clrb    (r3)
        !            59:        ret
        !            60: 
        !            61:        .data
        !            62: tbl:   .space  256
        !            63:        .text
        !            64: 
        !            65: /*
        !            66:  * Reentrant, but slower version of index
        !            67:  */
        !            68: 5:
        !            69:        movl    r1,r3
        !            70: 6:
        !            71:        locc    $0,$65535,(r3)  # look for '\0'
        !            72:        bneq    7f
        !            73:        locc    r2,$65535,(r3)  # look for c
        !            74:        bneq    8f
        !            75:        movl    r1,r3           # reset pointer and ...
        !            76:        jbr     6b              # ... try again
        !            77: 7:
        !            78:        subl3   r3,r1,r4        # length of short block
        !            79:        incl    r4              # +1 for '\0'
        !            80:        locc    r2,r4,(r3)      # look for c
        !            81:        bneq    8f
        !            82:        ret
        !            83: 8:
        !            84:        movl    r1,r0           # return pointer to char
        !            85:        ret

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