usr/src/lib/libc/vax/string/index.s

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

#ifndef lint
static char sccsid[] = "@(#)index.s     5.1 (Berkeley) %G%";
#endif not lint

/*
 * Find the first occurence of c in the string cp.
 * Return pointer to match or null pointer.
 *
 * char *
 * index(cp, c)
 *      char *cp, c;
 */
#include "DEFS.h"

ENTRY(index, 0)
        movq    4(ap),r1        # r1 = cp; r2 = c
        tstl    r2              # check for special case c == '\0'
        bneq    2f
1:
        locc    $0,$65535,(r1)  # just find end of string
        beql    1b              # still looking
        movl    r1,r0           # found it
        ret
2:
        moval   tbl,r3          # r3 = address of table
        bbss    $0,(r3),5f      # insure not reentering
        movab   (r3)[r2],r5     # table entry for c
        incb    (r5)
        movzwl  $65535,r4       # fast access
3:
        scanc   r4,(r1),(r3),$1 # look for c or '\0'
        beql    3b              # still looking
        movl    r1,r0           # return pointer to char
        tstb    (r0)            #    if have found '\0'
        bneq    4f
        clrl    r0              # else return 0
4:
        clrb    (r5)            # clean up table
        clrb    (r3)
        ret

        .data
tbl:    .space  256
        .text

/*
 * Reentrant, but slower version of index
 */
5:
        movl    r1,r3
6:
        locc    $0,$65535,(r3)  # look for '\0'
        bneq    7f
        locc    r2,$65535,(r3)  # look for c
        bneq    8f
        movl    r1,r3           # reset pointer and ...
        jbr     6b              # ... try again
7:
        subl3   r3,r1,r4        # length of short block
        incl    r4              # +1 for '\0'
        locc    r2,r4,(r3)      # look for c
        bneq    8f
        ret
8:
        movl    r1,r0           # return pointer to char
        ret