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

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
        .asciz "@(#)index.s     5.6 (Berkeley) 6/1/90"
#endif /* LIBC_SCCS and 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