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

/*
 * Copyright (c) 1988 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that this notice is preserved and that due credit is given
 * to the University of California at Berkeley. The name of the University
 * may not be used to endorse or promote products derived from this
 * software without specific written prior permission. This software
 * is provided ``as is'' without express or implied warranty.
 */

#if defined(SYSLIBC_SCCS) && !defined(lint)
_sccsid:.asciz  "@(#)strchr.s   5.1 (Berkeley) %G%"
#endif /* SYSLIBC_SCCS and not lint */

#ifdef notdef
_sccsid:.asciz  "@(#)index.s    5.4 (Berkeley) 5/25/88"
#endif

/*
 * 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(strchr, 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