sysdeps/vax/strchr.s

   1 /*
   2  * Copyright (c) 1988 Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #if defined(LIBC_SCCS) && !defined(lint)
  35         .asciz "@(#)strchr.s    5.4 (Berkeley) 6/1/90"
  36 #endif /* LIBC_SCCS and not lint */
  37
  38 /*
  39  * Find the first occurrence of c in the string cp.
  40  * Return pointer to match or null pointer.
  41  *
  42  * char *
  43  * strchr(cp, c)
  44  *      char *cp, c;
  45  */
  46 #include "DEFS.h"
  47
  48         .lcomm  tbl,256
  49
  50 ENTRY(strchr, 0)
  51         movzwl  $65535,r4       /* handy constant */
  52         movq    4(ap),r1        /* r1 = cp; r2 = c */
  53         movzbl  r2,r2
  54         beql    Lzero           /* special case for c == '\0' */
  55
  56 /*
  57  * Fancy scanc version.  Alas, it is not reentrant.
  58  */
  59         movab   tbl,r3          /* r3 = base of table */
  60         bbss    $0,(r3),Lreent  /* ensure not reentering */
  61         movab   (r3)[r2],r5
  62         incb    (r5)            /* mark both '\0' and c */
  63 0:
  64         scanc   r4,(r1),(r3),$1 /* look for c or '\0' */
  65         beql    0b              /* still looking */
  66         movl    r1,r0           /* return whatever we found */
  67         tstb    (r0)
  68         bneq    1f              #       unless it was '\0':
  69         clrl    r0              #       then return NULL
  70 1:
  71         clrb    (r5)            /* clean up table */
  72         clrb    (r3)
  73         ret
  74
  75 /*
  76  * Special case for \0.
  77  */
  78 Lzero:
  79         locc    r2,r4,(r1)      /* just find end of string */
  80         beql    Lzero           /* still looking */
  81         movl    r1,r0           /* found it */
  82         ret
  83
  84 /*
  85  * Slower reentrant version is two two-step searches.  The first
  86  * phase runs until we know where the string ends; it locates the
  87  * first occurrence of c within a 65535-byte block.  If we find
  88  * the end of the string first, we switch to the second phase,
  89  * were we look only up to the known end of string.
  90  */
  91 Lreent:
  92 0:      /* first phase */
  93         movl    r1,r3
  94         locc    $0,r4,(r3)      /* look for '\0' */
  95         bneq    1f
  96         locc    r2,r4,(r3)      /* look for c */
  97         beql    0b              /* not found: reset pointer and loop */
  98         movl    r1,r0           /* found: return it */
  99         ret
 100 1:      /* second phase */
 101         subl3   r3,r1,r0        /* length of short block */
 102         locc    r2,r0,(r3)      /* look for c */
 103         beql    2f              /* not found: return NULL */
 104         movl    r1,r0
 105 2:      ret
 106
 107 weak_alias (strchr, index)