sysdeps/ia64/strchr.S

   1 /* Optimized version of the standard strchr() function.
   2    This file is part of the GNU C Library.
   3    Copyright (C) 2000, 2001 Free Software Foundation, Inc.
   4    Contributed by Dan Pop <Dan.Pop@cern.ch>.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 /* Return: the address of the first occurence of chr in str or NULL
  22
  23    Inputs:
  24         in0:    str
  25         in1:    chr
  26
  27    A modified version of memchr.S, the search ends when the character is
  28    found or the terminating null character is encountered.
  29
  30    This implementation assumes little endian mode.  For big endian mode,
  31    the instruction czx1.r should be replaced by czx1.l.  */
  32
  33 #include <sysdep.h>
  34 #undef ret
  35
  36 #define saved_lc        r18
  37 #define poschr          r19
  38 #define pos0            r20
  39 #define val1            r21
  40 #define val2            r22
  41 #define tmp             r24
  42 #define chrx8           r25
  43 #define loopcnt         r30
  44
  45 #define str             in0
  46 #define chr             in1
  47
  48 ENTRY(strchr)
  49         .prologue
  50         alloc r2 = ar.pfs, 2, 0, 0, 0
  51         .save ar.lc, saved_lc
  52         mov     saved_lc = ar.lc        // save the loop counter
  53         .body
  54         mov     ret0 = str
  55         and     tmp = 7, str            // tmp = str % 8
  56         mux1    chrx8 = chr, @brcst
  57         extr.u  chr = chr, 0, 8         // retain only the last byte
  58         cmp.ne  p8, p0 = r0, r0         // clear p8
  59         ;;
  60         sub     loopcnt = 8, tmp        // loopcnt = 8 - tmp
  61         cmp.eq  p6, p0 = tmp, r0
  62 (p6)    br.cond.sptk    .str_aligned;;
  63         adds    loopcnt = -1, loopcnt;;
  64         mov     ar.lc = loopcnt
  65 .l1:
  66         ld1     val2 = [ret0], 1
  67         ;;
  68         cmp.eq  p6, p0 = val2, chr
  69         cmp.eq  p7, p0 = val2, r0
  70 (p6)    br.cond.spnt    .restore_and_exit
  71 (p7)    br.cond.spnt    .notfound
  72         br.cloop.sptk   .l1
  73 .str_aligned:
  74         ld8     val1 = [ret0], 8;;
  75         nop.b   0
  76         nop.b   0
  77 .l2:
  78         ld8.s   val2 = [ret0], 8        // don't bomb out here
  79         czx1.r  pos0 = val1
  80         xor     tmp = val1, chrx8       // if val1 contains chr, tmp will
  81         ;;                              // contain a zero in its position
  82         czx1.r  poschr = tmp
  83         cmp.ne  p6, p0 = 8, pos0
  84         ;;
  85         cmp.ne  p7, p0 = 8, poschr
  86 (p7)    br.cond.spnt .foundit
  87 (p6)    br.cond.spnt .notfound
  88         chk.s   val2, .recovery
  89 .back:
  90         mov     val1 = val2
  91         br.cond.dptk .l2
  92 .foundit:
  93 (p6)    cmp.lt  p8, p0 = pos0, poschr   // we found chr and null in the word
  94 (p8)    br.cond.spnt .notfound          // null was found before chr
  95         add     ret0 = ret0, poschr ;;
  96         adds    ret0 = -15, ret0 ;;     // should be -16, but we decrement
  97 .restore_and_exit:                      // ret0 in the next instruction
  98         adds    ret0 = -1, ret0         // ret0 was pointing 1 char too far
  99         mov     ar.lc = saved_lc        // restore the loop counter
 100         br.ret.sptk.many b0
 101 .notfound:
 102         mov     ret0 = r0               // return NULL if null was found
 103         mov     ar.lc = saved_lc
 104         br.ret.sptk.many b0
 105 .recovery:
 106         adds    ret0 = -8, ret0;;
 107         ld8     val2 = [ret0], 8        // bomb out here
 108         br.cond.sptk    .back
 109 END(strchr)
 110
 111 weak_alias(strchr, index)