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) 2000-2016 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, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 /* Return: the address of the first occurence of chr in str or NULL
  21
  22    Inputs:
  23         in0:    str
  24         in1:    chr
  25
  26    A modified version of memchr.S, the search ends when the character is
  27    found or the terminating null character is encountered.
  28
  29    This implementation assumes little endian mode.  For big endian mode,
  30    the instruction czx1.r should be replaced by czx1.l.  */
  31
  32 #include <sysdep.h>
  33 #undef ret
  34
  35 #define saved_lc        r18
  36 #define poschr          r19
  37 #define pos0            r20
  38 #define val1            r21
  39 #define val2            r22
  40 #define tmp             r24
  41 #define chrx8           r25
  42 #define loopcnt         r30
  43
  44 #define str             in0
  45 #define chr             in1
  46
  47 ENTRY(strchr)
  48         .prologue
  49         alloc r2 = ar.pfs, 2, 0, 0, 0
  50         .save ar.lc, saved_lc
  51         mov     saved_lc = ar.lc        // save the loop counter
  52         .body
  53         mov     ret0 = str
  54         and     tmp = 7, str            // tmp = str % 8
  55         mux1    chrx8 = chr, @brcst
  56         extr.u  chr = chr, 0, 8         // retain only the last byte
  57         cmp.ne  p8, p0 = r0, r0         // clear p8
  58         ;;
  59         sub     loopcnt = 8, tmp        // loopcnt = 8 - tmp
  60         cmp.eq  p6, p0 = tmp, r0
  61 (p6)    br.cond.sptk    .str_aligned;;
  62         adds    loopcnt = -1, loopcnt;;
  63         mov     ar.lc = loopcnt
  64 .l1:
  65         ld1     val2 = [ret0], 1
  66         ;;
  67         cmp.eq  p6, p0 = val2, chr
  68         cmp.eq  p7, p0 = val2, r0
  69 (p6)    br.cond.spnt    .restore_and_exit
  70 (p7)    br.cond.spnt    .notfound
  71         br.cloop.sptk   .l1
  72 .str_aligned:
  73         ld8     val1 = [ret0], 8;;
  74         nop.b   0
  75         nop.b   0
  76 .l2:
  77         ld8.s   val2 = [ret0], 8        // don't bomb out here
  78         czx1.r  pos0 = val1
  79         xor     tmp = val1, chrx8       // if val1 contains chr, tmp will
  80         ;;                              // contain a zero in its position
  81         czx1.r  poschr = tmp
  82         cmp.ne  p6, p0 = 8, pos0
  83         ;;
  84         cmp.ne  p7, p0 = 8, poschr
  85 (p7)    br.cond.spnt .foundit
  86 (p6)    br.cond.spnt .notfound
  87         chk.s   val2, .recovery
  88 .back:
  89         mov     val1 = val2
  90         br.cond.dptk .l2
  91 .foundit:
  92 (p6)    cmp.lt  p8, p0 = pos0, poschr   // we found chr and null in the word
  93 (p8)    br.cond.spnt .notfound          // null was found before chr
  94         add     ret0 = ret0, poschr ;;
  95         adds    ret0 = -15, ret0 ;;     // should be -16, but we decrement
  96 .restore_and_exit:                      // ret0 in the next instruction
  97         adds    ret0 = -1, ret0         // ret0 was pointing 1 char too far
  98         mov     ar.lc = saved_lc        // restore the loop counter
  99         br.ret.sptk.many b0
 100 .notfound:
 101         mov     ret0 = r0               // return NULL if null was found
 102         mov     ar.lc = saved_lc
 103         br.ret.sptk.many b0
 104 .recovery:
 105         adds    ret0 = -8, ret0;;
 106         ld8     val2 = [ret0], 8        // bomb out here
 107         br.cond.sptk    .back
 108 END(strchr)
 109
 110 weak_alias (strchr, index)
 111 libc_hidden_builtin_def (strchr)