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113 lines
3.2 KiB
ArmAsm
113 lines
3.2 KiB
ArmAsm
/* Optimized version of the standard strchr() function.
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This file is part of the GNU C Library.
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Copyright (C) 2000, 2001, 2003 Free Software Foundation, Inc.
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Contributed by Dan Pop <Dan.Pop@cern.ch>.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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/* Return: the address of the first occurence of chr in str or NULL
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Inputs:
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in0: str
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in1: chr
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A modified version of memchr.S, the search ends when the character is
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found or the terminating null character is encountered.
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This implementation assumes little endian mode. For big endian mode,
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the instruction czx1.r should be replaced by czx1.l. */
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#include <sysdep.h>
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#undef ret
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#define saved_lc r18
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#define poschr r19
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#define pos0 r20
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#define val1 r21
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#define val2 r22
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#define tmp r24
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#define chrx8 r25
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#define loopcnt r30
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#define str in0
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#define chr in1
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ENTRY(strchr)
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.prologue
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alloc r2 = ar.pfs, 2, 0, 0, 0
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.save ar.lc, saved_lc
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mov saved_lc = ar.lc // save the loop counter
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.body
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mov ret0 = str
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and tmp = 7, str // tmp = str % 8
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mux1 chrx8 = chr, @brcst
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extr.u chr = chr, 0, 8 // retain only the last byte
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cmp.ne p8, p0 = r0, r0 // clear p8
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;;
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sub loopcnt = 8, tmp // loopcnt = 8 - tmp
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cmp.eq p6, p0 = tmp, r0
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(p6) br.cond.sptk .str_aligned;;
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adds loopcnt = -1, loopcnt;;
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mov ar.lc = loopcnt
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.l1:
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ld1 val2 = [ret0], 1
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;;
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cmp.eq p6, p0 = val2, chr
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cmp.eq p7, p0 = val2, r0
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(p6) br.cond.spnt .restore_and_exit
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(p7) br.cond.spnt .notfound
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br.cloop.sptk .l1
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.str_aligned:
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ld8 val1 = [ret0], 8;;
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nop.b 0
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nop.b 0
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.l2:
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ld8.s val2 = [ret0], 8 // don't bomb out here
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czx1.r pos0 = val1
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xor tmp = val1, chrx8 // if val1 contains chr, tmp will
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;; // contain a zero in its position
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czx1.r poschr = tmp
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cmp.ne p6, p0 = 8, pos0
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;;
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cmp.ne p7, p0 = 8, poschr
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(p7) br.cond.spnt .foundit
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(p6) br.cond.spnt .notfound
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chk.s val2, .recovery
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.back:
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mov val1 = val2
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br.cond.dptk .l2
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.foundit:
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(p6) cmp.lt p8, p0 = pos0, poschr // we found chr and null in the word
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(p8) br.cond.spnt .notfound // null was found before chr
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add ret0 = ret0, poschr ;;
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adds ret0 = -15, ret0 ;; // should be -16, but we decrement
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.restore_and_exit: // ret0 in the next instruction
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adds ret0 = -1, ret0 // ret0 was pointing 1 char too far
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mov ar.lc = saved_lc // restore the loop counter
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br.ret.sptk.many b0
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.notfound:
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mov ret0 = r0 // return NULL if null was found
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mov ar.lc = saved_lc
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br.ret.sptk.many b0
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.recovery:
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adds ret0 = -8, ret0;;
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ld8 val2 = [ret0], 8 // bomb out here
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br.cond.sptk .back
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END(strchr)
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weak_alias (strchr, index)
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libc_hidden_builtin_def (strchr)
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