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/* Optimized version of the standard strchr() function.
This file is part of the GNU C Library.
Copyright (C) 2000-2023 Free Software Foundation, Inc.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
/* Return: the address of the first occurence of chr in str or NULL
Inputs:
in0: str
in1: chr
A modified version of memchr.S, the search ends when the character is
found or the terminating null character is encountered.
This implementation assumes little endian mode. For big endian mode,
the instruction czx1.r should be replaced by czx1.l. */
#include <sysdep.h>
#undef ret
#define saved_lc r18
#define poschr r19
#define pos0 r20
#define val1 r21
#define val2 r22
#define tmp r24
#define chrx8 r25
#define loopcnt r30
#define str in0
#define chr in1
ENTRY(strchr)
.prologue
alloc r2 = ar.pfs, 2, 0, 0, 0
.save ar.lc, saved_lc
mov saved_lc = ar.lc // save the loop counter
.body
mov ret0 = str
and tmp = 7, str // tmp = str % 8
mux1 chrx8 = chr, @brcst
extr.u chr = chr, 0, 8 // retain only the last byte
cmp.ne p8, p0 = r0, r0 // clear p8
;;
sub loopcnt = 8, tmp // loopcnt = 8 - tmp
cmp.eq p6, p0 = tmp, r0
(p6) br.cond.sptk .str_aligned;;
adds loopcnt = -1, loopcnt;;
mov ar.lc = loopcnt
.l1:
ld1 val2 = [ret0], 1
;;
cmp.eq p6, p0 = val2, chr
cmp.eq p7, p0 = val2, r0
(p6) br.cond.spnt .restore_and_exit
(p7) br.cond.spnt .notfound
br.cloop.sptk .l1
.str_aligned:
ld8 val1 = [ret0], 8;;
nop.b 0
nop.b 0
.l2:
ld8.s val2 = [ret0], 8 // don't bomb out here
czx1.r pos0 = val1
xor tmp = val1, chrx8 // if val1 contains chr, tmp will
;; // contain a zero in its position
czx1.r poschr = tmp
cmp.ne p6, p0 = 8, pos0
;;
cmp.ne p7, p0 = 8, poschr
(p7) br.cond.spnt .foundit
(p6) br.cond.spnt .notfound
chk.s val2, .recovery
.back:
mov val1 = val2
br.cond.dptk .l2
.foundit:
(p6) cmp.lt p8, p0 = pos0, poschr // we found chr and null in the word
(p8) br.cond.spnt .notfound // null was found before chr
add ret0 = ret0, poschr ;;
adds ret0 = -15, ret0 ;; // should be -16, but we decrement
.restore_and_exit: // ret0 in the next instruction
adds ret0 = -1, ret0 // ret0 was pointing 1 char too far
mov ar.lc = saved_lc // restore the loop counter
br.ret.sptk.many b0
.notfound:
mov ret0 = r0 // return NULL if null was found
mov ar.lc = saved_lc
br.ret.sptk.many b0
.recovery:
adds ret0 = -8, ret0;;
ld8 val2 = [ret0], 8 // bomb out here
br.cond.sptk .back
END(strchr)
weak_alias (strchr, index)
libc_hidden_builtin_def (strchr)
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