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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2021 Arm Ltd.
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
/*
* Find a character in an area of memory.
*
* Parameters:
* x0 - buf
* x1 - c
* x2 - n
* Returns:
* x0 - address of first occurrence of 'c' or 0
*/
#define L(label) .L ## label
#define REP8_01 0x0101010101010101
#define REP8_7f 0x7f7f7f7f7f7f7f7f
#define srcin x0
#define chrin w1
#define cntin x2
#define result x0
#define wordcnt x3
#define rep01 x4
#define repchr x5
#define cur_word x6
#define cur_byte w6
#define tmp x7
#define tmp2 x8
.p2align 4
nop
SYM_FUNC_START(__pi_memchr)
and chrin, chrin, #0xff
lsr wordcnt, cntin, #3
cbz wordcnt, L(byte_loop)
mov rep01, #REP8_01
mul repchr, x1, rep01
and cntin, cntin, #7
L(word_loop):
ldr cur_word, [srcin], #8
sub wordcnt, wordcnt, #1
eor cur_word, cur_word, repchr
sub tmp, cur_word, rep01
orr tmp2, cur_word, #REP8_7f
bics tmp, tmp, tmp2
b.ne L(found_word)
cbnz wordcnt, L(word_loop)
L(byte_loop):
cbz cntin, L(not_found)
ldrb cur_byte, [srcin], #1
sub cntin, cntin, #1
cmp cur_byte, chrin
b.ne L(byte_loop)
sub srcin, srcin, #1
ret
L(found_word):
CPU_LE( rev tmp, tmp)
clz tmp, tmp
sub tmp, tmp, #64
add result, srcin, tmp, asr #3
ret
L(not_found):
mov result, #0
ret
SYM_FUNC_END(__pi_memchr)
SYM_FUNC_ALIAS_WEAK(memchr, __pi_memchr)
EXPORT_SYMBOL_NOKASAN(memchr)
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