1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * Copyright (C) 2021 Arm Ltd.
4 */
5
6 #include <linux/linkage.h>
7 #include <asm/assembler.h>
8
9 /*
10 * Find a character in an area of memory.
11 *
12 * Parameters:
13 * x0 - buf
14 * x1 - c
15 * x2 - n
16 * Returns:
17 * x0 - address of first occurrence of 'c
18 */
19
20 #define L(label) .L ## label
21
22 #define REP8_01 0x0101010101010101
23 #define REP8_7f 0x7f7f7f7f7f7f7f7f
24
25 #define srcin x0
26 #define chrin w1
27 #define cntin x2
28
29 #define result x0
30
31 #define wordcnt x3
32 #define rep01 x4
33 #define repchr x5
34 #define cur_word x6
35 #define cur_byte w6
36 #define tmp x7
37 #define tmp2 x8
38
39 .p2align 4
40 nop
41 SYM_FUNC_START(__pi_memchr)
42 and chrin, chrin, #0xff
43 lsr wordcnt, cntin, #3
44 cbz wordcnt, L(byte_loop)
45 mov rep01, #REP8_01
46 mul repchr, x1, rep01
47 and cntin, cntin, #7
48 L(word_loop):
49 ldr cur_word, [srcin], #8
50 sub wordcnt, wordcnt, #1
51 eor cur_word, cur_word, repchr
52 sub tmp, cur_word, rep01
53 orr tmp2, cur_word, #REP8_7f
54 bics tmp, tmp, tmp2
55 b.ne L(found_word)
56 cbnz wordcnt, L(word_loop)
57 L(byte_loop):
58 cbz cntin, L(not_found)
59 ldrb cur_byte, [srcin], #1
60 sub cntin, cntin, #1
61 cmp cur_byte, chrin
62 b.ne L(byte_loop)
63 sub srcin, srcin, #1
64 ret
65 L(found_word):
66 CPU_LE( rev tmp, tmp)
67 clz tmp, tmp
68 sub tmp, tmp, #64
69 add result, srcin, tmp, asr #3
70 ret
71 L(not_found):
72 mov result, #0
73 ret
74 SYM_FUNC_END(__pi_memchr)
75 SYM_FUNC_ALIAS_WEAK(memchr, __pi_memchr)
76 EXPORT_SYMBOL_NOKASAN(memchr)
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