diff options
Diffstat (limited to 'arch/arm64/lib/memchr.S')
| -rw-r--r-- | arch/arm64/lib/memchr.S | 70 |
1 files changed, 56 insertions, 14 deletions
diff --git a/arch/arm64/lib/memchr.S b/arch/arm64/lib/memchr.S index 48a3ab636e4f..37a9f2a4f7f4 100644 --- a/arch/arm64/lib/memchr.S +++ b/arch/arm64/lib/memchr.S @@ -1,9 +1,6 @@ /* SPDX-License-Identifier: GPL-2.0-only */ /* - * Based on arch/arm/lib/memchr.S - * - * Copyright (C) 1995-2000 Russell King - * Copyright (C) 2013 ARM Ltd. + * Copyright (C) 2021 Arm Ltd. */ #include <linux/linkage.h> @@ -19,16 +16,61 @@ * Returns: * x0 - address of first occurrence of 'c' or 0 */ -WEAK(memchr) - and w1, w1, #0xff -1: subs x2, x2, #1 - b.mi 2f - ldrb w3, [x0], #1 - cmp w3, w1 - b.ne 1b - sub x0, x0, #1 + +#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 -2: mov x0, #0 +L(not_found): + mov result, #0 ret -ENDPIPROC(memchr) +SYM_FUNC_END(__pi_memchr) +SYM_FUNC_ALIAS_WEAK(memchr, __pi_memchr) EXPORT_SYMBOL_NOKASAN(memchr) |