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2 * Copyright 2011 Tilera Corporation. All Rights Reserved.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation, version 2.
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11 * NON INFRINGEMENT. See the GNU General Public License for
15 #include <linux/types.h>
16 #include <linux/string.h>
17 #include <linux/module.h>
18 #include "string-endian.h"
20 void *memchr(const void *s
, int c
, size_t n
)
22 const uint64_t *last_word_ptr
;
24 const char *last_byte_ptr
;
26 uint64_t goal
, before_mask
, v
, bits
;
29 if (__builtin_expect(n
== 0, 0)) {
30 /* Don't dereference any memory if the array is empty. */
34 /* Get an aligned pointer. */
35 s_int
= (uintptr_t) s
;
36 p
= (const uint64_t *)(s_int
& -8);
38 /* Create eight copies of the byte for which we are looking. */
41 /* Read the first word, but munge it so that bytes before the array
42 * will not match goal.
44 before_mask
= MASK(s_int
);
45 v
= (*p
| before_mask
) ^ (goal
& before_mask
);
47 /* Compute the address of the last byte. */
48 last_byte_ptr
= (const char *)s
+ n
- 1;
50 /* Compute the address of the word containing the last byte. */
51 last_word_ptr
= (const uint64_t *)((uintptr_t) last_byte_ptr
& -8);
53 while ((bits
= __insn_v1cmpeq(v
, goal
)) == 0) {
54 if (__builtin_expect(p
== last_word_ptr
, 0)) {
55 /* We already read the last word in the array,
63 /* We found a match, but it might be in a byte past the end
66 ret
= ((char *)p
) + (CFZ(bits
) >> 3);
67 return (ret
<= last_byte_ptr
) ? ret
: NULL
;
69 EXPORT_SYMBOL(memchr
);