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FROMLIST: lib/string.c: Add a macro for memchr_inv()

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We add a macro MEMCHR_MASK_GEN() so that both memchr_inv()
and memchr() can use it to generate a 8 bytes mask.

Signed-off-by: Yu-Jen Chang <arthurchang09@gmail.com>
Signed-off-by: Ching-Chun (Jim) Huang <jserv@ccns.ncku.edu.tw>
Change-Id: I2197b6455d321600a00043986f7c3a627e027d44
This commit is contained in:
Yu-Jen Chang 2022-07-10 22:28:21 +08:00 committed by spakkkk
parent 3cd48bb0af
commit 5d809acea5
1 changed files with 24 additions and 10 deletions
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34
lib/string.c
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@ -1020,6 +1020,29 @@ char *strnstr(const char *s1, const char *s2, size_t len)
EXPORT_SYMBOL(strnstr);
#endif
#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
#define MEMCHR_MASK_GEN(mask) (mask *= 0x0101010101010101ULL)
#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
#define MEMCHR_MASK_GEN(mask) \
do { \
mask *= 0x01010101; \
mask |= mask << 32; \
} while (0)
#else
#define MEMCHR_MASK_GEN(mask) \
do { \
mask |= mask << 8; \
mask |= mask << 16; \
mask |= mask << 32; \
} while (0)
#endif
#ifndef __HAVE_ARCH_MEMCHR
/**
* memchr - Find a character in an area of memory.
@ -1073,16 +1096,7 @@ void *memchr_inv(const void *start, int c, size_t bytes)
return check_bytes8(start, value, bytes);
value64 = value;
#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
value64 *= 0x0101010101010101ULL;
#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
value64 *= 0x01010101;
value64 |= value64 << 32;
#else
value64 |= value64 << 8;
value64 |= value64 << 16;
value64 |= value64 << 32;
#endif
MEMCHR_MASK_GEN(value64);
prefix = (unsigned long)start % 8;
if (prefix) {