| 1 |
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| 2 | #ifndef _ASM_X86_SHARED_STRING_H
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| 3 | #define _ASM_X86_SHARED_STRING_H
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| 4 |
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| 5 | static __always_inline void *__inline_memcpy(void *to, const void *from, size_t len)
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| 6 | {
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| 7 | void *ret = to;
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| 8 |
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| 9 | asm volatile("rep movsb"
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| 10 | : "+D" (to), "+S" (from), "+c" (len)
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| 11 | : : "memory");
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| 12 | return ret;
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| 13 | }
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| 14 |
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| 15 | static __always_inline void *__inline_memset(void *s, int v, size_t n)
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| 16 | {
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| 17 | void *ret = s;
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| 18 |
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| 19 | asm volatile("rep stosb"
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| 20 | : "+D" (s), "+c" (n)
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| 21 | : "a" ((uint8_t)v)
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| 22 | : "memory");
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| 23 | return ret;
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| 24 | }
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| 25 |
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| 26 | |
| 27 | * Returns: 0 (equal)
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| 28 | * 1 (not equal)
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| 29 | *
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| 30 | * In contrast, the regular memcmp() follows glibc return value semantics.
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| 31 |
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| 32 | static __always_inline int __inline_memcmp(const void *s1, const void *s2, size_t len)
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| 33 | {
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| 34 | bool diff;
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| 35 |
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| 36 | |
| 37 | * Make sure ZF is properly set in the len==0 case because in it,
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| 38 | * RCX==0 and the REPE; CMPSB won't get executed.
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| 39 | *
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| 40 | * The "cc" clobber has no meaning anymore, just source compatibility.
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| 41 | * On x86 the flag status bits are automatically added to the clobber
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| 42 | * set when there are no =@ccXY constraints. Keep it as documentation.
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| 43 |
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| 44 | asm volatile("test %3, %3\n\t"
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| 45 | "repe cmpsb"
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| 46 | : "=@ccnz" (diff), "+D" (s1), "+S" (s2), "+c" (len)
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| 47 | : : "memory");
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| 48 |
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| 49 | return diff;
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| 50 | }
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| 51 |
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| 52 | #endif
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