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29 lines
1.3 KiB
C++
29 lines
1.3 KiB
C++
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#ifndef MEMCPY_H_
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#define MEMCPY_H_
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#if !(__ASSEMBLER__ + __LINKER__ + 0)
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/// Note: this header can be included only after libc++ headers.
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/// Note: you cannot write std::memcpy if you include this header.
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void *memcpy(void *, const void *, size_t);
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#ifdef __GNUC__
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#define __memcpy_isgoodsize(SIZE) \
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(__builtin_constant_p(SIZE) && ((SIZE) <= __BIGGEST_ALIGNMENT__ && \
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__builtin_popcountl((unsigned)(SIZE)) == 1))
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#define memcpy(DEST, SRC, SIZE) \
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(__memcpy_isgoodsize(SIZE) ? __builtin_memcpy(DEST, SRC, SIZE) : ({ \
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void *DeSt = (DEST); \
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const void *SrC = (SRC); \
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size_t SiZe = (SIZE); \
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asm("call\tMemCpy" \
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: "=m"(*(char(*)[SiZe])(DeSt)) \
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: "D"(DeSt), "S"(SrC), "d"(SiZe), "m"(*(const char(*)[SiZe])(SrC)) \
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: "xmm3", "xmm4", "rcx", "cc"); \
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DeSt; \
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}))
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#endif
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#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
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#endif /* MEMCPY_H_ */
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