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30 lines
999 B
C
30 lines
999 B
C
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#ifndef COSMOPOLITAN_LIBC_INTRIN_LOCKXCHG_H_
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#define COSMOPOLITAN_LIBC_INTRIN_LOCKXCHG_H_
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#if !(__ASSEMBLER__ + __LINKER__ + 0)
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COSMOPOLITAN_C_START_
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intptr_t lockxchg(void *, void *, size_t);
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#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
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/**
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* Exchanges *MEMORY into *LOCALVAR w/ one operation.
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*
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* @param MEMORY is uint𝑘_t[hasatleast 1] where 𝑘 ∈ {8,16,32,64}
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* @param LOCALVAR is uint𝑘_t[hasatleast 1]
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* @return LOCALVAR[0]
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* @see xchg()
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*/
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#define lockxchg(MEMORY, LOCALVAR) \
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({ \
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asm("xchg\t%0,%1" : "+%m"(*(MEMORY)), "+r"(*(LOCALVAR))); \
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*(LOCALVAR); \
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})
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#else
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#define lockxchg(MEM, VAR) \
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lockxchg(MEM, VAR, sizeof(*(MEM)) / (sizeof(*(MEM)) == sizeof(*(VAR))))
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#endif /* __GNUC__ && !__STRICT_ANSI__ */
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COSMOPOLITAN_C_END_
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#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
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#endif /* COSMOPOLITAN_LIBC_INTRIN_LOCKXCHG_H_ */
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