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32 lines
1.1 KiB
C
32 lines
1.1 KiB
C
#ifndef COSMOPOLITAN_LIBC_NEXGEN32E_FFS_H_
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#define COSMOPOLITAN_LIBC_NEXGEN32E_FFS_H_
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#if !(__ASSEMBLER__ + __LINKER__ + 0)
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COSMOPOLITAN_C_START_
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/*
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* BIT SCANNING 101
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* ctz(𝑥) 31^clz(𝑥) clz(𝑥)
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* uint32 𝑥 bsf(𝑥) tzcnt(𝑥) ffs(𝑥) bsr(𝑥) lzcnt(𝑥)
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* 0x00000000 wut 32 0 wut 32
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* 0x00000001 0 0 1 0 31
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* 0x80000001 0 0 1 31 0
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* 0x80000000 31 31 32 31 0
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* 0x00000010 4 4 5 4 27
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* 0x08000010 4 4 5 27 4
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* 0x08000000 27 27 28 27 4
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* 0xffffffff 0 0 1 31 0
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*/
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int ffs(int) pureconst;
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int ffsl(long) pureconst;
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int ffsll(long long) pureconst;
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#ifdef __GNUC__
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#define ffs(u) __builtin_ffs(u)
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#define ffsl(u) __builtin_ffsl(u)
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#define ffsll(u) __builtin_ffsll(u)
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#endif
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COSMOPOLITAN_C_END_
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#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
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#endif /* COSMOPOLITAN_LIBC_NEXGEN32E_FFS_H_ */
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