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26 lines
688 B
C
26 lines
688 B
C
#ifndef X86_CTZL_H
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#define X86_CTZL_H
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#include <intrin.h>
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#ifdef X86_CPUID
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# include "arch/x86/x86.h"
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#endif
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#if defined(_MSC_VER) && !defined(__clang__)
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/* This is not a general purpose replacement for __builtin_ctzl. The function expects that value is != 0
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* Because of that assumption trailing_zero is not initialized and the return value of _BitScanForward is not checked
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*/
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static __forceinline unsigned long __builtin_ctzl(unsigned long value) {
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#ifdef X86_CPUID
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x86_check_features();
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if (x86_cpu_has_tzcnt)
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return _tzcnt_u32(value);
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#endif
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unsigned long trailing_zero;
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_BitScanForward(&trailing_zero, value);
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return trailing_zero;
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}
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#endif
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#endif
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