BitScanForward.hpp

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// Copyright (c) 2023 Sapphire's Suite. All Rights Reserved.
 
#pragma once
 
#ifndef SAPPHIRE_SUPPORT_BIT_SCAN_FORWARD_GUARD
#define SAPPHIRE_SUPPORT_BIT_SCAN_FORWARD_GUARD
 
#include <cstdint>
 
#include <SA/Support/Compilers.hpp>
 
#if SA_MSVC
 
    #include <intrin.h>
 
#endif
 
 
namespace SA
{
    inline uint32_t BitScanForward(uint32_t _mask)
    {
        if (!_mask)
            return ~uint32_t();
 
        unsigned long index = 0u;
 
#if SA_MSVC
 
        _BitScanForward64(&index, _mask);
#else
 
        // __builtin_ffs returns 1 + index if non zero.
        index = __builtin_ffs(_mask) - 1;
#endif
 
        return static_cast<uint32_t>(index);
    }
}
 
#endif // GUARD