CWE-ou-minkata/Sources/Plasma/NucleusLib/pnUtils/Private/pnUtMath.cpp

/*==LICENSE==*

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*==LICENSE==*/
/*****************************************************************************
*
*   $/Plasma20/Sources/Plasma/NucleusLib/pnUtils/Private/pnUtMath.cpp
*   
***/

#include "../Pch.h"
#pragma hdrstop


/*****************************************************************************
*
*   Exported bit manipulation functions
*
***/

//===========================================================================
#ifndef _M_IX86

unsigned MathHighBitPos (dword val) {
    ASSERT(val);
    double f = (double)val;
    return (*((dword *)&f + 1) >> 20) - 1023;
}

#else

__declspec(naked) unsigned __fastcall MathHighBitPos (dword) {
    __asm {
        bsr     eax, ecx
        ret     0
    };
}

#endif

//===========================================================================
#ifndef _M_IX86

unsigned MathLowBitPos (dword val) {
    val &= ~(val - 1);  // clear all but the low bit
    ASSERT(val);
    double f = (double)val;
    return (*((dword *)&f + 1) >> 20) - 1023;
}

#else

__declspec(naked) unsigned __fastcall MathLowBitPos (dword) {
    __asm {
        bsf     eax, ecx
        ret     0
    };
}

#endif