src/OpenGL ES 2.0/libGLESv2/mathutil.h

// SwiftShader Software Renderer
//
// Copyright(c) 2005-2012 TransGaming Inc.
//
// All rights reserved. No part of this software may be copied, distributed, transmitted,
// transcribed, stored in a retrieval system, translated into any human or computer
// language by any means, or disclosed to third parties without the explicit written
// agreement of TransGaming Inc. Without such an agreement, no rights or licenses, express
// or implied, including but not limited to any patent rights, are granted to you.
//

// mathutil.h: Math and bit manipulation functions.

#ifndef LIBGLESV2_MATHUTIL_H_
#define LIBGLESV2_MATHUTIL_H_

#include "common/debug.h"

#include <intrin.h>
#include <math.h>
#include <windows.h>

namespace gl
{
inline bool isPow2(int x)
{
    return (x & (x - 1)) == 0 && (x != 0);
}

inline int log2(int x)
{
    int r = 0;
    while((x >> r) > 1) r++;
    return r;
}

inline unsigned int ceilPow2(unsigned int x)
{
    if(x != 0) x--;
    x |= x >> 1;
    x |= x >> 2;
    x |= x >> 4;
    x |= x >> 8;
    x |= x >> 16;
    x++;

    return x;
}

template<typename T, typename MIN, typename MAX>
inline T clamp(T x, MIN min, MAX max)
{
    return x < min ? min : (x > max ? max : x);
}

inline float clamp01(float x)
{
    return clamp(x, 0.0f, 1.0f);
}

template<const int n>
inline unsigned int unorm(float x)
{
    const unsigned int max = 0xFFFFFFFF >> (32 - n);

    if(x > 1)
    {
        return max;
    }
    else if(x < 0)
    {
        return 0;
    }
    else
    {
        return (unsigned int)(max * x + 0.5f);
    }
}

inline bool supportsSSE2()
{
    static bool checked = false;
    static bool supports = false;

    if(checked)
    {
        return supports;
    }

    int info[4];
    __cpuid(info, 0);
    
    if(info[0] >= 1)
    {
        __cpuid(info, 1);

        supports = (info[3] >> 26) & 1;
    }

    checked = true;

    return supports;
}
}

#endif   // LIBGLESV2_MATHUTIL_H_