nvidia-texture-tools/src/nvmath/nvmath.h

// This code is in the public domain -- castanyo@yahoo.es

#pragma once
#ifndef NV_MATH_H
#define NV_MATH_H

#include <nvcore/nvcore.h>
#include <nvcore/Debug.h>

#include <math.h>
#include <limits.h> // INT_MAX

#if NV_OS_WIN32 || NV_OS_XBOX
#include <float.h>
#endif

// Function linkage
#if NVMATH_SHARED
#ifdef NVMATH_EXPORTS
#define NVMATH_API DLL_EXPORT
#define NVMATH_CLASS DLL_EXPORT_CLASS
#else
#define NVMATH_API DLL_IMPORT
#define NVMATH_CLASS DLL_IMPORT
#endif
#else // NVMATH_SHARED
#define NVMATH_API
#define NVMATH_CLASS
#endif // NVMATH_SHARED

#ifndef PI
#define PI                  float(3.1415926535897932384626433833)
#endif

#define NV_EPSILON          (0.0001f)
#define NV_NORMAL_EPSILON   (0.001f)

/*
#define SQ(r)               ((r)*(r))

#define SIGN_BITMASK        0x80000000

/// Integer representation of a floating-point value.
#define IR(x)               ((uint32 &)(x))

/// Absolute integer representation of a floating-point value
#define AIR(x)              (IR(x) & 0x7fffffff)

/// Floating-point representation of an integer value.
#define FR(x)               ((float&)(x))

/// Integer-based comparison of a floating point value.
/// Don't use it blindly, it can be faster or slower than the FPU comparison, depends on the context.
#define IS_NEGATIVE_FLOAT(x) (IR(x)&SIGN_BITMASK)
*/

inline double sqrt_assert(const double f)
{
    nvDebugCheck(f >= 0.0f);
    return sqrt(f);
}

inline float sqrtf_assert(const float f)
{
    nvDebugCheck(f >= 0.0f);
    return sqrtf(f);
}

inline double acos_assert(const double f)
{
    nvDebugCheck(f >= -1.0f && f <= 1.0f);
    return acos(f);
}

inline float acosf_assert(const float f)
{
    nvDebugCheck(f >= -1.0f && f <= 1.0f);
    return acosf(f);
}

inline double asin_assert(const double f)
{
    nvDebugCheck(f >= -1.0f && f <= 1.0f);
    return asin(f);
}

inline float asinf_assert(const float f)
{
    nvDebugCheck(f >= -1.0f && f <= 1.0f);
    return asinf(f);
}

// Replace default functions with asserting ones.
#define sqrt sqrt_assert
#define sqrtf sqrtf_assert
#define acos acos_assert
#define acosf acosf_assert
#define asin asin_assert
#define asinf asinf_assert


namespace nv
{
    inline float toRadian(float degree) { return degree * (PI / 180.0f); }
    inline float toDegree(float radian) { return radian * (180.0f / PI); }

    inline bool equal(const float f0, const float f1, const float epsilon = NV_EPSILON)
    {
        return fabs(f0-f1) <= epsilon;
    }

    inline bool isZero(const float f, const float epsilon = NV_EPSILON)
    {
        return fabs(f) <= epsilon;
    }

    inline bool isFinite(const float f)
    {
#if NV_OS_WIN32 || NV_OS_XBOX
        return _finite(f) != 0;
#elif NV_OS_DARWIN || NV_OS_FREEBSD
        return isfinite(f);
#elif NV_OS_LINUX
        return finitef(f);
#else
#   error "isFinite not supported"
#endif
        //return std::isfinite (f);
        //return finite (f);
    }

    inline bool isNan(const float f)
    {
#if NV_OS_WIN32 || NV_OS_XBOX
        return _isnan(f) != 0;
#elif NV_OS_DARWIN || NV_OS_FREEBSD
        return isnan(f);
#elif NV_OS_LINUX
        return isnanf(f);
#else
#   error "isNan not supported"
#endif
    }

    inline uint log2(uint i)
    {
        uint value = 0;
        while( i >>= 1 ) {
            value++;
        }
        return value;
    }

    inline float log2f(float x)
    {
        nvCheck(x >= 0);
        return logf(x) / logf(2.0f);
    }

    inline float lerp(float f0, float f1, float t)
    {
        const float s = 1.0f - t;
        return f0 * s + f1 * t;
    }

    inline float square(float f) { return f * f; }
    inline int square(int i) { return i * i; }

    inline float cube(float f) { return f * f; }
    inline int cube(int i) { return i * i; }

    // @@ Float to int conversions to be optimized at some point. See:
    // http://cbloomrants.blogspot.com/2009/01/01-17-09-float-to-int.html
    // http://www.stereopsis.com/sree/fpu2006.html
    // http://assemblyrequired.crashworks.org/2009/01/12/why-you-should-never-cast-floats-to-ints/
    // http://chrishecker.com/Miscellaneous_Technical_Articles#Floating_Point
    inline int iround(float f)
    {
        return int(f);
    }

    inline int ifloor(float f)
    {
        return int(floorf(f));
    }

    inline int iceil(float f)
    {
        return int(ceilf(f));
    }

	inline float frac(float f)
	{
		return f - floor(f);
	}

} // nv

#endif // NV_MATH_H