citra/src/common/math_util.h

// Copyright 2013 Dolphin Emulator Project
// Licensed under GPLv2
// Refer to the license.txt file included.

#pragma once

#include "common/common.h"

#include <vector>

namespace MathUtil
{

static const u64 DOUBLE_SIGN = 0x8000000000000000ULL,
    DOUBLE_EXP  = 0x7FF0000000000000ULL,
    DOUBLE_FRAC = 0x000FFFFFFFFFFFFFULL,
    DOUBLE_ZERO = 0x0000000000000000ULL;

static const u32 FLOAT_SIGN = 0x80000000,
    FLOAT_EXP  = 0x7F800000,
    FLOAT_FRAC = 0x007FFFFF,
    FLOAT_ZERO = 0x00000000;

union IntDouble {
    double d;
    u64 i;
};
union IntFloat {
    float f;
    u32 i;
};

inline bool IsNAN(double d)
{
    IntDouble x; x.d = d;
    return ( ((x.i & DOUBLE_EXP) == DOUBLE_EXP) &&
             ((x.i & DOUBLE_FRAC) != DOUBLE_ZERO) );
}

inline bool IsQNAN(double d)
{
    IntDouble x; x.d = d;
    return ( ((x.i & DOUBLE_EXP) == DOUBLE_EXP) &&
             ((x.i & 0x0007fffffffffffULL) == 0x000000000000000ULL) &&
             ((x.i & 0x000800000000000ULL) == 0x000800000000000ULL) );
}

inline bool IsSNAN(double d)
{
    IntDouble x; x.d = d;
    return( ((x.i & DOUBLE_EXP) == DOUBLE_EXP) &&
            ((x.i & DOUBLE_FRAC) != DOUBLE_ZERO) &&
            ((x.i & 0x0008000000000000ULL) == DOUBLE_ZERO) );
}

inline float FlushToZero(float f)
{
    IntFloat x; x.f = f;
    if ((x.i & FLOAT_EXP) == 0)
        x.i &= FLOAT_SIGN;  // turn into signed zero
    return x.f;
}

inline double FlushToZeroAsFloat(double d)
{
    IntDouble x; x.d = d;
    if ((x.i & DOUBLE_EXP) < 0x3800000000000000ULL)
        x.i &= DOUBLE_SIGN;  // turn into signed zero
    return x.d;
}

enum PPCFpClass
{
    PPC_FPCLASS_QNAN = 0x11,
    PPC_FPCLASS_NINF = 0x9,
    PPC_FPCLASS_NN   = 0x8,
    PPC_FPCLASS_ND   = 0x18,
    PPC_FPCLASS_NZ   = 0x12,
    PPC_FPCLASS_PZ   = 0x2,
    PPC_FPCLASS_PD   = 0x14,
    PPC_FPCLASS_PN   = 0x4,
    PPC_FPCLASS_PINF = 0x5,
};

// Uses PowerPC conventions for the return value, so it can be easily
// used directly in CPU emulation.
u32 ClassifyDouble(double dvalue);
// More efficient float version.
u32 ClassifyFloat(float fvalue);

template<class T>
struct Rectangle
{
    T left;
    T top;
    T right;
    T bottom;

    Rectangle()
    { }

    Rectangle(T theLeft, T theTop, T theRight, T theBottom)
        : left(theLeft), top(theTop), right(theRight), bottom(theBottom)
    { }
    
    bool operator==(const Rectangle& r) { return left==r.left && top==r.top && right==r.right && bottom==r.bottom; }

    T GetWidth() const { return abs(right - left); }
    T GetHeight() const { return abs(bottom - top); }

    // If the rectangle is in a coordinate system with a lower-left origin, use
    // this Clamp.
    void ClampLL(T x1, T y1, T x2, T y2)
    {
        if (left < x1) left = x1;
        if (right > x2) right = x2;
        if (top > y1) top = y1;
        if (bottom < y2) bottom = y2;
    }

    // If the rectangle is in a coordinate system with an upper-left origin,
    // use this Clamp.
    void ClampUL(T x1, T y1, T x2, T y2) 
    {
        if (left < x1) left = x1;
        if (right > x2) right = x2;
        if (top < y1) top = y1;
        if (bottom > y2) bottom = y2;
    }
};

}  // namespace MathUtil

inline float pow2f(float x) {return x * x;}
inline double pow2(double x) {return x * x;}

float MathFloatVectorSum(const std::vector<float>&);

#define ROUND_UP(x, a)        (((x) + (a) - 1) & ~((a) - 1))
#define ROUND_DOWN(x, a)    ((x) & ~((a) - 1))

// Rounds down. 0 -> undefined
inline u64 Log2(u64 val)
{
#if defined(__GNUC__)
    return 63 - __builtin_clzll(val);

#elif defined(_MSC_VER) && defined(_M_X64)
    unsigned long result = -1;
    _BitScanReverse64(&result, val);
    return result;

#else
    u64 result = -1;
    while (val != 0)
    {
        val >>= 1;
        ++result;
    }
    return result;
#endif
}

// Tiny matrix/vector library.
// Used for things like Free-Look in the gfx backend.

class Matrix33
{
public:
    static void LoadIdentity(Matrix33 &mtx);

    // set mtx to be a rotation matrix around the x axis
    static void RotateX(Matrix33 &mtx, float rad);
    // set mtx to be a rotation matrix around the y axis
    static void RotateY(Matrix33 &mtx, float rad);

    // set result = a x b
    static void Multiply(const Matrix33 &a, const Matrix33 &b, Matrix33 &result);
    static void Multiply(const Matrix33 &a, const float vec[3], float result[3]);

    float data[9];
};

class Matrix44
{
public:
    static void LoadIdentity(Matrix44 &mtx);
    static void LoadMatrix33(Matrix44 &mtx, const Matrix33 &m33);
    static void Set(Matrix44 &mtx, const float mtxArray[16]);

    static void Translate(Matrix44 &mtx, const float vec[3]);

    static void Multiply(const Matrix44 &a, const Matrix44 &b, Matrix44 &result);

    float data[16];
};