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///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
* Contains FPU related code.
* \file IceFPU.h
* \author Pierre Terdiman
* \date April, 4, 2000
*/
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Include Guard
#ifndef __ICEFPU_H__
#define __ICEFPU_H__
#include <algorithm>
#include <cmath>
#define SIGN_BITMASK 0x80000000
//! Integer representation of a floating-point value.
#define IR(x) ((udword&)(x))
//! Signed integer representation of a floating-point value.
#define SIR(x) ((sdword&)(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)&0x80000000)
//! Fast fabs for floating-point values. It just clears the sign bit.
//! Don't use it blindy, it can be faster or slower than the FPU comparison, depends on the context.
inline_ float FastFabs(float x)
{
udword FloatBits = IR(x)&0x7fffffff;
return FR(FloatBits);
}
//! Fast square root for floating-point values.
inline_ float FastSqrt(float square)
{
return std::sqrt(square);
}
//! Saturates positive to zero.
inline_ float fsat(float f)
{
udword y = (udword&)f & ~((sdword&)f >>31);
return (float&)y;
}
//! Computes 1.0f / sqrtf(x).
inline_ float frsqrt(float f)
{
float x = f * 0.5f;
udword y = 0x5f3759df - ((udword&)f >> 1);
// Iteration...
(float&)y = (float&)y * ( 1.5f - ( x * (float&)y * (float&)y ) );
// Result
return (float&)y;
}
//! Computes 1.0f / sqrtf(x). Comes from NVIDIA.
inline_ float InvSqrt(const float& x)
{
udword tmp = (udword(IEEE_1_0 << 1) + IEEE_1_0 - *(udword*)&x) >> 1;
float y = *(float*)&tmp;
return y * (1.47f - 0.47f * x * y * y);
}
//! Computes 1.0f / sqrtf(x). Comes from Quake3. Looks like the first one I had above.
//! See http://www.magic-software.com/3DGEDInvSqrt.html
inline_ float RSqrt(float number)
{
long i;
float x2, y;
const float threehalfs = 1.5f;
x2 = number * 0.5f;
y = number;
i = * (long *) &y;
i = 0x5f3759df - (i >> 1);
y = * (float *) &i;
y = y * (threehalfs - (x2 * y * y));
return y;
}
//! TO BE DOCUMENTED
inline_ float fsqrt(float f)
{
udword y = ( ( (sdword&)f - 0x3f800000 ) >> 1 ) + 0x3f800000;
// Iteration...?
// (float&)y = (3.0f - ((float&)y * (float&)y) / f) * (float&)y * 0.5f;
// Result
return (float&)y;
}
//! Returns the float ranged espilon value.
inline_ float fepsilon(float f)
{
udword b = (udword&)f & 0xff800000;
udword a = b | 0x00000001;
(float&)a -= (float&)b;
// Result
return (float&)a;
}
//! Is the float valid ?
inline_ bool IsNAN(float value) { return (IR(value)&0x7f800000) == 0x7f800000; }
inline_ bool IsIndeterminate(float value) { return IR(value) == 0xffc00000; }
inline_ bool IsPlusInf(float value) { return IR(value) == 0x7f800000; }
inline_ bool IsMinusInf(float value) { return IR(value) == 0xff800000; }
inline_ bool IsValidFloat(float value)
{
if(IsNAN(value)) return false;
if(IsIndeterminate(value)) return false;
if(IsPlusInf(value)) return false;
if(IsMinusInf(value)) return false;
return true;
}
#define CHECK_VALID_FLOAT(x) ASSERT(IsValidFloat(x));
/*
//! FPU precision setting function.
inline_ void SetFPU()
{
// This function evaluates whether the floating-point
// control word is set to single precision/round to nearest/
// exceptions disabled. If these conditions don't hold, the
// function changes the control word to set them and returns
// TRUE, putting the old control word value in the passback
// location pointed to by pwOldCW.
{
uword wTemp, wSave;
__asm fstcw wSave
if (wSave & 0x300 || // Not single mode
0x3f != (wSave & 0x3f) || // Exceptions enabled
wSave & 0xC00) // Not round to nearest mode
{
__asm
{
mov ax, wSave
and ax, not 300h ;; single mode
or ax, 3fh ;; disable all exceptions
and ax, not 0xC00 ;; round to nearest mode
mov wTemp, ax
fldcw wTemp
}
}
}
}
*/
//! This function computes the slowest possible floating-point value (you can also directly use FLT_EPSILON)
inline_ float ComputeFloatEpsilon()
{
float f = 1.0f;
((udword&)f)^=1;
return f - 1.0f; // You can check it's the same as FLT_EPSILON
}
inline_ bool IsFloatZero(float x, float epsilon=1e-6f)
{
return x*x < epsilon;
}
//! A global function to find MAX(a,b) using FCOMI/FCMOV
inline_ float FCMax2(float a, float b)
{
return std::max(a, b);
}
//! A global function to find MIN(a,b) using FCOMI/FCMOV
inline_ float FCMin2(float a, float b)
{
return std::min(a, b);
}
//! A global function to find MAX(a,b,c) using FCOMI/FCMOV
inline_ float FCMax3(float a, float b, float c)
{
return std::max(std::max(a, b), c);
}
//! A global function to find MIN(a,b,c) using FCOMI/FCMOV
inline_ float FCMin3(float a, float b, float c)
{
return std::min(std::min(a, b), c);
}
inline_ int ConvertToSortable(float f)
{
int& Fi = (int&)f;
int Fmask = (Fi>>31);
Fi ^= Fmask;
Fmask &= ~(1<<31);
Fi -= Fmask;
return Fi;
}
enum FPUMode
{
FPU_FLOOR = 0,
FPU_CEIL = 1,
FPU_BEST = 2,
FPU_FORCE_DWORD = 0x7fffffff
};
FUNCTION ICECORE_API FPUMode GetFPUMode();
FUNCTION ICECORE_API void SaveFPU();
FUNCTION ICECORE_API void RestoreFPU();
FUNCTION ICECORE_API void SetFPUFloorMode();
FUNCTION ICECORE_API void SetFPUCeilMode();
FUNCTION ICECORE_API void SetFPUBestMode();
FUNCTION ICECORE_API void SetFPUPrecision24();
FUNCTION ICECORE_API void SetFPUPrecision53();
FUNCTION ICECORE_API void SetFPUPrecision64();
FUNCTION ICECORE_API void SetFPURoundingChop();
FUNCTION ICECORE_API void SetFPURoundingUp();
FUNCTION ICECORE_API void SetFPURoundingDown();
FUNCTION ICECORE_API void SetFPURoundingNear();
FUNCTION ICECORE_API int intChop(const float& f);
FUNCTION ICECORE_API int intFloor(const float& f);
FUNCTION ICECORE_API int intCeil(const float& f);
#endif // __ICEFPU_H__
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