338 lines
9.2 KiB
C
338 lines
9.2 KiB
C
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///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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/**
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* Contains FPU related code.
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* \file IceFPU.h
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* \author Pierre Terdiman
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* \date April, 4, 2000
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*/
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///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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// Include Guard
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#ifndef __ICEFPU_H__
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#define __ICEFPU_H__
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#define SIGN_BITMASK 0x80000000
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//! Integer representation of a floating-point value.
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#define IR(x) ((udword&)(x))
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//! Signed integer representation of a floating-point value.
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#define SIR(x) ((sdword&)(x))
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//! Absolute integer representation of a floating-point value
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#define AIR(x) (IR(x)&0x7fffffff)
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//! Floating-point representation of an integer value.
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#define FR(x) ((float&)(x))
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//! Integer-based comparison of a floating point value.
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//! Don't use it blindly, it can be faster or slower than the FPU comparison, depends on the context.
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#define IS_NEGATIVE_FLOAT(x) (IR(x)&0x80000000)
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//! Fast fabs for floating-point values. It just clears the sign bit.
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//! Don't use it blindy, it can be faster or slower than the FPU comparison, depends on the context.
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inline_ float FastFabs(float x)
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{
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udword FloatBits = IR(x)&0x7fffffff;
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return FR(FloatBits);
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}
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//! Fast square root for floating-point values.
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inline_ float FastSqrt(float square)
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{
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#ifdef _MSC_VER
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float retval;
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__asm {
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mov eax, square
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sub eax, 0x3F800000
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sar eax, 1
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add eax, 0x3F800000
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mov [retval], eax
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}
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return retval;
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#else
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return sqrt(square);
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#endif
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}
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//! Saturates positive to zero.
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inline_ float fsat(float f)
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{
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udword y = (udword&)f & ~((sdword&)f >>31);
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return (float&)y;
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}
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//! Computes 1.0f / sqrtf(x).
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inline_ float frsqrt(float f)
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{
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float x = f * 0.5f;
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udword y = 0x5f3759df - ((udword&)f >> 1);
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// Iteration...
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(float&)y = (float&)y * ( 1.5f - ( x * (float&)y * (float&)y ) );
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// Result
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return (float&)y;
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}
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//! Computes 1.0f / sqrtf(x). Comes from NVIDIA.
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inline_ float InvSqrt(const float& x)
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{
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udword tmp = (udword(IEEE_1_0 << 1) + IEEE_1_0 - *(udword*)&x) >> 1;
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float y = *(float*)&tmp;
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return y * (1.47f - 0.47f * x * y * y);
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}
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//! Computes 1.0f / sqrtf(x). Comes from Quake3. Looks like the first one I had above.
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//! See http://www.magic-software.com/3DGEDInvSqrt.html
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inline_ float RSqrt(float number)
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{
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long i;
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float x2, y;
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const float threehalfs = 1.5f;
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x2 = number * 0.5f;
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y = number;
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i = * (long *) &y;
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i = 0x5f3759df - (i >> 1);
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y = * (float *) &i;
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y = y * (threehalfs - (x2 * y * y));
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return y;
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}
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//! TO BE DOCUMENTED
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inline_ float fsqrt(float f)
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{
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udword y = ( ( (sdword&)f - 0x3f800000 ) >> 1 ) + 0x3f800000;
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// Iteration...?
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// (float&)y = (3.0f - ((float&)y * (float&)y) / f) * (float&)y * 0.5f;
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// Result
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return (float&)y;
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}
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//! Returns the float ranged espilon value.
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inline_ float fepsilon(float f)
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{
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udword b = (udword&)f & 0xff800000;
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udword a = b | 0x00000001;
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(float&)a -= (float&)b;
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// Result
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return (float&)a;
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}
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//! Is the float valid ?
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inline_ bool IsNAN(float value) { return (IR(value)&0x7f800000) == 0x7f800000; }
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inline_ bool IsIndeterminate(float value) { return IR(value) == 0xffc00000; }
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inline_ bool IsPlusInf(float value) { return IR(value) == 0x7f800000; }
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inline_ bool IsMinusInf(float value) { return IR(value) == 0xff800000; }
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inline_ bool IsValidFloat(float value)
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{
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if(IsNAN(value)) return false;
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if(IsIndeterminate(value)) return false;
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if(IsPlusInf(value)) return false;
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if(IsMinusInf(value)) return false;
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return true;
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}
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#define CHECK_VALID_FLOAT(x) ASSERT(IsValidFloat(x));
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/*
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//! FPU precision setting function.
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inline_ void SetFPU()
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{
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// This function evaluates whether the floating-point
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// control word is set to single precision/round to nearest/
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// exceptions disabled. If these conditions don't hold, the
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// function changes the control word to set them and returns
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// TRUE, putting the old control word value in the passback
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// location pointed to by pwOldCW.
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{
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uword wTemp, wSave;
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__asm fstcw wSave
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if (wSave & 0x300 || // Not single mode
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0x3f != (wSave & 0x3f) || // Exceptions enabled
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wSave & 0xC00) // Not round to nearest mode
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{
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__asm
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{
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mov ax, wSave
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and ax, not 300h ;; single mode
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or ax, 3fh ;; disable all exceptions
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and ax, not 0xC00 ;; round to nearest mode
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mov wTemp, ax
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fldcw wTemp
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}
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}
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}
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}
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*/
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//! This function computes the slowest possible floating-point value (you can also directly use FLT_EPSILON)
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inline_ float ComputeFloatEpsilon()
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{
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float f = 1.0f;
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((udword&)f)^=1;
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return f - 1.0f; // You can check it's the same as FLT_EPSILON
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}
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inline_ bool IsFloatZero(float x, float epsilon=1e-6f)
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{
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return x*x < epsilon;
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}
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#define FCOMI_ST0 _asm _emit 0xdb _asm _emit 0xf0
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#define FCOMIP_ST0 _asm _emit 0xdf _asm _emit 0xf0
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#define FCMOVB_ST0 _asm _emit 0xda _asm _emit 0xc0
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#define FCMOVNB_ST0 _asm _emit 0xdb _asm _emit 0xc0
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#define FCOMI_ST1 _asm _emit 0xdb _asm _emit 0xf1
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#define FCOMIP_ST1 _asm _emit 0xdf _asm _emit 0xf1
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#define FCMOVB_ST1 _asm _emit 0xda _asm _emit 0xc1
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#define FCMOVNB_ST1 _asm _emit 0xdb _asm _emit 0xc1
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#define FCOMI_ST2 _asm _emit 0xdb _asm _emit 0xf2
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#define FCOMIP_ST2 _asm _emit 0xdf _asm _emit 0xf2
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#define FCMOVB_ST2 _asm _emit 0xda _asm _emit 0xc2
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#define FCMOVNB_ST2 _asm _emit 0xdb _asm _emit 0xc2
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#define FCOMI_ST3 _asm _emit 0xdb _asm _emit 0xf3
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#define FCOMIP_ST3 _asm _emit 0xdf _asm _emit 0xf3
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#define FCMOVB_ST3 _asm _emit 0xda _asm _emit 0xc3
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#define FCMOVNB_ST3 _asm _emit 0xdb _asm _emit 0xc3
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#define FCOMI_ST4 _asm _emit 0xdb _asm _emit 0xf4
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#define FCOMIP_ST4 _asm _emit 0xdf _asm _emit 0xf4
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#define FCMOVB_ST4 _asm _emit 0xda _asm _emit 0xc4
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#define FCMOVNB_ST4 _asm _emit 0xdb _asm _emit 0xc4
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#define FCOMI_ST5 _asm _emit 0xdb _asm _emit 0xf5
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#define FCOMIP_ST5 _asm _emit 0xdf _asm _emit 0xf5
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#define FCMOVB_ST5 _asm _emit 0xda _asm _emit 0xc5
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#define FCMOVNB_ST5 _asm _emit 0xdb _asm _emit 0xc5
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#define FCOMI_ST6 _asm _emit 0xdb _asm _emit 0xf6
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#define FCOMIP_ST6 _asm _emit 0xdf _asm _emit 0xf6
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#define FCMOVB_ST6 _asm _emit 0xda _asm _emit 0xc6
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#define FCMOVNB_ST6 _asm _emit 0xdb _asm _emit 0xc6
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#define FCOMI_ST7 _asm _emit 0xdb _asm _emit 0xf7
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#define FCOMIP_ST7 _asm _emit 0xdf _asm _emit 0xf7
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#define FCMOVB_ST7 _asm _emit 0xda _asm _emit 0xc7
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#define FCMOVNB_ST7 _asm _emit 0xdb _asm _emit 0xc7
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//! A global function to find MAX(a,b) using FCOMI/FCMOV
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inline_ float FCMax2(float a, float b)
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{
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#ifdef _MSC_VER
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float Res;
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_asm fld [a]
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_asm fld [b]
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FCOMI_ST1
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FCMOVB_ST1
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_asm fstp [Res]
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_asm fcomp
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return Res;
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#else
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return (a > b) ? a : b;
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#endif
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}
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//! A global function to find MIN(a,b) using FCOMI/FCMOV
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inline_ float FCMin2(float a, float b)
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{
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#ifdef _MSC_VER
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float Res;
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_asm fld [a]
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_asm fld [b]
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FCOMI_ST1
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FCMOVNB_ST1
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_asm fstp [Res]
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_asm fcomp
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return Res;
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#else
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return (a < b) ? a : b;
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#endif
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}
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//! A global function to find MAX(a,b,c) using FCOMI/FCMOV
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inline_ float FCMax3(float a, float b, float c)
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{
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#ifdef _MSC_VER
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float Res;
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_asm fld [a]
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_asm fld [b]
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_asm fld [c]
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FCOMI_ST1
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FCMOVB_ST1
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FCOMI_ST2
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FCMOVB_ST2
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_asm fstp [Res]
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_asm fcompp
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return Res;
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#else
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return (a > b) ? ((a > c) ? a : c) : ((b > c) ? b : c);
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#endif
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}
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//! A global function to find MIN(a,b,c) using FCOMI/FCMOV
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inline_ float FCMin3(float a, float b, float c)
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{
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#ifdef _MSC_VER
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float Res;
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_asm fld [a]
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_asm fld [b]
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_asm fld [c]
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FCOMI_ST1
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FCMOVNB_ST1
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FCOMI_ST2
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FCMOVNB_ST2
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_asm fstp [Res]
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_asm fcompp
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return Res;
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#else
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return (a < b) ? ((a < c) ? a : c) : ((b < c) ? b : c);
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#endif
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}
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inline_ int ConvertToSortable(float f)
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{
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int& Fi = (int&)f;
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int Fmask = (Fi>>31);
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Fi ^= Fmask;
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Fmask &= ~(1<<31);
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Fi -= Fmask;
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return Fi;
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}
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enum FPUMode
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{
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FPU_FLOOR = 0,
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FPU_CEIL = 1,
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FPU_BEST = 2,
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FPU_FORCE_DWORD = 0x7fffffff
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};
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FUNCTION ICECORE_API FPUMode GetFPUMode();
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FUNCTION ICECORE_API void SaveFPU();
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FUNCTION ICECORE_API void RestoreFPU();
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FUNCTION ICECORE_API void SetFPUFloorMode();
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FUNCTION ICECORE_API void SetFPUCeilMode();
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FUNCTION ICECORE_API void SetFPUBestMode();
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FUNCTION ICECORE_API void SetFPUPrecision24();
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FUNCTION ICECORE_API void SetFPUPrecision53();
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FUNCTION ICECORE_API void SetFPUPrecision64();
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FUNCTION ICECORE_API void SetFPURoundingChop();
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FUNCTION ICECORE_API void SetFPURoundingUp();
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FUNCTION ICECORE_API void SetFPURoundingDown();
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FUNCTION ICECORE_API void SetFPURoundingNear();
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FUNCTION ICECORE_API int intChop(const float& f);
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FUNCTION ICECORE_API int intFloor(const float& f);
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FUNCTION ICECORE_API int intCeil(const float& f);
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#endif // __ICEFPU_H__
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