summaryrefslogtreecommitdiffhomepage
path: root/third-party/Opcode/Ice/IceFPU.h
blob: 7d36aa43bb6791be6695f8e12fc3118207c6ab49 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
 *	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__