IceFPU.h File Reference

Go to the source code of this file.

Macros
#define	AIR(x)   (IR(x) & 0x7fffffff)
	Absolute integer representation of a floating-point value. More...
#define	CHECK_VALID_FLOAT(x)   ASSERT(IsValidFloat(x));
#define	FR(x)   ((float&)(x))
	Floating-point representation of an integer value. More...
#define	IR(x)   ((udword&)(x))
	Integer representation of a floating-point value. More...
#define	IS_NEGATIVE_FLOAT(x)   (IR(x) & 0x80000000)
#define	SIGN_BITMASK   0x80000000
#define	SIR(x)   ((sdword&)(x))
	Signed integer representation of a floating-point value. More...

Enumerations
enum	FPUMode { FPU_FLOOR = 0, FPU_CEIL = 1, FPU_BEST = 2, FPU_FORCE_DWORD = 0x7fffffff }

Functions
inline_ float	ComputeFloatEpsilon ()
	This function computes the slowest possible floating-point value (you can also directly use FLT_EPSILON) More...
inline_ int	ConvertToSortable (float f)
inline_ float	FastFabs (float x)
inline_ float	fepsilon (float f)
	Returns the float ranged espilon value. More...
inline_ float	frsqrt (float f)
	Computes 1.0f / sqrtf(x). More...
inline_ float	fsat (float f)
	Saturates positive to zero. More...
inline_ float	fsqrt (float f)
	TO BE DOCUMENTED. More...
inline_ float	InvSqrt (const float &x)
	Computes 1.0f / sqrtf(x). Comes from NVIDIA. More...
inline_ bool	IsFloatZero (float x, float epsilon=1e-6f)
inline_ bool	IsIndeterminate (float value)
inline_ bool	IsMinusInf (float value)
inline_ bool	IsNAN (float value)
	Is the float valid ? More...
inline_ bool	IsPlusInf (float value)
inline_ bool	IsValidFloat (float value)
inline_ float	RSqrt (float number)

Detailed Description

Contains FPU related code.

Author

Pierre Terdiman

Date

April, 4, 2000

Definition in file IceFPU.h.

Macro Definition Documentation

#define AIR

(

x

)

(IR(x) & 0x7fffffff)

Absolute integer representation of a floating-point value.

Definition at line 24 of file IceFPU.h.

#define CHECK_VALID_FLOAT

(

x

)

ASSERT(IsValidFloat(x));

Definition at line 132 of file IceFPU.h.

#define FR

(

x

)

((float&)(x))

Floating-point representation of an integer value.

Definition at line 27 of file IceFPU.h.

Referenced by FastFabs().

#define IR

(

x

)

((udword&)(x))

Integer representation of a floating-point value.

Definition at line 18 of file IceFPU.h.

Referenced by FastFabs(), IsIndeterminate(), IsMinusInf(), IsNAN(), IsPlusInf(), rpcrawtodigi::EventRecords::mergeRecords(), SeedGeneratorFromRegionHitsEDProducer::produce(), PixelTracksProducer::produce(), and RPCPackingModule::rawData().

#define IS_NEGATIVE_FLOAT

(

x

)

(IR(x) & 0x80000000)

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.

Definition at line 31 of file IceFPU.h.

#define SIGN_BITMASK   0x80000000

Definition at line 15 of file IceFPU.h.

#define SIR

(

x

)

((sdword&)(x))

Signed integer representation of a floating-point value.

Definition at line 21 of file IceFPU.h.

Enumeration Type Documentation

enum FPUMode

Enumerator
FPU_FLOOR
FPU_CEIL
FPU_BEST
FPU_FORCE_DWORD

Definition at line 249 of file IceFPU.h.

             {
  FPU_FLOOR = 0,
  FPU_CEIL = 1,
  FPU_BEST = 2,

  FPU_FORCE_DWORD = 0x7fffffff
};

Function Documentation

inline_ float ComputeFloatEpsilon

(

)

This function computes the slowest possible floating-point value (you can also directly use FLT_EPSILON)

Definition at line 166 of file IceFPU.h.

References validate-o2o-wbm::f.

                                    {
  float f = 1.0f;
  ((udword&)f) ^= 1;
  return f - 1.0f;  // You can check it's the same as FLT_EPSILON
}

inline_ int ConvertToSortable

(

float

f

)

Definition at line 240 of file IceFPU.h.

                                       {
  int& Fi = (int&)f;
  int Fmask = (Fi >> 31);
  Fi ^= Fmask;
  Fmask &= ~(1 << 31);
  Fi -= Fmask;
  return Fi;
}

inline_ float FastFabs

(

float

x

)

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.

Definition at line 35 of file IceFPU.h.

References FR, and IR.

                                {
  udword FloatBits = IR(x) & 0x7fffffff;
  return FR(FloatBits);
}

inline_ float fepsilon

(

float

f

)

Returns the float ranged espilon value.

Definition at line 106 of file IceFPU.h.

References a, and b.

                                {
  udword b = (udword&)f & 0xff800000;
  udword a = b | 0x00000001;
  (float&)a -= (float&)b;
  // Result
  return (float&)a;
}

inline_ float frsqrt

(

float

f

)

Computes 1.0f / sqrtf(x).

Definition at line 63 of file IceFPU.h.

References x, and detailsBasic3DVector::y.

                              {
  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;
}

inline_ float fsat

(

float

f

)

Saturates positive to zero.

Definition at line 57 of file IceFPU.h.

References detailsBasic3DVector::y.

                            {
  udword y = (udword&)f & ~((sdword&)f >> 31);
  return (float&)y;
}

inline_ float fsqrt

(

float

f

)

TO BE DOCUMENTED.

Definition at line 97 of file IceFPU.h.

References detailsBasic3DVector::y.

                             {
  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;
}

inline_ float InvSqrt

(

const float &

x

)

Computes 1.0f / sqrtf(x). Comes from NVIDIA.

Definition at line 73 of file IceFPU.h.

References IEEE_1_0, createJobs::tmp, and detailsBasic3DVector::y.

                                      {
  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);
}

inline_ bool IsFloatZero	(	float	x,
		float	epsilon = 1e-6f
	)

Definition at line 172 of file IceFPU.h.

References geometryDiff::epsilon.

{ return x * x < epsilon; }

inline_ bool IsIndeterminate

(

float

value

)

Definition at line 116 of file IceFPU.h.

References IR.

Referenced by IsValidFloat().

{ return IR(value) == 0xffc00000; }

inline_ bool IsMinusInf

(

float

value

)

Definition at line 118 of file IceFPU.h.

References IR.

Referenced by IsValidFloat().

{ return IR(value) == 0xff800000; }

inline_ bool IsNAN

(

float

value

)

Is the float valid ?

Definition at line 115 of file IceFPU.h.

References IR.

Referenced by IsValidFloat().

{ return (IR(value) & 0x7f800000) == 0x7f800000; }

inline_ bool IsPlusInf

(

float

value

)

Definition at line 117 of file IceFPU.h.

References IR.

Referenced by IsValidFloat().

{ return IR(value) == 0x7f800000; }

inline_ bool IsValidFloat

(

float

value

)

Definition at line 120 of file IceFPU.h.

References IsIndeterminate(), IsMinusInf(), IsNAN(), and IsPlusInf().

                                       {
  if (IsNAN(value))
    return false;
  if (IsIndeterminate(value))
    return false;
  if (IsPlusInf(value))
    return false;
  if (IsMinusInf(value))
    return false;
  return true;
}

inline_ float RSqrt

(

float

number

)

Computes 1.0f / sqrtf(x). Comes from Quake3. Looks like the first one I had above. See http://www.magic-software.com/3DGEDInvSqrt.html

Definition at line 81 of file IceFPU.h.

References mps_fire::i, contentValuesFiles::number, and detailsBasic3DVector::y.

                                  {
  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;
}