SkFloatingPoint< RawType, ULPs > Class Template Reference

#include <SkFloatUtils.h>

Public Types
typedef SkTypeWithSize< sizeof(RawType) *CHAR_BIT >::UInt	Bits

Public Member Functions
	SkFloatingPoint (const RawType &x)
Bits	exponent_bits () const
Bits	fraction_bits () const
bool	is_nan () const
bool	AlmostEquals (const SkFloatingPoint &rhs) const

Static Public Attributes
static const size_t	kBitCount = CHAR_BIT * sizeof(RawType)
static const size_t	kFractionBitCount = SkNumericLimits<RawType>::digits - 1
static const size_t	kExponentBitCount = kBitCount - 1 - kFractionBitCount
static const Bits	kSignBitMask = static_cast<Bits>(1) << (kBitCount - 1)
static const Bits	kFractionBitMask
static const Bits	kExponentBitMask = ~(kSignBitMask | kFractionBitMask)
static const size_t	kMaxUlps = ULPs

Detailed Description

template<typename RawType, unsigned int ULPs>
class SkFloatingPoint< RawType, ULPs >

Definition at line 55 of file SkFloatUtils.h.

Member Typedef Documentation

Bits

template<typename RawType , unsigned int ULPs>

typedef SkTypeWithSize<sizeof(RawType)*CHAR_BIT>::UInt SkFloatingPoint< RawType, ULPs >::Bits

Bits is a unsigned integer the same size as the floating point number.

Definition at line 58 of file SkFloatUtils.h.

Constructor & Destructor Documentation

SkFloatingPoint()

template<typename RawType , unsigned int ULPs>

SkFloatingPoint< RawType, ULPs >::SkFloatingPoint ( const RawType &  x )

inlineexplicit

Constructs a FloatingPoint from a raw floating-point number.

On an Intel CPU, passing a non-normalized NAN (Not a Number) around may change its bits, although the new value is guaranteed to be also a NAN. Therefore, don't expect this constructor to preserve the bits in x when x is a NAN.

Definition at line 90 of file SkFloatUtils.h.

{ fU.value = x; }

Member Function Documentation

AlmostEquals()

template<typename RawType , unsigned int ULPs>

bool SkFloatingPoint< RawType, ULPs >::AlmostEquals ( const SkFloatingPoint< RawType, ULPs > &  rhs ) const

inline

Returns true iff this number is at most kMaxUlps ULP's away from ths. In particular, this function:

• returns false if either number is (or both are) NAN.
• treats really large numbers as almost equal to infinity.
• thinks +0.0 and -0.0 are 0 DLP's apart.

Definition at line 113 of file SkFloatUtils.h.

                                                        {
        // Any comparison operation involving a NAN must return false.
        if (is_nan() || rhs.is_nan()) return false;
 
        const Bits dist = DistanceBetweenSignAndMagnitudeNumbers(fU.bits,
                                                                 rhs.fU.bits);
        //SkDEBUGF("(%f, %f, %d) ", u_.value_, rhs.u_.value_, dist);
        return dist <= kMaxUlps;
    }

exponent_bits()

template<typename RawType , unsigned int ULPs>

Bits SkFloatingPoint< RawType, ULPs >::exponent_bits ( ) const

inline

Returns the exponent bits of this number.

Definition at line 93 of file SkFloatUtils.h.

{ return kExponentBitMask & fU.bits; }

fraction_bits()

template<typename RawType , unsigned int ULPs>

Bits SkFloatingPoint< RawType, ULPs >::fraction_bits ( ) const

inline

Returns the fraction bits of this number.

Definition at line 96 of file SkFloatUtils.h.

{ return kFractionBitMask & fU.bits; }

is_nan()

template<typename RawType , unsigned int ULPs>

bool SkFloatingPoint< RawType, ULPs >::is_nan ( ) const

inline

Returns true iff this is NAN (not a number).

Definition at line 99 of file SkFloatUtils.h.

                        {
        // It's a NAN if both of the folloowing are true:
        // * the exponent bits are all ones
        // * the fraction bits are not all zero.
        return (exponent_bits() == kExponentBitMask) && (fraction_bits() != 0);
    }

Member Data Documentation

kBitCount

template<typename RawType , unsigned int ULPs>

const size_t SkFloatingPoint< RawType, ULPs >::kBitCount = CHAR_BIT * sizeof(RawType)

static

of bits in a number.

Definition at line 61 of file SkFloatUtils.h.

kExponentBitCount

template<typename RawType , unsigned int ULPs>

const size_t SkFloatingPoint< RawType, ULPs >::kExponentBitCount = kBitCount - 1 - kFractionBitCount

static

of exponent bits in a number.

Definition at line 67 of file SkFloatUtils.h.

kExponentBitMask

template<typename RawType , unsigned int ULPs>

const Bits SkFloatingPoint< RawType, ULPs >::kExponentBitMask = ~(kSignBitMask | kFractionBitMask)

static

The mask for the exponent bits.

Definition at line 77 of file SkFloatUtils.h.

kFractionBitCount

template<typename RawType , unsigned int ULPs>

const size_t SkFloatingPoint< RawType, ULPs >::kFractionBitCount = SkNumericLimits<RawType>::digits - 1

static

of fraction bits in a number.

Definition at line 64 of file SkFloatUtils.h.

kFractionBitMask

template<typename RawType , unsigned int ULPs>

const Bits SkFloatingPoint< RawType, ULPs >::kFractionBitMask

static

Initial value:

=
        ~static_cast<Bits>(0) >> (kExponentBitCount + 1)

The mask for the fraction bits.

Definition at line 73 of file SkFloatUtils.h.

kMaxUlps

template<typename RawType , unsigned int ULPs>

const size_t SkFloatingPoint< RawType, ULPs >::kMaxUlps = ULPs

static

How many ULP's (Units in the Last Place) to tolerate when comparing.

Definition at line 80 of file SkFloatUtils.h.

kSignBitMask

template<typename RawType , unsigned int ULPs>

const Bits SkFloatingPoint< RawType, ULPs >::kSignBitMask = static_cast<Bits>(1) << (kBitCount - 1)

static

The mask for the sign bit.

Definition at line 70 of file SkFloatUtils.h.

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The documentation for this class was generated from the following file:

• third_party/skia/src/utils/SkFloatUtils.h