SFloat.h

/*
 * Copyright 2006 The Android Open Source Project
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
#ifndef _SFloat_DEFINED_
#define _SFloat_DEFINED_
 
#include <stdint.h>
#include <math.h>
 
#define sk_float_sqrt(x)  sqrtf(x)
#define sk_float_sin(x)   sinf(x)
#define sk_float_cos(x)   cosf(x)
#define sk_float_tan(x)   tanf(x)
#define sk_float_floor(x) floorf(x)
#define sk_float_ceil(x)  ceilf(x)
#define sk_float_abs(x)   (float)::fabs(x)
 
#define sk_float_floor2int(x) (int)sk_float_floor(x)
#define sk_float_round2int(x) (int)sk_float_floor((x) + 0.5f)
#define sk_float_ceil2int(x)  (int)sk_float_ceil(x)
 
//#define sk_float_rsqrt(x)     sqrt(x)
//#define SK_SUPPORT_DEPRECATED_SCALARROUND
 
/** SK_Scalar1 is defined to be 1.0 represented as an float
 */
#define SK_Scalar1 (1.0f)
/** SK_Scalar1 is defined to be 1/2 represented as an float
 */
#define SK_ScalarHalf (0.5f)
/** SK_ScalarInfinity is defined to be infinity as an float
 */
#define SK_ScalarInfinity SK_FloatInfinity
/** SK_ScalarNegativeInfinity is defined to be negative infinity as an float
 */
#define SK_ScalarNegativeInfinity SK_FloatNegativeInfinity
/** SK_ScalarMax is defined to be the largest value representable as an float
 */
#define SK_ScalarMax (3.402823466e+38f)
/** SK_ScalarMin is defined to be the smallest value representable as an float
 */
#define SK_ScalarMin (-SK_ScalarMax)
/** SK_ScalarNaN is defined to be 'Not a Number' as an float
 */
#define SK_ScalarNaN SK_FloatNaN
 
/** SkIntToScalar(n) returns its integer argument as an float
 */
#define SkIntToScalar(n) ((float)(n))
/** SkFixedToScalar(n) returns its SkFixed argument as an float
 */
#define SkFixedToScalar(x) SkFixedToFloat(x)
/** SFloatToFixed(n) returns its float argument as an SkFixed
 */
#define SFloatToFixed(x) SkFloatToFixed(x)
 
#define SFloatToFloat(n) (n)
#ifndef SK_SCALAR_TO_FLOAT_EXCLUDED
#define SkFloatToScalar(n) (n)
#endif
 
#define SFloatToDouble(n)   (double)(n)
#define SkDoubleToScalar(n) (float)(n)
 
/** SFloatFraction(x) returns the signed fractional part of the argument
 */
#define SFloatFraction(x) sk_float_mod(x, 1.0f)
 
#define SFloatFloorToScalar(x) sk_float_floor(x)
#define SFloatCeilToScalar(x)  sk_float_ceil(x)
#define SFloatRoundToScalar(x) sk_float_floor((x) + 0.5f)
 
#define SFloatFloorToInt(x) sk_float_floor2int(x)
#define SFloatCeilToInt(x)  sk_float_ceil2int(x)
#define SFloatRoundToInt(x) sk_float_round2int(x)
#define SFloatTruncToInt(x) static_cast<int>(x)
 
#define SK_ANNOTATE_UNPROTECTED_READ(x)         (x)
#define SK_ANNOTATE_UNPROTECTED_WRITE(ptr, val) *(ptr) = (val)
 
/** Returns the absolute value of the specified float
 */
#define SFloatAbs(x) sk_float_abs(x)
/** Return x with the sign of y
 */
#define SFloatCopySign(x, y) sk_float_copysign(x, y)
/** Returns the product of two SFloats
 */
#define SFloatMul(a, b) ((float)(a) * (b))
/** Returns the product of two SFloats plus a third float
 */
#define SFloatMulAdd(a, b, c) ((float)(a) * (b) + (c))
/** Returns the quotient of two SFloats (a/b)
 */
#define SFloatDiv(a, b) ((float)(a) / (b))
/** Returns the mod of two SFloats (a mod b)
 */
#define SFloatMod(x, y) sk_float_mod(x, y)
/** Returns the product of the first two arguments, divided by the third argument
 */
#define SFloatMulDiv(a, b, c) ((float)(a) * (b) / (c))
/** Returns the multiplicative inverse of the float (1/x)
 */
#define SFloatInvert(x)     (SK_Scalar1 / (x))
#define SFloatFastInvert(x) (SK_Scalar1 / (x))
/** Returns the square root of the float
 */
#define SFloatSqrt(x) sk_float_sqrt(x)
/** Returns b to the e
 */
#define SFloatPow(b, e) sk_float_pow(b, e)
/** Returns the average of two SFloats (a+b)/2
 */
#define SFloatAve(a, b) (((a) + (b)) * 0.5f)
/** Returns one half of the specified float
 */
#define SFloatHalf(a) ((a)*0.5f)
 
#define SK_ScalarSqrt2      1.41421356f
#define SK_ScalarPI         3.14159265f
#define SK_ScalarTanPIOver8 0.414213562f
#define SK_ScalarRoot2Over2 0.707106781f
 
#define SkDegreesToRadians(degrees) ((degrees) * (SK_ScalarPI / 180))
#define SkRadiansToDegrees(radians) ((radians) * (180 / SK_ScalarPI))
#define SFloatSin(radians)          (float)sk_float_sin(radians)
#define SFloatCos(radians)          (float)sk_float_cos(radians)
#define SFloatTan(radians)          (float)sk_float_tan(radians)
#define SFloatASin(val)             (float)sk_float_asin(val)
#define SFloatACos(val)             (float)sk_float_acos(val)
#define SFloatATan2(y, x)           (float)sk_float_atan2(y, x)
#define SFloatExp(x)                (float)sk_float_exp(x)
#define SFloatLog(x)                (float)sk_float_log(x)
 
SNSBEGIN
/**
 *  Variant of SFloatRoundToInt, that performs the rounding step (adding 0.5) explicitly using
 *  double, to avoid possibly losing the low bit(s) of the answer before calling floor().
 *
 *  This routine will likely be slower than SFloatRoundToInt(), and should only be used when the
 *  extra precision is known to be valuable.
 *
 *  In particular, this catches the following case:
 *      float x = 0.49999997;
 *      int ix = SFloatRoundToInt(x);
 *      SASSERT(0 == ix);    // <--- fails
 *      ix = SkDScalarRoundToInt(x);
 *      SASSERT(0 == ix);    // <--- succeeds
 */
inline int SkDScalarRoundToInt(float x)
{
    double xx = x;
    xx += 0.5;
    return (int)floor(xx);
}
inline float SkMaxScalar(float a, float b)
{
    return a > b ? a : b;
}
inline float SkMinScalar(float a, float b)
{
    return a < b ? a : b;
}
 
/** SFloatIsNaN(n) returns true if argument is not a number
 */
inline bool SFloatIsNaN(float x)
{
    return x != x;
}
 
/** Returns true if x is not NaN and not infinite */
inline bool SFloatIsFinite(float x)
{
    // We rely on the following behavior of infinities and nans
    // 0 * finite --> 0
    // 0 * infinity --> NaN
    // 0 * NaN --> NaN
    float prod = x * 0;
    // At this point, prod will either be NaN or 0
    // Therefore we can return (prod == prod) or (0 == prod).
    return prod == prod;
}
 
/** Returns the value pinned between 0 and max inclusive
 */
inline float SFloatClampMax(float x, float max)
{
    return x < 0 ? 0 : x > max ? max : x;
}
/** Returns the value pinned between min and max inclusive
 */
inline float SFloatPin(float x, float min, float max)
{
    return x < min ? min : x > max ? max : x;
}
/** Returns the specified float squared (x*x)
 */
inline float SFloatSquare(float x)
{
    return x * x;
}
 
inline bool SFloatIsInt(float x)
{
    return x == (float)(int)x;
}
 
/**
 *  Returns -1 || 0 || 1 depending on the sign of value:
 *  -1 if x < 0
 *   0 if x == 0
 *   1 if x > 0
 */
inline int SFloatSignAsInt(float x)
{
    return x < 0 ? -1 : (x > 0);
}
 
// Scalar result version of above
inline float SFloatSignAsScalar(float x)
{
    return x < 0 ? -SK_Scalar1 : ((x > 0) ? SK_Scalar1 : 0);
}
 
#define SK_ScalarNearlyZero (SK_Scalar1 / (1 << 12))
 
inline bool SFloatNearlyZero(float x, float tolerance = SK_ScalarNearlyZero)
{
    SASSERT(tolerance >= 0);
    return SFloatAbs(x) <= tolerance;
}
 
inline bool SFloatNearlyEqual(float x, float y, float tolerance = SK_ScalarNearlyZero)
{
    SASSERT(tolerance >= 0);
    return SFloatAbs(x - y) <= tolerance;
}
 
/** Linearly interpolate between A and B, based on t.
    If t is 0, return A
    If t is 1, return B
    else interpolate.
    t must be [0..SK_Scalar1]
*/
inline float SFloatInterp(float A, float B, float t)
{
    SASSERT(t >= 0 && t <= SK_Scalar1);
    return A + (B - A) * t;
}
 
/*
 *  Helper to compare an array of scalars.
 */
inline bool SFloatsEqual(const float a[], const float b[], int n)
{
    SASSERT(n >= 0);
    for (int i = 0; i < n; ++i)
    {
        if (a[i] != b[i])
        {
            return false;
        }
    }
    return true;
}
 
SNSEND
#endif