1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/include/core/SkFloatBits.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,133 @@
1.4 +
1.5 +/*
1.6 + * Copyright 2008 The Android Open Source Project
1.7 + *
1.8 + * Use of this source code is governed by a BSD-style license that can be
1.9 + * found in the LICENSE file.
1.10 + */
1.11 +
1.12 +
1.13 +#ifndef SkFloatBits_DEFINED
1.14 +#define SkFloatBits_DEFINED
1.15 +
1.16 +#include "SkTypes.h"
1.17 +
1.18 +/** Convert a sign-bit int (i.e. float interpreted as int) into a 2s compliement
1.19 + int. This also converts -0 (0x80000000) to 0. Doing this to a float allows
1.20 + it to be compared using normal C operators (<, <=, etc.)
1.21 +*/
1.22 +static inline int32_t SkSignBitTo2sCompliment(int32_t x) {
1.23 + if (x < 0) {
1.24 + x &= 0x7FFFFFFF;
1.25 + x = -x;
1.26 + }
1.27 + return x;
1.28 +}
1.29 +
1.30 +/** Convert a 2s compliment int to a sign-bit (i.e. int interpreted as float).
1.31 + This undoes the result of SkSignBitTo2sCompliment().
1.32 + */
1.33 +static inline int32_t Sk2sComplimentToSignBit(int32_t x) {
1.34 + int sign = x >> 31;
1.35 + // make x positive
1.36 + x = (x ^ sign) - sign;
1.37 + // set the sign bit as needed
1.38 + x |= sign << 31;
1.39 + return x;
1.40 +}
1.41 +
1.42 +/** Given the bit representation of a float, return its value cast to an int.
1.43 + If the value is out of range, or NaN, return return +/- SK_MaxS32
1.44 +*/
1.45 +int32_t SkFloatBits_toIntCast(int32_t floatBits);
1.46 +
1.47 +/** Given the bit representation of a float, return its floor as an int.
1.48 + If the value is out of range, or NaN, return return +/- SK_MaxS32
1.49 + */
1.50 +SK_API int32_t SkFloatBits_toIntFloor(int32_t floatBits);
1.51 +
1.52 +/** Given the bit representation of a float, return it rounded to an int.
1.53 + If the value is out of range, or NaN, return return +/- SK_MaxS32
1.54 + */
1.55 +SK_API int32_t SkFloatBits_toIntRound(int32_t floatBits);
1.56 +
1.57 +/** Given the bit representation of a float, return its ceiling as an int.
1.58 + If the value is out of range, or NaN, return return +/- SK_MaxS32
1.59 + */
1.60 +SK_API int32_t SkFloatBits_toIntCeil(int32_t floatBits);
1.61 +
1.62 +
1.63 +union SkFloatIntUnion {
1.64 + float fFloat;
1.65 + int32_t fSignBitInt;
1.66 +};
1.67 +
1.68 +// Helper to see a float as its bit pattern (w/o aliasing warnings)
1.69 +static inline int32_t SkFloat2Bits(float x) {
1.70 + SkFloatIntUnion data;
1.71 + data.fFloat = x;
1.72 + return data.fSignBitInt;
1.73 +}
1.74 +
1.75 +// Helper to see a bit pattern as a float (w/o aliasing warnings)
1.76 +static inline float SkBits2Float(int32_t floatAsBits) {
1.77 + SkFloatIntUnion data;
1.78 + data.fSignBitInt = floatAsBits;
1.79 + return data.fFloat;
1.80 +}
1.81 +
1.82 +/** Return the float as a 2s compliment int. Just to be used to compare floats
1.83 + to each other or against positive float-bit-constants (like 0). This does
1.84 + not return the int equivalent of the float, just something cheaper for
1.85 + compares-only.
1.86 + */
1.87 +static inline int32_t SkFloatAs2sCompliment(float x) {
1.88 + return SkSignBitTo2sCompliment(SkFloat2Bits(x));
1.89 +}
1.90 +
1.91 +/** Return the 2s compliment int as a float. This undos the result of
1.92 + SkFloatAs2sCompliment
1.93 + */
1.94 +static inline float Sk2sComplimentAsFloat(int32_t x) {
1.95 + return SkBits2Float(Sk2sComplimentToSignBit(x));
1.96 +}
1.97 +
1.98 +/** Return x cast to a float (i.e. (float)x)
1.99 +*/
1.100 +float SkIntToFloatCast(int x);
1.101 +float SkIntToFloatCast_NoOverflowCheck(int x);
1.102 +
1.103 +/** Return the float cast to an int.
1.104 + If the value is out of range, or NaN, return +/- SK_MaxS32
1.105 +*/
1.106 +static inline int32_t SkFloatToIntCast(float x) {
1.107 + return SkFloatBits_toIntCast(SkFloat2Bits(x));
1.108 +}
1.109 +
1.110 +/** Return the floor of the float as an int.
1.111 + If the value is out of range, or NaN, return +/- SK_MaxS32
1.112 +*/
1.113 +static inline int32_t SkFloatToIntFloor(float x) {
1.114 + return SkFloatBits_toIntFloor(SkFloat2Bits(x));
1.115 +}
1.116 +
1.117 +/** Return the float rounded to an int.
1.118 + If the value is out of range, or NaN, return +/- SK_MaxS32
1.119 +*/
1.120 +static inline int32_t SkFloatToIntRound(float x) {
1.121 + return SkFloatBits_toIntRound(SkFloat2Bits(x));
1.122 +}
1.123 +
1.124 +/** Return the ceiling of the float as an int.
1.125 + If the value is out of range, or NaN, return +/- SK_MaxS32
1.126 +*/
1.127 +static inline int32_t SkFloatToIntCeil(float x) {
1.128 + return SkFloatBits_toIntCeil(SkFloat2Bits(x));
1.129 +}
1.130 +
1.131 +// Scalar wrappers for float-bit routines
1.132 +
1.133 +#define SkScalarAs2sCompliment(x) SkFloatAs2sCompliment(x)
1.134 +#define Sk2sComplimentAsScalar(x) Sk2sComplimentAsFloat(x)
1.135 +
1.136 +#endif
