mirror of https://github.com/axmolengine/axmol.git
151 lines
4.5 KiB
C
151 lines
4.5 KiB
C
/*
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* Copyright (C) 2008 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef SkFloatBits_DEFINED
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#define SkFloatBits_DEFINED
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#include "SkTypes.h"
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/** Convert a sign-bit int (i.e. float interpreted as int) into a 2s compliement
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int. This also converts -0 (0x80000000) to 0. Doing this to a float allows
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it to be compared using normal C operators (<, <=, etc.)
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*/
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static inline int32_t SkSignBitTo2sCompliment(int32_t x) {
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if (x < 0) {
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x &= 0x7FFFFFFF;
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x = -x;
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}
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return x;
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}
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/** Convert a 2s compliment int to a sign-bit (i.e. int interpreted as float).
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This undoes the result of SkSignBitTo2sCompliment().
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*/
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static inline int32_t Sk2sComplimentToSignBit(int32_t x) {
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int sign = x >> 31;
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// make x positive
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x = (x ^ sign) - sign;
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// set the sign bit as needed
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x |= sign << 31;
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return x;
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}
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/** Given the bit representation of a float, return its value cast to an int.
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If the value is out of range, or NaN, return return +/- SK_MaxS32
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*/
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int32_t SkFloatBits_toIntCast(int32_t floatBits);
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/** Given the bit representation of a float, return its floor as an int.
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If the value is out of range, or NaN, return return +/- SK_MaxS32
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*/
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SK_API int32_t SkFloatBits_toIntFloor(int32_t floatBits);
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/** Given the bit representation of a float, return it rounded to an int.
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If the value is out of range, or NaN, return return +/- SK_MaxS32
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*/
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SK_API int32_t SkFloatBits_toIntRound(int32_t floatBits);
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/** Given the bit representation of a float, return its ceiling as an int.
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If the value is out of range, or NaN, return return +/- SK_MaxS32
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*/
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SK_API int32_t SkFloatBits_toIntCeil(int32_t floatBits);
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#ifdef SK_CAN_USE_FLOAT
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union SkFloatIntUnion {
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float fFloat;
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int32_t fSignBitInt;
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};
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// Helper to see a float as its bit pattern (w/o aliasing warnings)
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static inline int32_t SkFloat2Bits(float x) {
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SkFloatIntUnion data;
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data.fFloat = x;
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return data.fSignBitInt;
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}
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// Helper to see a bit pattern as a float (w/o aliasing warnings)
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static inline float SkBits2Float(int32_t floatAsBits) {
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SkFloatIntUnion data;
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data.fSignBitInt = floatAsBits;
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return data.fFloat;
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}
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/** Return the float as a 2s compliment int. Just to be used to compare floats
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to each other or against positive float-bit-constants (like 0). This does
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not return the int equivalent of the float, just something cheaper for
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compares-only.
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*/
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static inline int32_t SkFloatAs2sCompliment(float x) {
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return SkSignBitTo2sCompliment(SkFloat2Bits(x));
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}
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/** Return the 2s compliment int as a float. This undos the result of
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SkFloatAs2sCompliment
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*/
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static inline float Sk2sComplimentAsFloat(int32_t x) {
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return SkBits2Float(Sk2sComplimentToSignBit(x));
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}
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/** Return x cast to a float (i.e. (float)x)
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*/
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float SkIntToFloatCast(int x);
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float SkIntToFloatCast_NoOverflowCheck(int x);
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/** Return the float cast to an int.
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If the value is out of range, or NaN, return +/- SK_MaxS32
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*/
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static inline int32_t SkFloatToIntCast(float x) {
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return SkFloatBits_toIntCast(SkFloat2Bits(x));
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}
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/** Return the floor of the float as an int.
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If the value is out of range, or NaN, return +/- SK_MaxS32
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*/
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static inline int32_t SkFloatToIntFloor(float x) {
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return SkFloatBits_toIntFloor(SkFloat2Bits(x));
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}
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/** Return the float rounded to an int.
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If the value is out of range, or NaN, return +/- SK_MaxS32
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*/
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static inline int32_t SkFloatToIntRound(float x) {
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return SkFloatBits_toIntRound(SkFloat2Bits(x));
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}
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/** Return the ceiling of the float as an int.
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If the value is out of range, or NaN, return +/- SK_MaxS32
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*/
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static inline int32_t SkFloatToIntCeil(float x) {
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return SkFloatBits_toIntCeil(SkFloat2Bits(x));
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}
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#endif
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// Scalar wrappers for float-bit routines
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#ifdef SK_SCALAR_IS_FLOAT
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#define SkScalarAs2sCompliment(x) SkFloatAs2sCompliment(x)
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#define Sk2sComplimentAsScalar(x) Sk2sComplimentAsFloat(x)
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#else
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#define SkScalarAs2sCompliment(x) (x)
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#define Sk2sComplimentAsScalar(x) (x)
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#endif
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#endif
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