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- /*
- * Copyright 2008 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 SkFloatBits_DEFINED
- #define SkFloatBits_DEFINED
- #include "include/core/SkTypes.h"
- #include "include/private/SkSafe_math.h"
- #include <float.h>
- /** Convert a sign-bit int (i.e. float interpreted as int) into a 2s compliement
- int. This also converts -0 (0x80000000) to 0. Doing this to a float allows
- it to be compared using normal C operators (<, <=, etc.)
- */
- static inline int32_t SkSignBitTo2sCompliment(int32_t x) {
- if (x < 0) {
- x &= 0x7FFFFFFF;
- x = -x;
- }
- return x;
- }
- /** Convert a 2s compliment int to a sign-bit (i.e. int interpreted as float).
- This undoes the result of SkSignBitTo2sCompliment().
- */
- static inline int32_t Sk2sComplimentToSignBit(int32_t x) {
- int sign = x >> 31;
- // make x positive
- x = (x ^ sign) - sign;
- // set the sign bit as needed
- x |= SkLeftShift(sign, 31);
- return x;
- }
- union SkFloatIntUnion {
- float fFloat;
- int32_t fSignBitInt;
- };
- // Helper to see a float as its bit pattern (w/o aliasing warnings)
- static inline int32_t SkFloat2Bits(float x) {
- SkFloatIntUnion data;
- data.fFloat = x;
- return data.fSignBitInt;
- }
- // Helper to see a bit pattern as a float (w/o aliasing warnings)
- static inline float SkBits2Float(int32_t floatAsBits) {
- SkFloatIntUnion data;
- data.fSignBitInt = floatAsBits;
- return data.fFloat;
- }
- constexpr int32_t gFloatBits_exponent_mask = 0x7F800000;
- constexpr int32_t gFloatBits_matissa_mask = 0x007FFFFF;
- static inline bool SkFloatBits_IsFinite(int32_t bits) {
- return (bits & gFloatBits_exponent_mask) != gFloatBits_exponent_mask;
- }
- static inline bool SkFloatBits_IsInf(int32_t bits) {
- return ((bits & gFloatBits_exponent_mask) == gFloatBits_exponent_mask) &&
- (bits & gFloatBits_matissa_mask) == 0;
- }
- /** Return the float as a 2s compliment int. Just to be used to compare floats
- to each other or against positive float-bit-constants (like 0). This does
- not return the int equivalent of the float, just something cheaper for
- compares-only.
- */
- static inline int32_t SkFloatAs2sCompliment(float x) {
- return SkSignBitTo2sCompliment(SkFloat2Bits(x));
- }
- /** Return the 2s compliment int as a float. This undos the result of
- SkFloatAs2sCompliment
- */
- static inline float Sk2sComplimentAsFloat(int32_t x) {
- return SkBits2Float(Sk2sComplimentToSignBit(x));
- }
- // Scalar wrappers for float-bit routines
- #define SkScalarAs2sCompliment(x) SkFloatAs2sCompliment(x)
- #endif
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