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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 "SkTypes.h"
#include "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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