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-rw-r--r--gfx/skia/skia/include/private/SkFloatBits.h91
1 files changed, 91 insertions, 0 deletions
diff --git a/gfx/skia/skia/include/private/SkFloatBits.h b/gfx/skia/skia/include/private/SkFloatBits.h
new file mode 100644
index 0000000000..89eea4b9e3
--- /dev/null
+++ b/gfx/skia/skia/include/private/SkFloatBits.h
@@ -0,0 +1,91 @@
+/*
+ * 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