1 files changed, 90 insertions, 0 deletions
diff --git a/gfx/skia/skia/include/private/base/SkFloatBits.h b/gfx/skia/skia/include/private/base/SkFloatBits.h
new file mode 100644
index 0000000000..37a7b271ae
--- /dev/null
+++ b/gfx/skia/skia/include/private/base/SkFloatBits.h
@@ -0,0 +1,90 @@
+/*
+ * 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/private/base/SkMath.h"
+
+#include <cstdint>
+
+/** 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