skia WIPjarred/canvas

1 files changed, 54 insertions, 0 deletions

diff --git a/src/deps/skia/include/core/SkMath.h b/src/deps/skia/include/core/SkMath.h
new file mode 100644
index 000000000..97352afab
--- /dev/null
+++ b/src/deps/skia/include/core/SkMath.h
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2006 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 SkMath_DEFINED
+#define SkMath_DEFINED
+
+#include "include/core/SkTypes.h"
+
+// 64bit -> 32bit utilities
+
+// Handy util that can be passed two ints, and will automatically promote to
+// 64bits before the multiply, so the caller doesn't have to remember to cast
+// e.g. (int64_t)a * b;
+static inline int64_t sk_64_mul(int64_t a, int64_t b) {
+    return a * b;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+/**
+ *  Returns true if value is a power of 2. Does not explicitly check for
+ *  value <= 0.
+ */
+template <typename T> constexpr inline bool SkIsPow2(T value) {
+    return (value & (value - 1)) == 0;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+/**
+ *  Return a*b/((1 << shift) - 1), rounding any fractional bits.
+ *  Only valid if a and b are unsigned and <= 32767 and shift is > 0 and <= 8
+ */
+static inline unsigned SkMul16ShiftRound(U16CPU a, U16CPU b, int shift) {
+    SkASSERT(a <= 32767);
+    SkASSERT(b <= 32767);
+    SkASSERT(shift > 0 && shift <= 8);
+    unsigned prod = a*b + (1 << (shift - 1));
+    return (prod + (prod >> shift)) >> shift;
+}
+
+/**
+ *  Return a*b/255, rounding any fractional bits.
+ *  Only valid if a and b are unsigned and <= 32767.
+ */
+static inline U8CPU SkMulDiv255Round(U16CPU a, U16CPU b) {
+    return SkMul16ShiftRound(a,b,8);
+}
+
+#endif