1 files changed, 66 insertions, 0 deletions
diff --git a/src/core/SkMathPriv.h b/src/core/SkMathPriv.h
index 1b64a6cd33..fca09f3ffc 100644
--- a/src/core/SkMathPriv.h
+++ b/src/core/SkMathPriv.h
@@ -92,4 +92,70 @@ static inline float SkPinToUnitFloat(float x) {
     static inline uint32_t SkBSwap32(uint32_t v) { return __builtin_bswap32(v); }
 #endif
 
+//! Returns the number of leading zero bits (0...32)
+int SkCLZ_portable(uint32_t);
+
+#ifndef SkCLZ
+    #if defined(SK_BUILD_FOR_WIN32)
+        #include <intrin.h>
+
+        static inline int SkCLZ(uint32_t mask) {
+            if (mask) {
+                unsigned long index;
+                _BitScanReverse(&index, mask);
+                // Suppress this bogus /analyze warning. The check for non-zero
+                // guarantees that _BitScanReverse will succeed.
+#pragma warning(suppress : 6102) // Using 'index' from failed function call
+                return index ^ 0x1F;
+            } else {
+                return 32;
+            }
+        }
+    #elif defined(SK_CPU_ARM32) || defined(__GNUC__) || defined(__clang__)
+        static inline int SkCLZ(uint32_t mask) {
+            // __builtin_clz(0) is undefined, so we have to detect that case.
+            return mask ? __builtin_clz(mask) : 32;
+        }
+    #else
+        #define SkCLZ(x)    SkCLZ_portable(x)
+    #endif
+#endif
+
+/**
+ *  Returns the smallest power-of-2 that is >= the specified value. If value
+ *  is already a power of 2, then it is returned unchanged. It is undefined
+ *  if value is <= 0.
+ */
+static inline int SkNextPow2(int value) {
+    SkASSERT(value > 0);
+    return 1 << (32 - SkCLZ(value - 1));
+}
+
+/**
+ *  Returns the log2 of the specified value, were that value to be rounded up
+ *  to the next power of 2. It is undefined to pass 0. Examples:
+ *  SkNextLog2(1) -> 0
+ *  SkNextLog2(2) -> 1
+ *  SkNextLog2(3) -> 2
+ *  SkNextLog2(4) -> 2
+ *  SkNextLog2(5) -> 3
+ */
+static inline int SkNextLog2(uint32_t value) {
+    SkASSERT(value != 0);
+    return 32 - SkCLZ(value - 1);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+/**
+ *  Return the next power of 2 >= n.
+ */
+static inline uint32_t GrNextPow2(uint32_t n) {
+    return n ? (1 << (32 - SkCLZ(n - 1))) : 1;
+}
+
+static inline int GrNextPow2(int n) {
+    SkASSERT(n >= 0); // this impl only works for non-neg.
+    return n ? (1 << (32 - SkCLZ(n - 1))) : 1;
+}
 #endif