fix asserts in SkMulDiv255Round, and add test
Review URL: https://codereview.chromium.org/13934010
git-svn-id: http://skia.googlecode.com/svn/trunk/include@8813 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/core/SkMath.h b/core/SkMath.h
index 314311f..cee3257 100644
--- a/core/SkMath.h
+++ b/core/SkMath.h
@@ -139,7 +139,7 @@
* 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(unsigned a, unsigned b, int shift) {
+static inline unsigned SkMul16ShiftRound(U16CPU a, U16CPU b, int shift) {
SkASSERT(a <= 32767);
SkASSERT(b <= 32767);
SkASSERT(shift > 0 && shift <= 8);
@@ -148,12 +148,12 @@
}
/**
- * Return a*b/255, rounding any fractional bits. Only valid if both
- * a and b are 0..255
+ * Return a*b/255, rounding any fractional bits.
+ * Only valid if a and b are unsigned and <= 32767.
*/
-static inline U8CPU SkMulDiv255Round(U8CPU a, U8CPU b) {
- SkASSERT((uint8_t)a == a);
- SkASSERT((uint8_t)b == b);
+static inline U8CPU SkMulDiv255Round(U16CPU a, U16CPU b) {
+ SkASSERT(a <= 32767);
+ SkASSERT(b <= 32767);
unsigned prod = SkMulS16(a, b) + 128;
return (prod + (prod >> 8)) >> 8;
}
