fix asserts in SkMulDiv255Round, and add test
Review URL: https://codereview.chromium.org/13934010
git-svn-id: http://skia.googlecode.com/svn/trunk@8813 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests/MathTest.cpp b/tests/MathTest.cpp
index 105a3e4..372b41c 100644
--- a/tests/MathTest.cpp
+++ b/tests/MathTest.cpp
@@ -48,6 +48,32 @@
///////////////////////////////////////////////////////////////////////////////
+// test that SkMul16ShiftRound and SkMulDiv255Round return the same result
+static void test_muldivround(skiatest::Reporter* reporter) {
+#if 0
+ // this "complete" test is too slow, so we test a random sampling of it
+
+ for (int a = 0; a <= 32767; ++a) {
+ for (int b = 0; b <= 32767; ++b) {
+ unsigned prod0 = SkMul16ShiftRound(a, b, 8);
+ unsigned prod1 = SkMulDiv255Round(a, b);
+ SkASSERT(prod0 == prod1);
+ }
+ }
+#endif
+
+ SkRandom rand;
+ for (int i = 0; i < 10000; ++i) {
+ unsigned a = rand.nextU() & 0x7FFF;
+ unsigned b = rand.nextU() & 0x7FFF;
+
+ unsigned prod0 = SkMul16ShiftRound(a, b, 8);
+ unsigned prod1 = SkMulDiv255Round(a, b);
+
+ REPORTER_ASSERT(reporter, prod0 == prod1);
+ }
+}
+
static float float_blend(int src, int dst, float unit) {
return dst + (src - dst) * unit;
}
@@ -595,6 +621,8 @@
// disable for now
if (false) test_blend31(); // avoid bit rot, suppress warning
+
+ test_muldivround(reporter);
}
#include "TestClassDef.h"