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authorGravatar mtklein <mtklein@chromium.org>2016-05-27 10:47:31 -0700
committerGravatar Commit bot <commit-bot@chromium.org>2016-05-27 10:47:32 -0700
commit785a5b941a4d74a1f272729fe8dca55c6eda6bb8 (patch)
tree895897fb08b687abaac95e9be208272db32e4342 /tests
parent78d58d1084f0390c1c0f9123ac6e48efcd226f39 (diff)
Clean up SkFloatBits
- remove dead code - rewrite float -> int converters The strategy for the new converters is: - convert input to double - floor/ceil/round in double space - pin that double to [SK_MinS32, SK_MaxS32] - truncate that double to int32_t This simpler strategy does not work: - floor/ceil/round in float space - pin that float to [SK_MinS32, SK_MaxS32] - truncate that float to int32_t SK_MinS32 and SK_MaxS32 are not representable as floats: they round to the nearest float, ±2^31, which makes the pin insufficient for floats near SK_MinS32 (-2^31+1) or SK_MaxS32 (+2^31-1). float only has 24 bits of precision, and we need 31. double can represent all integers up to 50-something bits. An alternative is to pin in float to ±2147483520, the last exactly representable float before SK_MaxS32 (127 too small). Our tests test that we round as floor(x+0.5), which can return different numbers than round(x) for negative x. So this CL explicitly uses floor(x+0.5). I've updated the tests with ±inf and ±NaN, and tried to make them a little clearer, especially using SK_MinS32 instead of -SK_MaxS32. I have not timed anything here. I have never seen any of these methods in a profile. BUG=skia: GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2012333003 Review-Url: https://codereview.chromium.org/2012333003
Diffstat (limited to 'tests')
-rw-r--r--tests/MathTest.cpp42
1 files changed, 10 insertions, 32 deletions
diff --git a/tests/MathTest.cpp b/tests/MathTest.cpp
index ec1f936b9d..23785f742d 100644
--- a/tests/MathTest.cpp
+++ b/tests/MathTest.cpp
@@ -209,34 +209,29 @@ static float nextFloat(SkRandom& rand) {
/* returns true if a == b as resulting from (int)x. Since it is undefined
what to do if the float exceeds 2^32-1, we check for that explicitly.
*/
-static bool equal_float_native_skia(float x, uint32_t ni, uint32_t si) {
- if (!(x == x)) { // NAN
- return ((int32_t)si) == SK_MaxS32 || ((int32_t)si) == SK_MinS32;
+static bool equal_float_native_skia(float x, int32_t ni, int32_t si) {
+ // When the float is out of integer range (NaN, above, below),
+ // the C cast is undefined, but Skia's methods should have clamped.
+ if (!(x == x)) { // NaN
+ return si == SK_MaxS32 || si == SK_MinS32;
}
- // for out of range, C is undefined, but skia always should return NaN32
if (x > SK_MaxS32) {
- return ((int32_t)si) == SK_MaxS32;
+ return si == SK_MaxS32;
}
- if (x < -SK_MaxS32) {
- return ((int32_t)si) == SK_MinS32;
+ if (x < SK_MinS32) {
+ return si == SK_MinS32;
}
return si == ni;
}
static void assert_float_equal(skiatest::Reporter* reporter, const char op[],
- float x, uint32_t ni, uint32_t si) {
+ float x, int32_t ni, int32_t si) {
if (!equal_float_native_skia(x, ni, si)) {
ERRORF(reporter, "%s float %g bits %x native %x skia %x\n",
op, x, SkFloat2Bits(x), ni, si);
}
}
-static void test_float_cast(skiatest::Reporter* reporter, float x) {
- int ix = (int)x;
- int iix = SkFloatToIntCast(x);
- assert_float_equal(reporter, "cast", x, ix, iix);
-}
-
static void test_float_floor(skiatest::Reporter* reporter, float x) {
int ix = (int)floor(x);
int iix = SkFloatToIntFloor(x);
@@ -257,23 +252,17 @@ static void test_float_ceil(skiatest::Reporter* reporter, float x) {
}
static void test_float_conversions(skiatest::Reporter* reporter, float x) {
- test_float_cast(reporter, x);
test_float_floor(reporter, x);
test_float_round(reporter, x);
test_float_ceil(reporter, x);
}
-static void test_int2float(skiatest::Reporter* reporter, int ival) {
- float x0 = (float)ival;
- float x1 = SkIntToFloatCast(ival);
- REPORTER_ASSERT(reporter, x0 == x1);
-}
-
static void unittest_fastfloat(skiatest::Reporter* reporter) {
SkRandom rand;
size_t i;
static const float gFloats[] = {
+ 0.f/0.f, -0.f/0.f, 1.f/0.f, -1.f/0.f,
0.f, 1.f, 0.5f, 0.499999f, 0.5000001f, 1.f/3,
0.000000001f, 1000000000.f, // doesn't overflow
0.0000000001f, 10000000000.f // does overflow
@@ -289,17 +278,6 @@ static void unittest_fastfloat(skiatest::Reporter* reporter) {
float x = nextFloat(rand);
test_float_conversions(reporter, x);
}
-
- test_int2float(reporter, 0);
- test_int2float(reporter, 1);
- test_int2float(reporter, -1);
- for (i = 0; i < 100000; i++) {
- // for now only test ints that are 24bits or less, since we don't
- // round (down) large ints the same as IEEE...
- int ival = rand.nextU() & 0xFFFFFF;
- test_int2float(reporter, ival);
- test_int2float(reporter, -ival);
- }
}
}