EXPECT_DOUBLE_EQ(0.333251953125, fp16_to_fp64(0x3555));
}
-TEST(FP16Test, NaN) {
- EXPECT_EQ(0xfe00, fp64_to_fp16(0.0 / 0.0));
- EXPECT_TRUE(isnan(fp16_to_fp64(0xfe00)));
+TEST(FP16Test, RoundToNearestEven) {
+ ASSERT_DOUBLE_EQ(1.0, fp16_to_fp64(0x3c00));
+
+ double x0 = fp16_to_fp64(0x3c00);
+ double x1 = fp16_to_fp64(0x3c01);
+ double x2 = fp16_to_fp64(0x3c02);
+ double x3 = fp16_to_fp64(0x3c03);
+ double x4 = fp16_to_fp64(0x3c04);
+
+ EXPECT_EQ(0x3c00, fp64_to_fp16(0.5 * (x0 + x1)));
+ EXPECT_EQ(0x3c02, fp64_to_fp16(0.5 * (x1 + x2)));
+ EXPECT_EQ(0x3c02, fp64_to_fp16(0.5 * (x2 + x3)));
+ EXPECT_EQ(0x3c04, fp64_to_fp16(0.5 * (x3 + x4)));
}
union fp64 {
unsigned int u;
};
+TEST(FP16Test, NaN) {
+ // Ignore the sign bit.
+ EXPECT_EQ(0x7e00, fp64_to_fp16(0.0 / 0.0) & 0x7fff);
+ EXPECT_TRUE(isnan(fp16_to_fp64(0xfe00)));
+
+ fp64 borderline_inf;
+ borderline_inf.ll = 0x7ff0000000000000ull;
+ fp64 borderline_nan;
+ borderline_nan.ll = 0x7ff0000000000001ull;
+
+ ASSERT_FALSE(isfinite(borderline_inf.f));
+ ASSERT_FALSE(isnan(borderline_inf.f));
+
+ ASSERT_FALSE(isfinite(borderline_nan.f));
+ ASSERT_TRUE(isnan(borderline_nan.f));
+
+ double borderline_inf_roundtrip = fp16_to_fp64(fp64_to_fp16(borderline_inf.f));
+ double borderline_nan_roundtrip = fp16_to_fp64(fp64_to_fp16(borderline_nan.f));
+
+ EXPECT_FALSE(isfinite(borderline_inf_roundtrip));
+ EXPECT_FALSE(isnan(borderline_inf_roundtrip));
+
+ EXPECT_FALSE(isfinite(borderline_nan_roundtrip));
+ EXPECT_TRUE(isnan(borderline_nan_roundtrip));
+}
+
+TEST(FP16Test, Denormals) {
+ const double smallest_fp16_denormal = 5.9604644775390625e-08;
+ EXPECT_EQ(0x0001, fp64_to_fp16(smallest_fp16_denormal));
+ EXPECT_EQ(0x0000, fp64_to_fp16(0.5 * smallest_fp16_denormal)); // Round-to-even.
+ EXPECT_EQ(0x0001, fp64_to_fp16(0.51 * smallest_fp16_denormal));
+ EXPECT_EQ(0x0002, fp64_to_fp16(1.5 * smallest_fp16_denormal));
+
+ const double smallest_fp16_non_denormal = 6.103515625e-05;
+ EXPECT_EQ(0x0400, fp64_to_fp16(smallest_fp16_non_denormal));
+ EXPECT_EQ(0x0400, fp64_to_fp16(smallest_fp16_non_denormal - 0.5 * smallest_fp16_denormal)); // Round-to-even.
+ EXPECT_EQ(0x03ff, fp64_to_fp16(smallest_fp16_non_denormal - smallest_fp16_denormal));
+}
+
// Randomly test a large number of fp64 -> fp32 conversions, comparing
// against the FPU.
TEST(FP16Test, FP32ReferenceDownconvert) {