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 // Copyright 2017 The Chromium Authors // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #include #include "media/video/half_float_maker.h" #include "testing/gtest/include/gtest/gtest.h" namespace media { class HalfFloatMakerTest : public testing::Test {}; // Convert an IEEE 754 half-float to a double value // that we can do math on. double FromHalfFloat(uint16_t half_float) { if (!half_float) return 0.0; int sign = (half_float & 0x8000) ? -1 : 1; int exponent = (half_float >> 10) & 0x1F; int fraction = half_float & 0x3FF; if (exponent == 0) { return pow(2.0, -24.0) * fraction; } else if (exponent == 0x1F) { return sign * 1000000000000.0; } else { return pow(2.0, exponent - 25) * (0x400 + fraction); } } TEST_F(HalfFloatMakerTest, MakeHalfFloatTest) { unsigned short integers[1 << 16]; unsigned short half_floats[1 << 16]; for (int bits = 9; bits <= 16; bits++) { std::unique_ptr half_float_maker; half_float_maker = media::HalfFloatMaker::NewHalfFloatMaker(bits); int num_values = 1 << bits; for (int i = 0; i < num_values; i++) integers[i] = i; half_float_maker->MakeHalfFloats(integers, num_values, half_floats); // Multiplier to converting integers to 0.0..1.0 range. double multiplier = 1.0 / (num_values - 1); for (int i = 0; i < num_values; i++) { // This value is in range 0..1 float value = integers[i] * multiplier; // Reverse the effect of offset and multiplier to get the expected // output value from the half-float converter. float expected_value = value / half_float_maker->Multiplier() + half_float_maker->Offset(); EXPECT_EQ(integers[i], i); // We expect the result to be within +/- one least-significant bit. // Within the range we care about, half-floats values and // their representation both sort in the same order, so we // can just add one to get the next bigger half-float. float expected_precision = FromHalfFloat(half_floats[i] + 1) - FromHalfFloat(half_floats[i]); EXPECT_NEAR(FromHalfFloat(half_floats[i]), expected_value, expected_precision) << "i = " << i << " bits = " << bits; } } } } // namespace media