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- // Copyright 2017 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include <math.h>
- #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<media::HalfFloatMaker> 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
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