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5af152c214
With intent to replace BitBuffer. This version is optimised for binary size and readability of the parsers at the cost of slower parsing of invalid bitstreams Bug: None Change-Id: Ib054e2a7758b9a69cbf2559e739465b104a7dcf3 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/230244 Commit-Queue: Danil Chapovalov <danilchap@webrtc.org> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Reviewed-by: Erik Språng <sprang@webrtc.org> Cr-Commit-Position: refs/heads/main@{#34886}
335 lines
11 KiB
C++
335 lines
11 KiB
C++
/*
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* Copyright 2021 The WebRTC Project Authors. All rights reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "rtc_base/bitstream_reader.h"
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#include <stddef.h>
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#include <stdint.h>
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#include <array>
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#include <limits>
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#include "absl/numeric/bits.h"
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#include "absl/types/optional.h"
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#include "api/array_view.h"
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#include "rtc_base/checks.h"
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#include "test/gmock.h"
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#include "test/gtest.h"
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namespace webrtc {
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namespace {
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TEST(BitstreamReaderTest, InDebugModeRequiresToCheckOkStatusBeforeDestruction) {
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const uint8_t bytes[32] = {};
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absl::optional<BitstreamReader> reader(absl::in_place, bytes);
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EXPECT_GE(reader->ReadBits(7), 0u);
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#if RTC_DCHECK_IS_ON && GTEST_HAS_DEATH_TEST && !defined(OS_ANDROID)
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EXPECT_DEATH(reader = absl::nullopt, "");
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#endif
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EXPECT_TRUE(reader->Ok());
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reader = absl::nullopt;
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}
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TEST(BitstreamReaderTest, InDebugModeMayCheckRemainingBitsInsteadOfOkStatus) {
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const uint8_t bytes[32] = {};
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absl::optional<BitstreamReader> reader(absl::in_place, bytes);
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EXPECT_GE(reader->ReadBit(), 0);
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#if RTC_DCHECK_IS_ON && GTEST_HAS_DEATH_TEST && !defined(OS_ANDROID)
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EXPECT_DEATH(reader = absl::nullopt, "");
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#endif
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EXPECT_GE(reader->RemainingBitCount(), 0);
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reader = absl::nullopt;
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}
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TEST(BitstreamReaderTest, ConsumeBits) {
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const uint8_t bytes[32] = {};
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BitstreamReader reader(bytes);
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int total_bits = 32 * 8;
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EXPECT_EQ(reader.RemainingBitCount(), total_bits);
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reader.ConsumeBits(3);
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total_bits -= 3;
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EXPECT_EQ(reader.RemainingBitCount(), total_bits);
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reader.ConsumeBits(3);
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total_bits -= 3;
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EXPECT_EQ(reader.RemainingBitCount(), total_bits);
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reader.ConsumeBits(15);
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total_bits -= 15;
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EXPECT_EQ(reader.RemainingBitCount(), total_bits);
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reader.ConsumeBits(67);
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total_bits -= 67;
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EXPECT_EQ(reader.RemainingBitCount(), total_bits);
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EXPECT_TRUE(reader.Ok());
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reader.ConsumeBits(32 * 8);
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EXPECT_FALSE(reader.Ok());
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EXPECT_LT(reader.RemainingBitCount(), 0);
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}
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TEST(BitstreamReaderTest, ReadBit) {
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const uint8_t bytes[] = {0b0100'0001, 0b1011'0001};
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BitstreamReader reader(bytes);
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// First byte.
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EXPECT_EQ(reader.ReadBit(), 0);
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EXPECT_EQ(reader.ReadBit(), 1);
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EXPECT_EQ(reader.ReadBit(), 0);
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EXPECT_EQ(reader.ReadBit(), 0);
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EXPECT_EQ(reader.ReadBit(), 0);
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EXPECT_EQ(reader.ReadBit(), 0);
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EXPECT_EQ(reader.ReadBit(), 0);
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EXPECT_EQ(reader.ReadBit(), 1);
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// Second byte.
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EXPECT_EQ(reader.ReadBit(), 1);
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EXPECT_EQ(reader.ReadBit(), 0);
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EXPECT_EQ(reader.ReadBit(), 1);
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EXPECT_EQ(reader.ReadBit(), 1);
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EXPECT_EQ(reader.ReadBit(), 0);
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EXPECT_EQ(reader.ReadBit(), 0);
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EXPECT_EQ(reader.ReadBit(), 0);
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EXPECT_EQ(reader.ReadBit(), 1);
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EXPECT_TRUE(reader.Ok());
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// Try to read beyound the buffer.
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EXPECT_EQ(reader.ReadBit(), 0);
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EXPECT_FALSE(reader.Ok());
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}
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TEST(BitstreamReaderTest, ReadBoolConsumesSingleBit) {
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const uint8_t bytes[] = {0b1010'1010};
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BitstreamReader reader(bytes);
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ASSERT_EQ(reader.RemainingBitCount(), 8);
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EXPECT_TRUE(reader.Read<bool>());
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EXPECT_EQ(reader.RemainingBitCount(), 7);
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}
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TEST(BitstreamReaderTest, ReadBytesAligned) {
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const uint8_t bytes[] = {0x0A, //
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0xBC, //
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0xDE, 0xF1, //
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0x23, 0x45, 0x67, 0x89};
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BitstreamReader reader(bytes);
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EXPECT_EQ(reader.Read<uint8_t>(), 0x0Au);
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EXPECT_EQ(reader.Read<uint8_t>(), 0xBCu);
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EXPECT_EQ(reader.Read<uint16_t>(), 0xDEF1u);
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EXPECT_EQ(reader.Read<uint32_t>(), 0x23456789u);
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EXPECT_TRUE(reader.Ok());
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}
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TEST(BitstreamReaderTest, ReadBytesOffset4) {
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const uint8_t bytes[] = {0x0A, 0xBC, 0xDE, 0xF1, 0x23,
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0x45, 0x67, 0x89, 0x0A};
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BitstreamReader reader(bytes);
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reader.ConsumeBits(4);
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EXPECT_EQ(reader.Read<uint8_t>(), 0xABu);
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EXPECT_EQ(reader.Read<uint8_t>(), 0xCDu);
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EXPECT_EQ(reader.Read<uint16_t>(), 0xEF12u);
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EXPECT_EQ(reader.Read<uint32_t>(), 0x34567890u);
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EXPECT_TRUE(reader.Ok());
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}
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TEST(BitstreamReaderTest, ReadBytesOffset3) {
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// The pattern we'll check against is counting down from 0b1111. It looks
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// weird here because it's all offset by 3.
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// Byte pattern is:
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// 56701234
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// 0b00011111,
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// 0b11011011,
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// 0b10010111,
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// 0b01010011,
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// 0b00001110,
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// 0b11001010,
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// 0b10000110,
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// 0b01000010
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// xxxxx <-- last 5 bits unused.
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// The bytes. It almost looks like counting down by two at a time, except the
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// jump at 5->3->0, since that's when the high bit is turned off.
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const uint8_t bytes[] = {0x1F, 0xDB, 0x97, 0x53, 0x0E, 0xCA, 0x86, 0x42};
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BitstreamReader reader(bytes);
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reader.ConsumeBits(3);
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EXPECT_EQ(reader.Read<uint8_t>(), 0xFEu);
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EXPECT_EQ(reader.Read<uint16_t>(), 0xDCBAu);
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EXPECT_EQ(reader.Read<uint32_t>(), 0x98765432u);
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EXPECT_TRUE(reader.Ok());
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// 5 bits left unread. Not enough to read a uint8_t.
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EXPECT_EQ(reader.RemainingBitCount(), 5);
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EXPECT_EQ(reader.Read<uint8_t>(), 0);
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EXPECT_FALSE(reader.Ok());
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}
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TEST(BitstreamReaderTest, ReadBits) {
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const uint8_t bytes[] = {0b010'01'101, 0b0011'00'1'0};
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BitstreamReader reader(bytes);
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EXPECT_EQ(reader.ReadBits(3), 0b010u);
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EXPECT_EQ(reader.ReadBits(2), 0b01u);
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EXPECT_EQ(reader.ReadBits(7), 0b101'0011u);
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EXPECT_EQ(reader.ReadBits(2), 0b00u);
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EXPECT_EQ(reader.ReadBits(1), 0b1u);
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EXPECT_EQ(reader.ReadBits(1), 0b0u);
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EXPECT_TRUE(reader.Ok());
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EXPECT_EQ(reader.ReadBits(1), 0u);
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EXPECT_FALSE(reader.Ok());
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}
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TEST(BitstreamReaderTest, ReadZeroBits) {
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BitstreamReader reader(rtc::ArrayView<const uint8_t>(nullptr, 0));
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EXPECT_EQ(reader.ReadBits(0), 0u);
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EXPECT_TRUE(reader.Ok());
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}
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TEST(BitstreamReaderTest, ReadBitFromEmptyArray) {
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BitstreamReader reader(rtc::ArrayView<const uint8_t>(nullptr, 0));
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// Trying to read from the empty array shouldn't dereference the pointer,
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// i.e. shouldn't crash.
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EXPECT_EQ(reader.ReadBit(), 0);
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EXPECT_FALSE(reader.Ok());
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}
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TEST(BitstreamReaderTest, ReadBitsFromEmptyArray) {
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BitstreamReader reader(rtc::ArrayView<const uint8_t>(nullptr, 0));
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// Trying to read from the empty array shouldn't dereference the pointer,
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// i.e. shouldn't crash.
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EXPECT_EQ(reader.ReadBits(1), 0u);
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EXPECT_FALSE(reader.Ok());
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}
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TEST(BitstreamReaderTest, ReadBits64) {
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const uint8_t bytes[] = {0x4D, 0x32, 0xAB, 0x54, 0x00, 0xFF, 0xFE, 0x01,
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0xAB, 0xCD, 0xEF, 0x01, 0x23, 0x45, 0x67, 0x89};
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BitstreamReader reader(bytes);
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EXPECT_EQ(reader.ReadBits(33), 0x4D32AB5400FFFE01u >> (64 - 33));
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constexpr uint64_t kMask31Bits = (1ull << 32) - 1;
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EXPECT_EQ(reader.ReadBits(31), 0x4D32AB5400FFFE01ull & kMask31Bits);
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EXPECT_EQ(reader.ReadBits(64), 0xABCDEF0123456789ull);
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EXPECT_TRUE(reader.Ok());
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// Nothing more to read.
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EXPECT_EQ(reader.ReadBit(), 0);
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EXPECT_FALSE(reader.Ok());
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}
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TEST(BitstreamReaderTest, CanPeekBitsUsingCopyConstructor) {
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// BitstreamReader doesn't have peek function. To simulate it, user may use
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// cheap BitstreamReader copy constructor.
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const uint8_t bytes[] = {0x0A, 0xBC};
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BitstreamReader reader(bytes);
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reader.ConsumeBits(4);
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ASSERT_EQ(reader.RemainingBitCount(), 12);
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BitstreamReader peeker = reader;
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EXPECT_EQ(peeker.ReadBits(8), 0xABu);
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EXPECT_EQ(peeker.RemainingBitCount(), 4);
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EXPECT_EQ(reader.RemainingBitCount(), 12);
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// Can resume reading from before peeker was created.
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EXPECT_EQ(reader.ReadBits(4), 0xAu);
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EXPECT_EQ(reader.RemainingBitCount(), 8);
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}
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TEST(BitstreamReaderTest,
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ReadNonSymmetricSameNumberOfBitsWhenNumValuesPowerOf2) {
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const uint8_t bytes[2] = {0xf3, 0xa0};
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BitstreamReader reader(bytes);
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ASSERT_EQ(reader.RemainingBitCount(), 16);
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EXPECT_EQ(reader.ReadNonSymmetric(/*num_values=*/1 << 4), 0xfu);
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EXPECT_EQ(reader.ReadNonSymmetric(/*num_values=*/1 << 4), 0x3u);
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EXPECT_EQ(reader.ReadNonSymmetric(/*num_values=*/1 << 4), 0xau);
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EXPECT_EQ(reader.ReadNonSymmetric(/*num_values=*/1 << 4), 0x0u);
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EXPECT_EQ(reader.RemainingBitCount(), 0);
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EXPECT_TRUE(reader.Ok());
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}
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TEST(BitstreamReaderTest, ReadNonSymmetricOnlyValueConsumesZeroBits) {
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const uint8_t bytes[2] = {};
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BitstreamReader reader(bytes);
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ASSERT_EQ(reader.RemainingBitCount(), 16);
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EXPECT_EQ(reader.ReadNonSymmetric(/*num_values=*/1), 0u);
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EXPECT_EQ(reader.RemainingBitCount(), 16);
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}
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std::array<uint8_t, 8> GolombEncoded(uint32_t val) {
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int val_width = absl::bit_width(val + 1);
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int total_width = 2 * val_width - 1;
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uint64_t representation = (uint64_t{val} + 1) << (64 - total_width);
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std::array<uint8_t, 8> result;
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for (int i = 0; i < 8; ++i) {
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result[i] = representation >> (7 - i) * 8;
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}
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return result;
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}
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TEST(BitstreamReaderTest, GolombUint32Values) {
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// Test over the uint32_t range with a large enough step that the test doesn't
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// take forever. Around 20,000 iterations should do.
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const int kStep = std::numeric_limits<uint32_t>::max() / 20000;
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for (uint32_t i = 0; i < std::numeric_limits<uint32_t>::max() - kStep;
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i += kStep) {
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std::array<uint8_t, 8> buffer = GolombEncoded(i);
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BitstreamReader reader(buffer);
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// Use assert instead of EXPECT to avoid spamming thousands of failed
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// expectation when this test fails.
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ASSERT_EQ(reader.ReadExponentialGolomb(), i);
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EXPECT_TRUE(reader.Ok());
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}
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}
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TEST(BitstreamReaderTest, SignedGolombValues) {
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uint8_t golomb_bits[][1] = {
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{0b1'0000000}, {0b010'00000}, {0b011'00000}, {0b00100'000}, {0b00111'000},
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};
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int expected[] = {0, 1, -1, 2, -3};
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for (size_t i = 0; i < sizeof(golomb_bits); ++i) {
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BitstreamReader reader(golomb_bits[i]);
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EXPECT_EQ(reader.ReadSignedExponentialGolomb(), expected[i])
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<< "Mismatch in expected/decoded value for golomb_bits[" << i
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<< "]: " << static_cast<int>(golomb_bits[i][0]);
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EXPECT_TRUE(reader.Ok());
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}
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}
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TEST(BitstreamReaderTest, NoGolombOverread) {
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const uint8_t bytes[] = {0x00, 0xFF, 0xFF};
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// Make sure the bit buffer correctly enforces byte length on golomb reads.
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// If it didn't, the above buffer would be valid at 3 bytes.
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BitstreamReader reader1(rtc::MakeArrayView(bytes, 1));
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// When parse fails, `ReadExponentialGolomb` may return any number.
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reader1.ReadExponentialGolomb();
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EXPECT_FALSE(reader1.Ok());
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BitstreamReader reader2(rtc::MakeArrayView(bytes, 2));
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reader2.ReadExponentialGolomb();
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EXPECT_FALSE(reader2.Ok());
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BitstreamReader reader3(bytes);
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// Golomb should have read 9 bits, so 0x01FF, and since it is golomb, the
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// result is 0x01FF - 1 = 0x01FE.
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EXPECT_EQ(reader3.ReadExponentialGolomb(), 0x01FEu);
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EXPECT_TRUE(reader3.Ok());
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}
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} // namespace
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} // namespace webrtc
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