114 lines
3.1 KiB
C++
114 lines
3.1 KiB
C++
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// Copyright 2017 The Chromium Authors
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "net/tools/huffman_trie/bit_writer.h"
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#include "testing/gmock/include/gmock/gmock.h"
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#include "testing/gtest/include/gtest/gtest.h"
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namespace net::huffman_trie {
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namespace {
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// Test that single bits are written to the buffer correctly.
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TEST(BitWriterTest, WriteBit) {
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BitWriter writer;
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EXPECT_EQ(0U, writer.position());
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EXPECT_EQ(0U, writer.bytes().size());
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writer.WriteBit(0);
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EXPECT_EQ(1U, writer.position());
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writer.WriteBit(1);
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writer.WriteBit(0);
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writer.WriteBit(1);
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writer.WriteBit(0);
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writer.WriteBit(1);
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writer.WriteBit(0);
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writer.WriteBit(1);
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EXPECT_EQ(8U, writer.position());
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writer.WriteBit(0);
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EXPECT_EQ(9U, writer.position());
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writer.WriteBit(1);
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writer.WriteBit(0);
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EXPECT_EQ(11U, writer.position());
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// Flush should pad the current byte with zero's until it's full.
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writer.Flush();
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// The writer should have 2 bytes now even though we only wrote 11 bits.
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EXPECT_EQ(16U, writer.position());
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// 0 + 1 + 0 + 1 + 0 + 1 + 0 + 1 + 0 + 1 + 0 + 00000 (padding) = 0x5540.
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EXPECT_THAT(writer.bytes(), testing::ElementsAre(0x55, 0x40));
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}
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// Test that when multiple bits are written to the buffer, they are appended
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// correctly.
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TEST(BitWriterTest, WriteBits) {
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BitWriter writer;
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// 0xAA is 10101010 in binary. WritBits will write the n least significant
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// bits where n is given as the second parameter.
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writer.WriteBits(0xAA, 1);
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EXPECT_EQ(1U, writer.position());
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writer.WriteBits(0xAA, 2);
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EXPECT_EQ(3U, writer.position());
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writer.WriteBits(0xAA, 3);
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EXPECT_EQ(6U, writer.position());
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writer.WriteBits(0xAA, 2);
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EXPECT_EQ(8U, writer.position());
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writer.WriteBits(0xAA, 2);
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EXPECT_EQ(10U, writer.position());
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// Flush should pad the current byte with zero's until it's full.
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writer.Flush();
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// The writer should have 2 bytes now even though we only wrote 10 bits.
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EXPECT_EQ(16U, writer.position());
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// 0 + 10 + 010 + 10 + 10 + 000000 (padding) = 0x4A80
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EXPECT_THAT(writer.bytes(), testing::ElementsAre(0x4A, 0x80));
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}
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// Test that buffering works correct when the methods are mixed.
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TEST(BitWriterTest, WriteBoth) {
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BitWriter writer;
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// 0xAA is 10101010 in binary. WritBits will write the n least significant
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// bits where n is given as the second parameter.
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writer.WriteBits(0xAA, 1);
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EXPECT_EQ(1U, writer.position());
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writer.WriteBit(1);
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writer.WriteBits(0xAA, 2);
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EXPECT_EQ(4U, writer.position());
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writer.WriteBits(0xAA, 3);
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EXPECT_EQ(7U, writer.position());
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writer.WriteBit(1);
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EXPECT_EQ(8U, writer.position());
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writer.WriteBits(0xAA, 2);
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writer.WriteBit(0);
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EXPECT_EQ(11U, writer.position());
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// Flush should pad the current byte with zero's until it's full.
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writer.Flush();
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// The writer should have 2 bytes now even though we only wrote 10 bits.
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EXPECT_EQ(16U, writer.position());
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// 0 + 1 + 10 + 010 + 1 + 10 + 0 + 00000 (padding) = 0x6580
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EXPECT_THAT(writer.bytes(), testing::ElementsAre(0x65, 0x80));
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}
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} // namespace
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} // namespace net::huffman_trie
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