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// Copyright 2018 PDFium 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 "core/fxcrt/cfx_bitstream.h"
#include "testing/gtest/include/gtest/gtest.h"
namespace {
uint32_t ReferenceGetBits32(const uint8_t* pData, int bitpos, int nbits) {
int result = 0;
for (int i = 0; i < nbits; i++) {
if (pData[(bitpos + i) / 8] & (1 << (7 - (bitpos + i) % 8)))
result |= 1 << (nbits - i - 1);
}
return result;
}
} // namespace
TEST(fxcrt, BitStream) {
static const uint8_t kData[] = {0x00, 0x11, 0x22, 0x33,
0x44, 0x55, 0x66, 0x77};
CFX_BitStream bitstream(kData);
// Initial state.
EXPECT_FALSE(bitstream.IsEOF());
EXPECT_EQ(0U, bitstream.GetPos());
EXPECT_EQ(64U, bitstream.BitsRemaining());
// Read, read, read!
EXPECT_EQ(0x00U, bitstream.GetBits(8));
EXPECT_EQ(8U, bitstream.GetPos());
EXPECT_EQ(56U, bitstream.BitsRemaining());
EXPECT_EQ(0x00U, bitstream.GetBits(1));
EXPECT_EQ(9U, bitstream.GetPos());
EXPECT_EQ(55U, bitstream.BitsRemaining());
EXPECT_EQ(0x00U, bitstream.GetBits(2));
EXPECT_EQ(11U, bitstream.GetPos());
EXPECT_EQ(53U, bitstream.BitsRemaining());
EXPECT_EQ(0x04U, bitstream.GetBits(3));
EXPECT_EQ(14U, bitstream.GetPos());
EXPECT_EQ(50U, bitstream.BitsRemaining());
EXPECT_EQ(0x04U, bitstream.GetBits(4));
EXPECT_EQ(18U, bitstream.GetPos());
EXPECT_EQ(46U, bitstream.BitsRemaining());
EXPECT_EQ(0x44U, bitstream.GetBits(7));
EXPECT_EQ(25U, bitstream.GetPos());
EXPECT_EQ(39U, bitstream.BitsRemaining());
EXPECT_EQ(0xCDU, bitstream.GetBits(9));
EXPECT_EQ(34U, bitstream.GetPos());
EXPECT_EQ(30U, bitstream.BitsRemaining());
EXPECT_EQ(0x08AAU, bitstream.GetBits(15));
EXPECT_EQ(49U, bitstream.GetPos());
EXPECT_EQ(15U, bitstream.BitsRemaining());
// Cannot advance past the end.
EXPECT_EQ(0x00U, bitstream.GetBits(16));
EXPECT_EQ(49U, bitstream.GetPos());
EXPECT_EQ(15U, bitstream.BitsRemaining());
// Make sure SkipBits() works.
bitstream.SkipBits(14);
EXPECT_EQ(63U, bitstream.GetPos());
EXPECT_EQ(1U, bitstream.BitsRemaining());
bitstream.SkipBits(2);
EXPECT_EQ(65U, bitstream.GetPos());
EXPECT_EQ(0U, bitstream.BitsRemaining());
EXPECT_TRUE(bitstream.IsEOF());
// Make sure Rewind() works.
bitstream.Rewind();
EXPECT_FALSE(bitstream.IsEOF());
EXPECT_EQ(0U, bitstream.GetPos());
EXPECT_EQ(64U, bitstream.BitsRemaining());
// Read some more.
bitstream.SkipBits(5);
EXPECT_EQ(5U, bitstream.GetPos());
EXPECT_EQ(59U, bitstream.BitsRemaining());
EXPECT_EQ(0x0448U, bitstream.GetBits(17));
EXPECT_EQ(22U, bitstream.GetPos());
EXPECT_EQ(42U, bitstream.BitsRemaining());
// Make sure ByteAlign() works.
bitstream.ByteAlign();
EXPECT_EQ(24U, bitstream.GetPos());
EXPECT_EQ(40U, bitstream.BitsRemaining());
EXPECT_EQ(0x19A22AB3U, bitstream.GetBits(31));
EXPECT_EQ(55U, bitstream.GetPos());
EXPECT_EQ(9U, bitstream.BitsRemaining());
// Do some bigger reads.
bitstream.Rewind();
EXPECT_EQ(0x112233U, bitstream.GetBits(32));
EXPECT_EQ(32U, bitstream.GetPos());
EXPECT_EQ(32U, bitstream.BitsRemaining());
bitstream.Rewind();
bitstream.SkipBits(31);
EXPECT_EQ(0xA22AB33BU, bitstream.GetBits(32));
EXPECT_EQ(63U, bitstream.GetPos());
EXPECT_EQ(1U, bitstream.BitsRemaining());
// Skip past the end.
bitstream.SkipBits(1000);
EXPECT_TRUE(bitstream.IsEOF());
EXPECT_EQ(1063U, bitstream.GetPos());
EXPECT_EQ(0U, bitstream.BitsRemaining());
}
TEST(fxcrt, BitStreamSameAsReferenceGetBits32) {
unsigned char kData[] = {0xDE, 0x3F, 0xB1, 0x7C, 0x12, 0x9A, 0x04, 0x56};
CFX_BitStream bitstream(kData);
for (int nbits = 1; nbits <= 32; ++nbits) {
for (size_t bitpos = 0; bitpos < sizeof(kData) * 8 - nbits; ++bitpos) {
bitstream.Rewind();
bitstream.SkipBits(bitpos);
EXPECT_EQ(bitstream.GetBits(nbits),
ReferenceGetBits32(kData, bitpos, nbits));
}
}
}
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