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// Copyright 2017 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.
// Original code copyright 2014 Foxit Software Inc.
#include <memory>
#include <vector>
#include "core/fxcodec/gif/cfx_gif.h"
#include "core/fxcrt/fx_memory_wrappers.h"
class CFX_LZWDecompressor {
struct CodeEntry {
uint16_t prefix;
uint8_t suffix;
// Returns nullptr on error
static std::unique_ptr<CFX_LZWDecompressor> Create(uint8_t color_exp,
uint8_t code_exp);
CFX_GifDecodeStatus Decode(const uint8_t* src_buf,
uint32_t src_size,
uint8_t* dest_buf,
uint32_t* dest_size);
// Used by unittests, should not be called in production code.
uint32_t ExtractDataForTest(uint8_t* dest_buf, uint32_t dest_size) {
return ExtractData(dest_buf, dest_size);
std::vector<uint8_t, FxAllocAllocator<uint8_t>>* DecompressedForTest() {
return &decompressed_;
size_t* DecompressedNextForTest() { return &decompressed_next_; }
// Use Create() instead.
CFX_LZWDecompressor(uint8_t color_exp, uint8_t code_exp);
void ClearTable();
void AddCode(uint16_t prefix_code, uint8_t append_char);
bool DecodeString(uint16_t code);
uint32_t ExtractData(uint8_t* dest_buf, uint32_t dest_size);
const uint8_t code_size_;
uint8_t code_size_cur_ = 0;
const uint16_t code_color_end_;
const uint16_t code_clear_;
const uint16_t code_end_;
uint16_t code_next_ = 0;
uint8_t code_first_ = 0;
std::vector<uint8_t, FxAllocAllocator<uint8_t>> decompressed_;
size_t decompressed_next_ = 0;
uint16_t code_old_ = 0;
const uint8_t* next_in_ = nullptr;
uint32_t avail_in_ = 0;
uint8_t bits_left_ = 0;
uint32_t code_store_ = 0;
CodeEntry code_table_[GIF_MAX_LZW_CODE];