1 files changed, 79 insertions, 0 deletions
diff --git a/core/fxcodec/gif/lzw_decompressor.h b/core/fxcodec/gif/lzw_decompressor.h
new file mode 100644
index 000000000..c078fc8c9
--- /dev/null
+++ b/core/fxcodec/gif/lzw_decompressor.h
@@ -0,0 +1,79 @@
+// Copyright 2017 The PDFium Authors
+// 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. http://www.foxitsoftware.com
+
+#ifndef CORE_FXCODEC_GIF_LZW_DECOMPRESSOR_H_
+#define CORE_FXCODEC_GIF_LZW_DECOMPRESSOR_H_
+
+#include <stdint.h>
+
+#include <memory>
+
+#include "core/fxcodec/gif/cfx_gif.h"
+#include "core/fxcrt/data_vector.h"
+
+namespace fxcodec {
+
+class LZWDecompressor {
+ public:
+  enum class Status {
+    kError,
+    kSuccess,
+    kUnfinished,
+    kInsufficientDestSize,
+  };
+
+  struct CodeEntry {
+    uint16_t prefix;
+    uint8_t suffix;
+  };
+
+  // Returns nullptr on error
+  static std::unique_ptr<LZWDecompressor> Create(uint8_t color_exp,
+                                                 uint8_t code_exp);
+  ~LZWDecompressor();
+
+  void SetSource(const uint8_t* src_buf, uint32_t src_size);
+  Status Decode(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);
+  }
+
+  DataVector<uint8_t>* DecompressedForTest() { return &decompressed_; }
+  size_t* DecompressedNextForTest() { return &decompressed_next_; }
+
+ private:
+  // Use Create() instead.
+  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;
+  DataVector<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];
+};
+
+}  // namespace fxcodec
+
+using LZWDecompressor = fxcodec::LZWDecompressor;
+
+#endif  // CORE_FXCODEC_GIF_LZW_DECOMPRESSOR_H_