Add static domain security state generator tool.

net/tools/domain_security_preload_generator/trie/trie_bit_buffer.h

+// Copyright (c) 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef NET_TOOLS_DOMAIN_SECURITY_PRELOAD_GENERATOR_TRIE_TRIE_BIT_BUFFER_H_
+#define NET_TOOLS_DOMAIN_SECURITY_PRELOAD_GENERATOR_TRIE_TRIE_BIT_BUFFER_H_
+
+#include <stdint.h>
+
+#include <vector>
+
+#include "net/tools/domain_security_preload_generator/bit_writer.h"
+#include "net/tools/domain_security_preload_generator/huffman/huffman_frequency_tracker.h"
+
+namespace net {
+
+// TrieBitBuffer acts as a buffer for TrieWriter. It can write bits, characters,
+// and positions. The characters are stored as their Huffmanrepresentation.
+// Positions are references to other locations in the trie.
+class TrieBitBuffer {
+ public:
+  TrieBitBuffer();
+  ~TrieBitBuffer();
+
+  // Write |bit| to the buffer.
+  void WriteBit(uint8_t bit);
+
+  // Write the last |number_of_bits| from |bits| to the buffer.
+  void WriteBits(uint32_t bits, uint8_t number_of_bits);
+
+  // Write a position the the buffer. Actually stores the difference between
+  // |position| and |last_position|. |last_position| will updated to equal the
+  // input |position|.
+  void WritePosition(int position, int* last_position);
+
+  // Write the character in |byte| to the buffer using its Huffman
+  // representation in |table|. Optionally tracks usage of the character in
+  // |tracker|.
+  void WriteChar(uint8_t byte,
+                 const HuffmanRepresentationTable& table,
+                 HuffmanFrequencyTracker* tracker);
+
+  // Write the entire buffer to |writer|.
+  uint32_t WriteToBitWriter(BitWriter& writer);
+
+  // Appends the buffered bits in |current_byte_| to |elements_|. empty bits
+  // are filled with zero's.
+  void Close();
+
+ private:
+  // Represents either the last |number_of_bits| bits in |bits| or a position
+  // (offset) in the trie.
+  struct BitsOrPosition {
+    uint8_t bits;
+    uint8_t number_of_bits;
+    int position;
+  };
+
+  // Returns the minimum number of bits needed to represent |input|.
+  uint8_t BitLength(int input) const;
+
+  // Append a new element to |elements_|.
+  void AppendBitsElement(uint8_t bits, uint8_t number_of_bits);
+  void AppendPositionElement(int position);
+
+  // Buffers bits until it can fill a byte.
+  uint8_t current_byte_;
+
+  // The number of bits currently in |current_byte_|.
+  uint32_t used_;
+
+  std::vector<BitsOrPosition> elements_;
+};
+
+}  // namespace net
+
+#endif  // NET_TOOLS_DOMAIN_SECURITY_PRELOAD_GENERATOR_TRIE_TRIE_BIT_BUFFER_H_