Add brotli compressor

This commit is for the encoder for brotli compression format.
Brotli is a generic byte-level compression algorithm.

brotli/enc/prefix.h

@@ -0,0 +1,51 @@
+// Copyright 2013 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Functions for encoding of integers into prefix codes the amount of extra
+// bits, and the actual values of the extra bits.
+
+#ifndef BROTLI_ENC_PREFIX_H_
+#define BROTLI_ENC_PREFIX_H_
+
+#include <stdint.h>
+
+namespace brotli {
+
+static const int kNumInsertLenPrefixes = 24;
+static const int kNumCopyLenPrefixes = 24;
+static const int kNumCommandPrefixes = 704;
+static const int kNumBlockLenPrefixes = 26;
+static const int kNumDistanceShortCodes = 16;
+static const int kNumDistancePrefixes = 520;
+
+int CommandPrefix(int insert_length, int copy_length);
+int InsertLengthExtraBits(int prefix);
+int InsertLengthOffset(int prefix);
+int CopyLengthExtraBits(int prefix);
+int CopyLengthOffset(int prefix);
+
+void PrefixEncodeCopyDistance(int distance_code,
+                              int num_direct_codes,
+                              int shift_bits,
+                              uint16_t* prefix,
+                              int* nbits,
+                              uint32_t* extra_bits);
+
+int BlockLengthPrefix(int length);
+int BlockLengthExtraBits(int prefix);
+int BlockLengthOffset(int prefix);
+
+}  // namespace brotli
+
+#endif  // BROTLI_ENC_PREFIX_H_