/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_SnappyFrameUtils_h__

#define mozilla_SnappyFrameUtils_h__

#include "mozilla/Attributes.h"

#include "nsError.h"

namespace mozilla {

namespace detail {

//

// Utility class providing primitives necessary to build streams based

// on the snappy compressor.  This essentially abstracts the framing format

// defined in:

//

//  other-licences/snappy/src/framing_format.txt

//

// NOTE: Currently only the StreamIdentifier and CompressedData chunks are

//       supported.

//

class SnappyFrameUtils

{

public:

  enum ChunkType

  {

    Unknown,

    StreamIdentifier,

    CompressedData,

    UncompressedData,

    Padding,

    Reserved,

    ChunkTypeCount

  };

  static const size_t kChunkTypeLength = 1;

  static const size_t kChunkLengthLength = 3;

  static const size_t kHeaderLength = kChunkTypeLength + kChunkLengthLength;

  static const size_t kStreamIdentifierDataLength = 6;

  static const size_t kCRCLength = 4;

  static nsresult

  WriteStreamIdentifier(char* aDest, size_t aDestLength,

                        size_t* aBytesWrittenOut);

  static nsresult

  WriteCompressedData(char* aDest, size_t aDestLength,

                      const char* aData, size_t aDataLength,

                      size_t* aBytesWrittenOut);

  static nsresult

  ParseHeader(const char* aSource, size_t aSourceLength, ChunkType* aTypeOut,

              size_t* aDataLengthOut);

  static nsresult

  ParseData(char* aDest, size_t aDestLength,

            ChunkType aType, const char* aData, size_t aDataLength,

            size_t* aBytesWrittenOut, size_t* aBytesReadOut);

  static nsresult

  ParseStreamIdentifier(char* aDest, size_t aDestLength,

                        const char* aData, size_t aDataLength,

                        size_t* aBytesWrittenOut, size_t* aBytesReadOut);

  static nsresult

  ParseCompressedData(char* aDest, size_t aDestLength,

                      const char* aData, size_t aDataLength,

                      size_t* aBytesWrittenOut, size_t* aBytesReadOut);

  static size_t

  MaxCompressedBufferLength(size_t aSourceLength);

protected:

  SnappyFrameUtils() { }

  virtual ~SnappyFrameUtils() { }

};

} // namespace detail

} // namespace mozilla

#endif // mozilla_SnappyFrameUtils_h__