/*
* Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014
* Jonathan Schleifer <js@webkeks.org>
*
* All rights reserved.
*
* This file is part of ObjFW. It may be distributed under the terms of the
* Q Public License 1.0, which can be found in the file LICENSE.QPL included in
* the packaging of this file.
*
* Alternatively, it may be distributed under the terms of the GNU General
* Public License, either version 2 or 3, which can be found in the file
* LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
* file.
*/
#import "OFStream.h"
#define OF_DEFLATE_STREAM_BUFFER_SIZE 4096
/*!
* @brief A class for a stream that handles Deflate compression or decompression
* transparently for an underlying stream.
*/
@interface OFDeflateStream: OFStream
{
#ifdef OF_DEFLATE_STREAM_M
@public
#endif
OFStream *_stream;
uint8_t _buffer[OF_DEFLATE_STREAM_BUFFER_SIZE];
uint_fast16_t _bufferIndex, _bufferLength;
uint8_t _byte;
uint_fast8_t _bitIndex, _savedBitsLength;
uint_fast16_t _savedBits;
@protected
uint8_t *_slidingWindow;
uint_fast16_t _slidingWindowIndex, _slidingWindowMask;
struct {
uint_fast8_t numDistanceCodes;
const uint8_t *lengthCodes;
const uint8_t *lengthExtraBits;
const uint16_t *distanceCodes;
const uint8_t *distanceExtraBits;
} _codes;
enum {
OF_DEFLATE_STREAM_BLOCK_HEADER,
OF_DEFLATE_STREAM_UNCOMPRESSED_BLOCK_HEADER,
OF_DEFLATE_STREAM_UNCOMPRESSED_BLOCK,
OF_DEFLATE_STREAM_HUFFMAN_TREE,
OF_DEFLATE_STREAM_HUFFMAN_BLOCK
} _state;
union {
struct {
uint_fast8_t position;
uint8_t length[4];
} uncompressedHeader;
struct {
uint_fast16_t position, length;
} uncompressed;
struct {
struct huffman_tree *litLenTree, *distTree;
struct huffman_tree *codeLenTree, *treeIter;
uint8_t *lengths;
uint_fast16_t receivedCount;
uint_fast8_t value, litLenCodesCount, distCodesCount;
uint_fast8_t codeLenCodesCount;
} huffmanTree;
struct {
struct huffman_tree *litLenTree, *distTree, *treeIter;
enum {
OF_DEFLATE_STREAM_WRITE_VALUE,
OF_DEFLATE_STREAM_AWAIT_CODE,
OF_DEFLATE_STREAM_AWAIT_LENGTH_EXTRA_BITS,
OF_DEFLATE_STREAM_AWAIT_DISTANCE,
OF_DEFLATE_STREAM_AWAIT_DISTANCE_EXTRA_BITS,
OF_DEFLATE_STREAM_PROCESS_PAIR
} state;
uint_fast16_t value, length, distance;
uint_fast16_t extraBits;
} huffman;
} _context;
bool _inLastBlock, _atEndOfStream;
}
/*!
* @brief Creates a new OFDeflateStream with the specified underlying stream.
*
* @param stream The underlying stream to which compressed data is written or
* from which compressed data is read
* @return A new, autoreleased OFDeflateStream
*/
+ (instancetype)streamWithStream: (OFStream*)stream;
/*!
* @brief Initializes an already allocated OFDeflateStream with the specified
* underlying stream.
*
* @param stream The underlying stream to which compressed data is written or
* from which compressed data is read
* @return A initialized OFDeflateStream
*/
- initWithStream: (OFStream*)stream;
@end