# gzip-like LZSS compressor # Copyright (C) 2018 Pacien TRAN-GIRARD # # This program is free software: you can redistribute it and/or modify # it under the terms of the GNU Affero General Public License as # published by the Free Software Foundation, either version 3 of the # License, or (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU Affero General Public License for more details. # # You should have received a copy of the GNU Affero General Public License # along with this program. If not, see . import ../bitio/bitreader import ../lzss/lzssnode, ../lzss/lzsschain import ../huffman/huffmantree, ../huffman/huffmandecoder import lzsshuffmansymbol proc readChain*(bitReader: BitReader, symbolDecoder, positionDecoder: HuffmanDecoder[uint16], maxDataByteLength: int): LzssChain = var chain = lzssChain() var (symbol, byteCursor) = (symbolDecoder.decode(bitReader).Symbol, 0) while not symbol.isEndMarker(): if byteCursor > maxDataByteLength: raise newException(IOError, "lzss block too long") if symbol.isCharacter(): chain.add(lzssCharacter(symbol.uint8)) else: let position = positionDecoder.decode(bitReader) chain.add(unpackLzssReference(symbol, position)) (symbol, byteCursor) = (symbolDecoder.decode(bitReader).Symbol, byteCursor + 1) chain