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1# gzip-like LZSS compressor
2# Copyright (C) 2018 Pacien TRAN-GIRARD
3#
4# This program is free software: you can redistribute it and/or modify
5# it under the terms of the GNU Affero General Public License as
6# published by the Free Software Foundation, either version 3 of the
7# License, or (at your option) any later version.
8#
9# This program is distributed in the hope that it will be useful,
10# but WITHOUT ANY WARRANTY; without even the implied warranty of
11# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12# GNU Affero General Public License for more details.
13#
14# You should have received a copy of the GNU Affero General Public License
15# along with this program. If not, see <https://www.gnu.org/licenses/>.
16
17import ../bitio/integers, ../bitio/bitreader, ../bitio/bitwriter
18
19const maxDataBitLength = high(uint16).int
20const bitLengthFieldBitLength = 2 * wordBitLength
21
22type RawBlock* = object
23 bitLength: int
24 data: seq[uint8]
25
26proc readSerialised*(bitReader: BitReader): RawBlock =
27 let bitLength = bitReader.readBits(bitLengthFieldBitLength, uint16).int
28 let data = bitReader.readSeq(bitLength, uint8)
29 RawBlock(bitLength: bitLength, data: data.data)
30
31proc writeSerialisedTo*(rawBlock: RawBlock, bitWriter: BitWriter) =
32 bitWriter.writeBits(bitLengthFieldBitLength, rawBlock.bitLength.uint16)
33 bitWriter.writeSeq(rawBlock.bitLength, rawBlock.data)
34
35proc readRaw*(bitReader: BitReader, bits: int = maxDataBitLength): RawBlock =
36 let data = bitReader.readSeq(bits, uint8)
37 RawBlock(bitLength: data.bitLength, data: data.data)
38
39proc writeRawTo*(rawBlock: RawBlock, bitWriter: BitWriter) =
40 bitWriter.writeSeq(rawBlock.bitLength, rawBlock.data)