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# 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 <https://www.gnu.org/licenses/>.
import sequtils
import ../bitio/integers, ../bitio/bitreader, ../bitio/bitwriter
import rawblock, lzssblock
type BlockKind* = enum
uncompressed = 0b00'u8,
lzss = 0b01,
reserved1 = 0b10,
reserved2 = 0b11
type StreamBlock* = object
last: bool
case kind: BlockKind
of uncompressed:
rawBlock: RawBlock
of lzss:
lzssBlock: LzssBlock
else:
discard
proc isLast*(streamBlock: StreamBlock): bool =
streamBlock.last
proc readSerialised*(bitReader: BitReader): StreamBlock =
result.last = bitReader.readBool()
result.kind = bitReader.readBits(2, uint8).BlockKind
case result.kind:
of uncompressed: result.rawBlock = rawblock.readSerialised(bitReader)
of lzss: result.lzssBlock = lzssblock.readSerialised(bitReader)
else: raise newException(ValueError, "unhandled block type")
proc writeSerialisedTo*(streamBlock: StreamBlock, bitWriter: BitWriter) =
bitWriter.writeBool(streamBlock.last)
bitWriter.writeBits(2, streamBlock.kind.uint8)
case streamBlock.kind:
of uncompressed: streamBlock.rawBlock.writeSerialisedTo(bitWriter)
of lzss: streamBlock.lzssBlock.writeSerialisedTo(bitWriter)
else: raise newException(ValueError, "unhandled block type")
proc readRaw*(bitReader: BitReader, kind: BlockKind = uncompressed): StreamBlock =
result.kind = kind
case kind:
of uncompressed: result.rawBlock = rawblock.readRaw(bitReader)
of lzss: result.lzssBlock = lzssblock.readRaw(bitReader)
else: raise newException(ValueError, "unhandled block type")
result.last = bitReader.atEnd()
proc writeRawTo*(streamBlock: StreamBlock, bitWriter: BitWriter) =
case streamBlock.kind:
of uncompressed: streamBlock.rawBlock.writeRawTo(bitWriter)
of lzss: streamBlock.lzssBlock.writeRawTo(bitWriter)
else: raise newException(ValueError, "unhandled block type")
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