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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/>.
const wordBitLength* = 8
proc `/^`*[T: Natural](x, y: T): T =
(x + y - 1) div y
proc truncateToUint8*(x: SomeUnsignedInt): uint8 =
(x and uint8.high).uint8
proc bitLength*[T: SomeUnsignedInt](x: T): int =
var buf = x
while buf > 0.T:
buf = buf shr 1
result += 1
proc leastSignificantBits*[T: SomeUnsignedInt](x: T, bits: int): T =
let maskOffset = sizeof(T) * wordBitLength - bits
if maskOffset >= 0: (x shl maskOffset) shr maskOffset else: x
iterator chunks*(totalBitLength: int, chunkType: typedesc[SomeInteger]): tuple[index: int, chunkBitLength: int] =
let chunkBitLength = sizeof(chunkType) * wordBitLength
let wordCount = totalBitLength div chunkBitLength
for i in 0..<(wordCount): yield (i, chunkBitLength)
let remainder = totalBitLength mod chunkBitLength
if remainder > 0: yield (wordCount, remainder)
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