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Finished first implementation draft.

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This commit is contained in:
Timofey Solomko
2016-12-16 20:01:21 +03:00
parent 7ac6cc2447
commit 0664e5e481
1 changed files with 117 additions and 14 deletions
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Sources/LZMA.swift
+117 -14
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@@ -49,6 +49,10 @@ public final class LZMA: DecompressionAlgorithm {
private(set) var totalPosition: Int
var isEmpty: Bool {
return self.position == 0 && !self.isFull
}
init(dictSize: Int) {
self.byteBuffer = Array(repeating: 0, count: dictSize)
self.position = 0
@@ -83,10 +87,6 @@ public final class LZMA: DecompressionAlgorithm {
return distance <= self.position || self.isFull
}
func isEmpty() -> Bool {
return self.position == 0 && !self.isFull
}
}
final class RangeDecoder {
@@ -95,6 +95,10 @@ public final class LZMA: DecompressionAlgorithm {
private var code: Int
private(set) var isCorrupted: Bool
var isFinishedOK: Bool {
return self.code == 0
}
init?(pointerData: inout DataWithPointer) {
self.isCorrupted = false
self.range = 0xFFFFFFFF
@@ -110,10 +114,6 @@ public final class LZMA: DecompressionAlgorithm {
}
}
func isFinishedOK() -> Bool {
return self.code == 0
}
func normalize(pointerData: inout DataWithPointer) {
if self.range < Constants.topValue {
self.range <<= 8
@@ -302,9 +302,10 @@ public final class LZMA: DecompressionAlgorithm {
var state = 0
func decodeLiteral(_ state: Int, _ rep0: Int) {
let prevByte = outWindow.isEmpty() ? 0 : outWindow.byte(at: 1)
let prevByte = outWindow.isEmpty ? 0 : outWindow.byte(at: 1)
// TODO: Something is not quite right.
var symbol = 1
var litState = ((outWindow.totalPosition & ((1 << lp.toInt()) - 1)) << lc.toInt()) + (prevByte >> (8 - lc)).toInt()
let litState = ((outWindow.totalPosition & ((1 << lp.toInt()) - 1)) << lc.toInt()) + (prevByte >> (8 - lc)).toInt()
let probsIndex = 0x300 * litState
if state >= 7 {
var matchByte = outWindow.byte(at: rep0 + 1)
@@ -322,20 +323,45 @@ public final class LZMA: DecompressionAlgorithm {
while symbol < 0x100 {
symbol = (symbol << 1) | rangeDecoder.decode(bitWithProb: &literalProbs[symbol], pointerData: &pointerData)
}
outWindow.put(byte: (symbol - 0x100).toUInt8())
let byte = (symbol - 0x100).toUInt8()
outWindow.put(byte: byte)
if uncompressedSize > 0 {
out[outIndex] = (symbol - 0x100).toUInt8()
out[outIndex] = byte
outIndex += 1
} else {
out.append((symbol - 0x100).toUInt8())
out.append(byte)
}
}
func decodeDistance(_ len: Int) -> Int {
var lenState = len
if lenState > Constants.numLenToPosStates - 1 {
lenState = Constants.numLenToPosStates - 1
}
let posSlot = posSlotDecoder[lenState].decode(with: rangeDecoder, pointerData: &pointerData)
if posSlot < 4 {
return posSlot
}
let numDirectBits = (posSlot >> 1) - 1
var dist = ((2 | (posSlot & 1)) << numDirectBits)
if posSlot < Constants.endPosModelIndex {
// TODO: Probably incorrect first argument.
dist += bitTreeReverseDecode(probs: &posDecoders, bits: numDirectBits, rangeDecoder: rangeDecoder, pointerData: &pointerData)
} else {
dist += rangeDecoder.decode(directBits: (numDirectBits - Constants.numAlignBits) << Constants.numAlignBits,
pointerData: &pointerData)
dist += alignDecoder.reverseDecode(with: rangeDecoder, pointerData: &pointerData)
}
return dist
}
// Main decoding cycle.
while true {
// If uncompressed size was defined and everything is unpacked then stop.
if uncompressedSize == 0 {
if rangeDecoder.isFinishedOK() {
if rangeDecoder.isFinishedOK {
break
}
}
@@ -354,6 +380,83 @@ public final class LZMA: DecompressionAlgorithm {
state -= 6
}
uncompressedSize -= 1
continue
}
var len: Int
if rangeDecoder.decode(bitWithProb: &isRep[state], pointerData: &pointerData) != 0 {
if uncompressedSize == 0 {
// TODO: throw error
}
if outWindow.isEmpty {
// TODO: throw error
}
if rangeDecoder.decode(bitWithProb: &isRepG0[state], pointerData: &pointerData) == 0 {
if rangeDecoder.decode(bitWithProb: &isRep0Long[(state << Constants.numPosBitsMax) + posState],
pointerData: &pointerData) == 0 {
state = state < 7 ? 9 : 11
let byte = outWindow.byte(at: rep0 + 1)
outWindow.put(byte: byte)
if uncompressedSize > 0 {
out[outIndex] = byte
outIndex += 1
} else {
out.append(byte)
}
uncompressedSize -= 1
continue
}
} else {
let dist: Int
if rangeDecoder.decode(bitWithProb: &isRepG1[state], pointerData: &pointerData) == 0 {
dist = rep1
} else {
if rangeDecoder.decode(bitWithProb: &isRepG2[state], pointerData: &pointerData) == 0 {
dist = rep2
} else {
dist = rep3
rep3 = rep2
}
rep2 = rep1
}
rep1 = rep0
rep0 = dist
}
len = repLenDecoder.decode(with: rangeDecoder, posState: posState, pointerData: &pointerData)
state = state < 7 ? 8 : 11
} else {
rep3 = rep2
rep2 = rep1
rep1 = rep0
len = lenDecoder.decode(with: rangeDecoder, posState: posState, pointerData: &pointerData)
state = state < 7 ? 7 : 10
rep0 = decodeDistance(len)
// Check if finished marker is encoutered.
if rep0 == 0xFFFFFFFF {
if rangeDecoder.isFinishedOK {
break
} else {
// TODO: throw error.
}
}
if uncompressedSize == 0 {
// TODO: throw error.
}
if rep0 >= dictionarySize || !outWindow.check(distance: rep0) {
// TODO: throw error.
}
}
len += Constants.matchMinLen
var isError = false
if uncompressedSize > -1 && uncompressedSize < len {
len = uncompressedSize
isError = true
}
outWindow.copyMatch(at: rep0 + 1, length: len)
uncompressedSize -= len
if isError {
// TODO: throw error.
}
}