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Apparently, I've missed extraDistanceBits array and was reading a value from wrong array. This was fixed.

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This commit is contained in:
Timofey Solomko
2016-10-28 21:02:31 +03:00
parent 8389ac4673
commit c7a66d58ea
2 changed files with 21 additions and 7 deletions
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Sources/Deflate.swift
+11 -7
View File
@@ -223,23 +223,27 @@ public class Deflate {
index += shift + addBits >= 8 ? 1 : 0
shift = shift + addBits >= 8 ? shift - (8 - addBits) : shift + addBits
let end = (index, shift)
let extraLength = convertToInt(uint8Array: data.bits(from: start, to: end))
var length = HuffmanTable.Constants.lengthBase[symbol - 257] + extraLength
var length = HuffmanTable.Constants.lengthBase[symbol - 257] +
convertToInt(uint8Array: data.bits(from: start, to: end))
let newSymbolTuple = mainDistances.findNextSymbol(in: Data(data[index...index + 1]),
withShift: shift)
let newSymbol = newSymbolTuple.symbol
guard newSymbol != -1 else { throw DeflateError.HuffmanTableError }
index += newSymbolTuple.addToIndex
shift = newSymbolTuple.newShift
if newSymbol >= 0 && newSymbol <= 29 {
let start = (index, shift)
index += shift + newSymbol >= 8 ? 1 : 0
shift = shift + newSymbol >= 8 ? shift - (8 - newSymbol) : shift + newSymbol
let extraDistance = HuffmanTable.Constants.extraDistanceBits(n: newSymbol)
guard extraDistance != -1 else { throw DeflateError.HuffmanTableError }
index += shift + extraDistance >= 8 ? 1 : 0
shift = shift + extraDistance >= 8 ?
shift - (8 - extraDistance) : shift + extraDistance
let end = (index, shift)
let dstBase = HuffmanTable.Constants.distanceBase[newSymbol]
let distance = dstBase +
let distance = HuffmanTable.Constants.distanceBase[newSymbol] +
convertToInt(uint8Array: data.bits(from: start, to: end))
print("distance: \(distance), dstBase: \(dstBase), newSymbol: \(newSymbol)")
while length > distance {
out.append(contentsOf: Array(out[out.count - distance..<out.count]))
length -= distance
Sources/HuffmanTable.swift
+10
View File
@@ -34,6 +34,16 @@ class HuffmanTable: CustomStringConvertible {
}
}
static func extraDistanceBits(n: Int) -> Int {
if n >= 0 && n <= 1 {
return 0
} else if n >= 2 && n <= 29 {
return (n >> 1) - 1
} else {
return -1
}
}
}
var lengths: [HuffmanLength]