This commit is contained in:
Ryan Oldenburg
parent
ceead0bb36
commit
6e77c401bc
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@ -348,164 +348,165 @@ func deflate*(src: seq[uint8]): seq[uint8] =
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if len > 0:
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b.addBytes(src[pos].unsafeAddr, len.int)
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b.data.setLen(b.data.len)
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else:
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# Deflate using dynamic Huffman tree
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b.data.setLen(b.bytePos)
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return b.data
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let
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(llNumCodes, llLengths, llCodes) = huffmanCodeLengths(
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freqLitLen, 257, maxLitLenCodeLength
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)
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(distNumCodes, distLengths, distCodes) = huffmanCodeLengths(
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freqDist, 2, maxDistCodeLength
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)
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# Deflate using dynamic Huffman tree
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var bitLens = newSeqOfCap[uint8](llNumCodes + distNumCodes)
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for i in 0 ..< llNumCodes:
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bitLens.add(llLengths[i])
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for i in 0 ..< distNumCodes:
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bitLens.add(distLengths[i])
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var
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bitLensRle: seq[uint8]
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bitCount: int
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block construct_binlens_rle:
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var i: int
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while i < bitLens.len:
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var repeatCount: int
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while i + repeatCount + 1 < bitLens.len and
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bitLens[i + repeatCount + 1] == bitLens[i]:
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inc repeatCount
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if bitLens[i] == 0 and repeatCount >= 2:
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inc repeatCount # Initial zero
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if repeatCount <= 10:
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bitLensRle.add([17.uint8, repeatCount.uint8 - 3])
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else:
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repeatCount = min(repeatCount, 138) # Max of 138 zeros for code 18
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bitLensRle.add([18.uint8, repeatCount.uint8 - 11])
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inc(i, repeatCount - 1)
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inc(bitCount, 7)
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elif repeatCount >= 3: # Repeat code for non-zero, must be >= 3 times
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var
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a = repeatCount div 6
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b = repeatCount mod 6
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bitLensRle.add(bitLens[i])
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for j in 0 ..< a:
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bitLensRle.add([16.uint8, 3])
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if b >= 3:
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bitLensRle.add([16.uint8, b.uint8 - 3])
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else:
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dec(repeatCount, b)
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inc(i, repeatCount)
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inc(bitCount, (a + b) * 2)
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else:
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bitLensRle.add(bitLens[i])
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inc i
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inc(bitCount, 7)
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var clFreq = newSeq[int](19)
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block count_cl_frequencies:
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var i: int
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while i < bitLensRle.len:
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inc clFreq[bitLensRle[i]]
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# Skip the number of times codes are repeated
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if bitLensRle[i] >= 16:
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inc i
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inc i
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let (_, clLengths, clCodes) = huffmanCodeLengths(clFreq, clFreq.len, 7)
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var bitLensCodeLen = newSeq[uint8](clFreq.len)
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for i in 0 ..< bitLensCodeLen.len:
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bitLensCodeLen[i] = clLengths[clclOrder[i]]
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while bitLensCodeLen[bitLensCodeLen.high] == 0 and bitLensCodeLen.len > 4:
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bitLensCodeLen.setLen(bitLensCodeLen.len - 1)
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let
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hlit = (llNumCodes - 257).uint8
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hdist = distNumCodes.uint8 - 1
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hclen = bitLensCodeLen.len.uint8 - 4
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# TODO: Improve the b.data.setLens
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b.data.setLen(
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b.data.len +
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(((hclen.int + 4) * 3 + 7) div 8) + # hclen rle
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bitLensRle.len * 2
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let
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(llNumCodes, llLengths, llCodes) = huffmanCodeLengths(
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freqLitLen, 257, maxLitLenCodeLength
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)
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(distNumCodes, distLengths, distCodes) = huffmanCodeLengths(
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freqDist, 2, maxDistCodeLength
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)
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b.addBit(1)
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b.addBits(2, 2)
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var bitLens = newSeqOfCap[uint8](llNumCodes + distNumCodes)
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for i in 0 ..< llNumCodes:
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bitLens.add(llLengths[i])
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for i in 0 ..< distNumCodes:
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bitLens.add(distLengths[i])
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b.addBits(hlit, 5)
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b.addBits(hdist, 5)
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b.addBits(hclen, 4)
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var
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bitLensRle: seq[uint8]
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bitCount: int
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block construct_binlens_rle:
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var i: int
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while i < bitLens.len:
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var repeatCount: int
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while i + repeatCount + 1 < bitLens.len and
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bitLens[i + repeatCount + 1] == bitLens[i]:
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inc repeatCount
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for i in 0.uint8 ..< hclen + 4:
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b.addBits(bitLensCodeLen[i], 3)
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block write_bitlens_rle:
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var i: int
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while i < bitLensRle.len:
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let symbol = bitLensRle[i]
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b.addBits(clCodes[symbol], clLengths[symbol].int)
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inc i
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if symbol == 16:
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b.addBits(bitLensRle[i], 2)
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inc i
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elif symbol == 17:
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b.addBits(bitLensRle[i], 3)
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inc i
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elif symbol == 18:
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b.addBits(bitLensRle[i], 7)
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inc i
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block write_encoded_data:
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var srcPos, encPos: int
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while encPos < encoded.len:
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if (encoded[encPos] and (1 shl 15)) != 0:
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let
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value = encoded[encPos]
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offset = encoded[encPos + 1]
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length = encoded[encPos + 2]
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lengthIndex = (value shr 8) and (uint8.high shr 1)
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distIndex = value and uint8.high
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lengthExtraBits = baseLengthsExtraBits[lengthIndex]
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lengthExtra = length - baseLengths[lengthIndex]
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distExtraBits = baseDistanceExtraBits[distIndex]
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distExtra = offset - baseDistance[distIndex]
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inc(encPos, 3)
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inc(srcPos, length.int)
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if b.data.len < b.bytePos + 6:
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b.data.setLen(b.data.len * 2)
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b.addBits(
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llCodes[lengthIndex + firstLengthCodeIndex],
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llLengths[lengthIndex + firstLengthCodeIndex].int
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)
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b.addBits(lengthExtra, lengthExtraBits)
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b.addBits(distCodes[distIndex], distLengths[distIndex].int)
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b.addBits(distExtra, distExtraBits)
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if bitLens[i] == 0 and repeatCount >= 2:
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inc repeatCount # Initial zero
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if repeatCount <= 10:
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bitLensRle.add([17.uint8, repeatCount.uint8 - 3])
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else:
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let length = encoded[encPos].int
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inc encPos
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repeatCount = min(repeatCount, 138) # Max of 138 zeros for code 18
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bitLensRle.add([18.uint8, repeatCount.uint8 - 11])
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inc(i, repeatCount - 1)
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inc(bitCount, 7)
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elif repeatCount >= 3: # Repeat code for non-zero, must be >= 3 times
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var
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a = repeatCount div 6
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b = repeatCount mod 6
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bitLensRle.add(bitLens[i])
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for j in 0 ..< a:
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bitLensRle.add([16.uint8, 3])
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if b >= 3:
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bitLensRle.add([16.uint8, b.uint8 - 3])
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else:
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dec(repeatCount, b)
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inc(i, repeatCount)
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inc(bitCount, (a + b) * 2)
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else:
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bitLensRle.add(bitLens[i])
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inc i
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inc(bitCount, 7)
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let worstCaseBytesNeeded = (length * maxLitLenCodeLength + 7) div 8
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if b.data.len < b.bytePos + worstCaseBytesNeeded:
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b.data.setLen(max(b.bytePos + worstCaseBytesNeeded, b.data.len * 2))
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var clFreq = newSeq[int](19)
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block count_cl_frequencies:
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var i: int
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while i < bitLensRle.len:
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inc clFreq[bitLensRle[i]]
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# Skip the number of times codes are repeated
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if bitLensRle[i] >= 16:
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inc i
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inc i
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for j in 0 ..< length:
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b.addBits(llCodes[src[srcPos]], llLengths[src[srcPos]].int)
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inc srcPos
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let (_, clLengths, clCodes) = huffmanCodeLengths(clFreq, clFreq.len, 7)
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if llLengths[256] == 0:
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failCompress()
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var bitLensCodeLen = newSeq[uint8](clFreq.len)
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for i in 0 ..< bitLensCodeLen.len:
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bitLensCodeLen[i] = clLengths[clclOrder[i]]
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b.addBits(llCodes[256], llLengths[256].int) # End of block
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while bitLensCodeLen[bitLensCodeLen.high] == 0 and bitLensCodeLen.len > 4:
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bitLensCodeLen.setLen(bitLensCodeLen.len - 1)
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b.skipRemainingBitsInCurrentByte()
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let
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hlit = (llNumCodes - 257).uint8
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hdist = distNumCodes.uint8 - 1
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hclen = bitLensCodeLen.len.uint8 - 4
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# TODO: Improve the b.data.setLens
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b.data.setLen(
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b.data.len +
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(((hclen.int + 4) * 3 + 7) div 8) + # hclen rle
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bitLensRle.len * 2
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)
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b.addBit(1)
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b.addBits(2, 2)
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b.addBits(hlit, 5)
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b.addBits(hdist, 5)
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b.addBits(hclen, 4)
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for i in 0.uint8 ..< hclen + 4:
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b.addBits(bitLensCodeLen[i], 3)
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block write_bitlens_rle:
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var i: int
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while i < bitLensRle.len:
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let symbol = bitLensRle[i]
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b.addBits(clCodes[symbol], clLengths[symbol].int)
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inc i
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if symbol == 16:
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b.addBits(bitLensRle[i], 2)
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inc i
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elif symbol == 17:
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b.addBits(bitLensRle[i], 3)
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inc i
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elif symbol == 18:
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b.addBits(bitLensRle[i], 7)
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inc i
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block write_encoded_data:
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var srcPos, encPos: int
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while encPos < encoded.len:
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if (encoded[encPos] and (1 shl 15)) != 0:
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let
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value = encoded[encPos]
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offset = encoded[encPos + 1]
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length = encoded[encPos + 2]
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lengthIndex = (value shr 8) and (uint8.high shr 1)
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distIndex = value and uint8.high
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lengthExtraBits = baseLengthsExtraBits[lengthIndex]
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lengthExtra = length - baseLengths[lengthIndex]
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distExtraBits = baseDistanceExtraBits[distIndex]
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distExtra = offset - baseDistance[distIndex]
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inc(encPos, 3)
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inc(srcPos, length.int)
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if b.data.len < b.bytePos + 6:
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b.data.setLen(b.data.len * 2)
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b.addBits(
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llCodes[lengthIndex + firstLengthCodeIndex],
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llLengths[lengthIndex + firstLengthCodeIndex].int
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)
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b.addBits(lengthExtra, lengthExtraBits)
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b.addBits(distCodes[distIndex], distLengths[distIndex].int)
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b.addBits(distExtra, distExtraBits)
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else:
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let length = encoded[encPos].int
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inc encPos
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let worstCaseBytesNeeded = (length * maxLitLenCodeLength + 7) div 8
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if b.data.len < b.bytePos + worstCaseBytesNeeded:
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b.data.setLen(max(b.bytePos + worstCaseBytesNeeded, b.data.len * 2))
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for j in 0 ..< length:
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b.addBits(llCodes[src[srcPos]], llLengths[src[srcPos]].int)
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inc srcPos
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if llLengths[256] == 0:
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failCompress()
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b.addBits(llCodes[256], llLengths[256].int) # End of block
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b.skipRemainingBitsInCurrentByte()
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b.data.setLen(b.bytePos)
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b.data
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