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a21de1d55a
2 changed files with 85 additions and 93 deletions
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@ -64,8 +64,8 @@ type
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DecoderState = object
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buffer: string
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pos, bitCount: int
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bits: uint32
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pos, bitsBuffered: int
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bitBuffer: uint32
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hitEnd: bool
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imageHeight, imageWidth: int
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quantizationTables: array[4, array[64, uint8]]
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@ -89,7 +89,7 @@ template failInvalid(reason = "unable to load") =
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## Throw exception with a reason.
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raise newException(PixieError, "Invalid JPEG, " & reason)
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template clampByte(x): uint8 =
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template clampByte(x: int32): uint8 =
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## Clamp integer into byte range.
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clamp(x, 0, 0xFF).uint8
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@ -143,6 +143,7 @@ proc decodeDQT(state: var DecoderState) =
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proc buildHuffman(huffman: var Huffman, counts: array[16, uint8]) =
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## Builds the huffman data structure.
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block:
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# JPEG spec page 51
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var k: int
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for i in 0.uint8 ..< 16:
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for j in 0.uint8 ..< counts[i]:
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@ -152,14 +153,15 @@ proc buildHuffman(huffman: var Huffman, counts: array[16, uint8]) =
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inc k
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huffman.sizes[k] = 0
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var code, j: int
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# JPEG spec page 52
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var code, k: int
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for i in 1.uint8 .. 16:
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huffman.deltas[i] = j - code
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if huffman.sizes[j] == i:
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while huffman.sizes[j] == i:
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huffman.codes[j] = code.uint16
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huffman.deltas[i] = k - code
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if huffman.sizes[k] == i:
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while huffman.sizes[k] == i:
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huffman.codes[k] = code.uint16
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inc code
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inc j
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inc k
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if code - 1 >= 1 shl i:
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failInvalid()
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huffman.maxCodes[i] = code shl (16 - i)
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@ -169,12 +171,12 @@ proc buildHuffman(huffman: var Huffman, counts: array[16, uint8]) =
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for i in 0 ..< huffman.fast.len:
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huffman.fast[i] = 255
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for i in 0 ..< j:
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for i in 0 ..< k:
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let size = huffman.sizes[i]
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if size <= fastBits:
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let fast = huffman.codes[i].int shl (fastBits - size)
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for k in 0 ..< 1 shl (fastBits - size):
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huffman.fast[fast + k] = i.uint8
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for j in 0 ..< 1 shl (fastBits - size):
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huffman.fast[fast + j] = i.uint8
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proc decodeDHT(state: var DecoderState) =
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## Decode Define Huffman Table
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@ -281,10 +283,7 @@ proc decodeSOF0(state: var DecoderState) =
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component.widthStride = state.numMcuWide * component.yScale * 8
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component.heightStride = state.numMcuHigh * component.xScale * 8
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component.channel = newMask(
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component.widthStride, component.heightStride
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)
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component.channel = newMask(component.widthStride, component.heightStride)
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if state.progressive:
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component.widthCoeff = component.widthStride div 8
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@ -304,8 +303,8 @@ proc decodeSOF2(state: var DecoderState) =
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proc reset(state: var DecoderState) =
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## Rests the decoder state need for reset markers.
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state.bits = 0
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state.bitCount = 0
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state.bitBuffer = 0
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state.bitsBuffered = 0
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for component in 0 ..< state.components.len:
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state.components[component].dcPred = 0
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state.hitEnd = false
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@ -379,60 +378,58 @@ proc decodeSOS(state: var DecoderState) =
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if len != 0:
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failInvalid()
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proc fillBits(state: var DecoderState) =
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proc fillBitBuffer(state: var DecoderState) =
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## When we are low on bits, we need to call this to populate some more.
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while true:
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let b = if state.hitEnd:
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while state.bitsBuffered < 24:
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let b =
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if state.hitEnd:
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0.uint32
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else:
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state.readUint8().uint32
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if b == 0xFF:
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var c = state.readUint8()
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while c == 0xFF: c = state.readUint8()
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while c == 0xFF:
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c = state.readUint8()
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if c != 0:
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dec state.pos
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dec state.pos
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state.pos -= 2
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state.hitEnd = true
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return
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state.bits = state.bits or (b shl (24 - state.bitCount))
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state.bitCount += 8
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if not(state.bitCount <= 24):
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break
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state.bitBuffer = state.bitBuffer or (b shl (24 - state.bitsBuffered))
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state.bitsBuffered += 8
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proc huffmanDecode(state: var DecoderState, tableCurrent, table: int): uint8 =
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## Decode a uint8 from the huffman table.
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if state.bitCount < 16:
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state.fillBits()
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var huffman {.byaddr.} = state.huffmanTables[tableCurrent][table]
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state.fillBitBuffer()
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let
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fastId = (state.bits shr (32 - fastBits)) and ((1 shl fastBits) - 1)
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fast = state.huffmanTables[tableCurrent][table].fast[fastId]
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fastId = (state.bitBuffer shr (32 - fastBits)) and ((1 shl fastBits) - 1)
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fast = huffman.fast[fastId]
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if fast < 255:
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let size = state.huffmanTables[tableCurrent][table].sizes[fast].int
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if size > state.bitCount:
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let size = huffman.sizes[fast].int
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if size > state.bitsBuffered:
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failInvalid()
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state.bits = state.bits shl size
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state.bitCount -= size
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return state.huffmanTables[tableCurrent][table].symbols[fast]
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state.bitBuffer = state.bitBuffer shl size
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state.bitsBuffered -= size
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return huffman.symbols[fast]
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var
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tmp = (state.bits shr 16).int
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tmp = (state.bitBuffer shr 16).int
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i = fastBits + 1
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while i < state.huffmanTables[tableCurrent][table].maxCodes.len:
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if tmp < state.huffmanTables[tableCurrent][table].maxCodes[i]:
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while i < huffman.maxCodes.len:
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if tmp < huffman.maxCodes[i]:
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break
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inc i
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if i == 17 or i > state.bitCount:
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if i == 17 or i > state.bitsBuffered:
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failInvalid()
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let symbolId = (state.bits shr (32 - i)).int +
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state.huffmanTables[tableCurrent][table].deltas[i]
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state.bits = state.bits shl i
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state.bitCount -= i
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return state.huffmanTables[tableCurrent][table].symbols[symbolId]
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let symbolId = (state.bitBuffer shr (32 - i)).int + huffman.deltas[i]
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state.bitBuffer = state.bitBuffer shl i
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state.bitsBuffered -= i
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return huffman.symbols[symbolId]
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template lrot(value: uint32, shift: int): uint32 =
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## Left rotate - used for huffman decoding.
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@ -440,36 +437,36 @@ template lrot(value: uint32, shift: int): uint32 =
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proc getBit(state: var DecoderState): int =
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## Get a single bit.
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if state.bitCount < 1:
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state.fillBits()
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let k = state.bits
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state.bits = state.bits shl 1
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dec state.bitCount
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if state.bitsBuffered < 1:
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state.fillBitBuffer()
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let k = state.bitBuffer
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state.bitBuffer = state.bitBuffer shl 1
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dec state.bitsBuffered
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return (k.int and 0x80000000.int)
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proc getBitsAsSignedInt(state: var DecoderState, n: int): int =
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## Get n number of bits as a signed integer.
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if n notin 0 .. 16:
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failInvalid()
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if state.bitCount < n:
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state.fillBits()
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let sign = cast[int32](state.bits) shr 31
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var k = lrot(state.bits, n)
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state.bits = k and (not bitMasks[n])
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if state.bitsBuffered < n:
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state.fillBitBuffer()
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let sign = cast[int32](state.bitBuffer) shr 31
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var k = lrot(state.bitBuffer, n)
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state.bitBuffer = k and (not bitMasks[n])
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k = k and bitMasks[n]
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state.bitCount -= n
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state.bitsBuffered -= n
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result = k.int + (biases[n] and (not sign))
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proc getBitsAsUnsignedInt(state: var DecoderState, n: int): int =
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## Get n number of bits as a unsigned integer.
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if n notin 0 .. 16:
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failInvalid()
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if state.bitCount < n:
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state.fillBits()
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var k = lrot(state.bits, n)
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state.bits = k and (not bitMasks[n])
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if state.bitsBuffered < n:
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state.fillBitBuffer()
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var k = lrot(state.bitBuffer, n)
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state.bitBuffer = k and (not bitMasks[n])
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k = k and bitMasks[n]
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state.bitCount -= n
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state.bitsBuffered -= n
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return k.int
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proc decodeRegularBlock(
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@ -481,10 +478,11 @@ proc decodeRegularBlock(
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failInvalid()
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let
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diff = if t == 0:
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0
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else:
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state.getBitsAsSignedInt(t)
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diff =
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if t == 0:
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0
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else:
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state.getBitsAsSignedInt(t)
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dc = state.components[component].dcPred + diff
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state.components[component].dcPred = dc
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data[0] = cast[int16](dc)
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@ -768,12 +766,12 @@ proc decodeBlock(state: var DecoderState, comp, row, column: int) =
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else:
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state.decodeRegularBlock(comp, data)
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template checkReset(state: var DecoderState) =
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proc checkReset(state: var DecoderState) =
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## Check if we might have run into a reset marker, then deal with it.
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dec state.todo
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if state.todo <= 0:
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if state.bitCount < 24:
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state.fillBits()
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if state.bitsBuffered < 24:
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state.fillBitBuffer()
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if state.buffer[state.pos] == 0xFF.char:
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if state.buffer[state.pos+1] in {0xD0.char .. 0xD7.char}:
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@ -786,7 +784,6 @@ proc decodeBlocks(state: var DecoderState) =
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## Decodes scan data blocks that follow a SOS block.
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if state.scanComponents == 1:
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# Single component pass.
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let
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comp = state.componentOrder[0]
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w = (state.components[comp].width + 7) shr 3
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@ -814,7 +811,6 @@ proc quantizationAndIDCTPass(state: var DecoderState) =
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let
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w = (state.components[comp].width + 7) shr 3
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h = (state.components[comp].height + 7) shr 3
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for column in 0 ..< h:
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for row in 0 ..< w:
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var data = state.components[comp].blocks[row][column]
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@ -838,13 +834,13 @@ proc magnifyXBy2(mask: Mask): Mask =
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let n = 3 * mask.unsafe[x, y].uint16
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if x == 0:
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result.unsafe[x * 2 + 0, y] = mask.unsafe[x, y]
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result.unsafe[x * 2 + 1, y] = ((n + mask.unsafe[x+1, y].uint16 + 2) div 4).uint8
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result.unsafe[x * 2 + 1, y] = ((n + mask.unsafe[x + 1, y].uint16 + 2) div 4).uint8
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elif x == mask.width - 1:
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result.unsafe[x * 2 + 0, y] = ((n + mask.unsafe[x-1, y].uint16 + 2) div 4).uint8
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result.unsafe[x * 2 + 0, y] = ((n + mask.unsafe[x - 1, y].uint16 + 2) div 4).uint8
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result.unsafe[x * 2 + 1, y] = mask.unsafe[x, y]
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else:
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result.unsafe[x * 2 + 0, y] = ((n + mask.unsafe[x-1, y].uint16) div 4).uint8
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result.unsafe[x * 2 + 1, y] = ((n + mask.unsafe[x+1, y].uint16) div 4).uint8
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result.unsafe[x * 2 + 0, y] = ((n + mask.unsafe[x - 1, y].uint16) div 4).uint8
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result.unsafe[x * 2 + 1, y] = ((n + mask.unsafe[x + 1, y].uint16) div 4).uint8
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proc magnifyYBy2(mask: Mask): Mask =
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## Smooth magnify by power of 2 only in the Y direction.
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@ -854,23 +850,23 @@ proc magnifyYBy2(mask: Mask): Mask =
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let n = 3 * mask.unsafe[x, y].uint16
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if y == 0:
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result.unsafe[x, y * 2 + 0] = mask.unsafe[x, y]
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result.unsafe[x, y * 2 + 1] = ((n + mask.unsafe[x, y+1].uint16 + 2) div 4).uint8
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result.unsafe[x, y * 2 + 1] = ((n + mask.unsafe[x, y + 1].uint16 + 2) div 4).uint8
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elif y == mask.height - 1:
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result.unsafe[x, y * 2 + 0] = ((n + mask.unsafe[x, y-1].uint16 + 2) div 4).uint8
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result.unsafe[x, y * 2 + 0] = ((n + mask.unsafe[x, y - 1].uint16 + 2) div 4).uint8
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result.unsafe[x, y * 2 + 1] = mask.unsafe[x, y]
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else:
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result.unsafe[x, y * 2 + 0] = ((n + mask.unsafe[x, y-1].uint16) div 4).uint8
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result.unsafe[x, y * 2 + 1] = ((n + mask.unsafe[x, y+1].uint16) div 4).uint8
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result.unsafe[x, y * 2 + 0] = ((n + mask.unsafe[x, y - 1].uint16) div 4).uint8
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result.unsafe[x, y * 2 + 1] = ((n + mask.unsafe[x, y + 1].uint16) div 4).uint8
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proc yCbCrToRgbx(py, pcb, pcr: uint8): ColorRGBX =
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## Takes a 3 component yCbCr outputs and populates image.
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template float2Fixed(x: float32): int =
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(x * 4096 + 0.5).int shl 8
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template float2Fixed(x: float32): int32 =
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(x * 4096 + 0.5).int32 shl 8
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let
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yFixed = (py.int shl 20) + (1 shl 19)
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cb = pcb.int - 128
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cr = pcr.int - 128
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yFixed = (py.int32 shl 20) + (1 shl 19)
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cb = pcb.int32 - 128
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cr = pcr.int32 - 128
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var
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r = yFixed + cr * float2Fixed(1.40200)
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g = yFixed +
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@ -882,13 +878,9 @@ proc yCbCrToRgbx(py, pcb, pcr: uint8): ColorRGBX =
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result.b = clampByte(b shr 20)
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result.a = 255
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proc grayScaleToRgbx(gray: uint8): ColorRGBX =
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proc grayScaleToRgbx(gray: uint8): ColorRGBX {.inline.} =
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## Takes a single gray scale component output and populates image.
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let g = gray
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result.r = g
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result.g = g
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result.b = g
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result.a = 255
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rgbx(gray, gray, gray, 255)
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proc buildImage(state: var DecoderState): Image =
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## Takes a jpeg image object and builds a pixie Image from it.
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@ -2,5 +2,5 @@ import benchy, jpegsuite, pixie/fileformats/jpg, strformat
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for file in jpegSuiteFiles:
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let data = readFile(file)
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timeIt &"jpeg {(data.len div 1024)}k decode", 10000:
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timeIt &"jpeg {(data.len div 1024)}k decode":
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discard decodeJpg(data)
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Loading…
Reference in a new issue