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3f2fefb43d
1 changed files with 49 additions and 61 deletions
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@ -79,7 +79,7 @@ type
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componentOrder: seq[int]
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progressive: bool
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restartInterval: int
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todo: int
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todoBeforeRestart: int
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eobRun: int
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when defined(release):
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@ -91,7 +91,11 @@ template failInvalid(reason = "unable to load") =
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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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# clamp(x, 0, 0xFF).uint8
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let
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signBit = (cast[uint32](x) shr 31)
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value = cast[uint32](x) and (signBit - 1)
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min(value, 255).uint8
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proc readUint8(state: var DecoderState): uint8 =
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## Reads a byte from the input stream.
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@ -117,7 +121,7 @@ proc skipChunk(state: var DecoderState) =
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proc decodeDRI(state: var DecoderState) =
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## Decode Define Restart Interval
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var len = state.readUint16be() - 2
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let len = state.readUint16be() - 2
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if len != 2:
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failInvalid("invalid DRI length")
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state.restartInterval = state.readUint16be().int
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@ -212,7 +216,7 @@ proc decodeDHT(state: var DecoderState) =
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proc decodeSOF0(state: var DecoderState) =
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## Decode start of Frame
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var len = state.readUint16be() - 2
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var len = state.readUint16be().int - 2
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let precision = state.readUint8()
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if precision != 8:
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@ -230,6 +234,8 @@ proc decodeSOF0(state: var DecoderState) =
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if numComponents notin {1, 3}:
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failInvalid("unsupported component count, must be 1 or 3")
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len -= 6
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for i in 0 ..< numComponents:
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var component = Component()
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component.id = state.readUint8()
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@ -250,6 +256,8 @@ proc decodeSOF0(state: var DecoderState) =
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component.quantizationTableId = quantizationTableId
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state.components.add(component)
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len -= 3 * numComponents
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for component in state.components.mitems:
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state.maxXScale = max(state.maxXScale, component.xScale)
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state.maxYScale = max(state.maxYScale, component.yScale)
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@ -292,6 +300,9 @@ proc decodeSOF0(state: var DecoderState) =
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component.widthStride * component.heightStride
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)
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if len != 0:
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failInvalid()
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proc decodeSOF1(state: var DecoderState) =
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failInvalid("unsupported extended sequential DCT format")
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@ -302,16 +313,16 @@ proc decodeSOF2(state: var DecoderState) =
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state.progressive = true
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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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## Rests the decoder state need for restart markers.
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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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if state.restartInterval != 0:
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state.todo = state.restartInterval
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state.todoBeforeRestart = state.restartInterval
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else:
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state.todo = 0x7fffffff
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state.todoBeforeRestart = int.high
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state.eobRun = 0
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proc decodeSOS(state: var DecoderState) =
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@ -474,9 +485,8 @@ proc decodeRegularBlock(
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) =
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## Decodes a whole block.
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let t = state.huffmanDecode(0, state.components[component].huffmanDC).int
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if t < 0:
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failInvalid()
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if t > 15:
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failInvalid("bad huffman code")
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let
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diff =
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if t == 0:
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@ -488,7 +498,7 @@ proc decodeRegularBlock(
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data[0] = cast[int16](dc)
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var i = 1
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while true:
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while i < 64:
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let
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rs = state.huffmanDecode(1, state.components[component].huffmanAC)
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s = rs and 15
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@ -499,15 +509,12 @@ proc decodeRegularBlock(
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i += 16
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else:
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i += r.int
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if i notin 0 ..< 64:
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if i >= 64:
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failInvalid()
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let zig = deZigZag[i]
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data[zig] = cast[int16](state.getBitsAsSignedInt(s.int))
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inc i
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if not(i < 64):
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break
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proc decodeProgressiveBlock(
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state: var DecoderState, component: int, data: var array[64, int16]
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) =
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@ -517,18 +524,17 @@ proc decodeProgressiveBlock(
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if state.successiveApproxHigh == 0:
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let t = state.huffmanDecode(0, state.components[component].huffmanDC).int
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if t < 0 or t > 15:
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failInvalid()
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let
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diff = if t != 0:
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state.getBitsAsSignedInt(t)
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else:
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0
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if t > 15:
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failInvalid("bad huffman code")
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let
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diff =
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if t > 0:
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state.getBitsAsSignedInt(t)
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else:
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0
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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 * (1 shl state.successiveApproxLow))
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else:
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if getBit(state) != 0:
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data[0] = cast[int16](data[0] + (1 shl state.successiveApproxLow))
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@ -548,12 +554,9 @@ proc decodeProgressiveContinuationBlock(
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return
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var k = state.spectralStart
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while true:
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while k <= state.spectralEnd:
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let
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rs = state.huffmanDecode(1, state.components[component].huffmanAC)
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if rs < 0:
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failInvalid("bad huffman code")
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let
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s = rs and 15
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r = rs.int shr 4
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if s == 0:
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@ -566,7 +569,7 @@ proc decodeProgressiveContinuationBlock(
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k += 16
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else:
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k += r.int
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if k notin 0 ..< 64:
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if k >= 64:
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failInvalid()
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let zig = deZigZag[k]
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inc k
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@ -574,9 +577,6 @@ proc decodeProgressiveContinuationBlock(
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failInvalid()
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data[zig] = cast[int16](state.getBitsAsSignedInt(s.int) * (1 shl shift))
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if not(k <= state.spectralEnd):
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break
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else:
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var bit = 1 shl state.successiveApproxLow
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@ -593,11 +593,8 @@ proc decodeProgressiveContinuationBlock(
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data[zig] = cast[int16](data[zig] - bit)
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else:
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var k = state.spectralStart
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while true:
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let
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rs = state.huffmanDecode(1, state.components[component].huffmanAC)
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if rs < 0:
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failInvalid("bad huffman code")
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while k <= state.spectralEnd:
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let rs = state.huffmanDecode(1, state.components[component].huffmanAC)
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var
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s = rs.int and 15
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r = rs.int shr 4
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@ -633,9 +630,6 @@ proc decodeProgressiveContinuationBlock(
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break
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dec r
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if not (k <= state.spectralEnd):
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break
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template idct1D(s0, s1, s2, s3, s4, s5, s6, s7: int32) =
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## Inverse discrete cosine transform 1D
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template f2f(x: float32): int32 = (x * 4096 + 0.5).int32
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@ -766,18 +760,18 @@ 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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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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proc checkRestart(state: var DecoderState) =
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## Check if we might have run into a restart marker, then deal with it.
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dec state.todoBeforeRestart
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if state.todoBeforeRestart <= 0:
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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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if state.buffer[state.pos + 1] in {0xD0.char .. 0xD7.char}:
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state.pos += 2
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else:
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failInvalid("did not get expected reset marker")
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failInvalid("did not get expected restart marker")
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state.reset()
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proc decodeBlocks(state: var DecoderState) =
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@ -791,7 +785,7 @@ proc decodeBlocks(state: var DecoderState) =
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for column in 0 ..< h:
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for row in 0 ..< w:
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state.decodeBlock(comp, row, column)
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state.checkReset()
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state.checkRestart()
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else:
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# Interleaved regular component pass.
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for mcuY in 0 ..< state.numMcuHigh:
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@ -803,7 +797,7 @@ proc decodeBlocks(state: var DecoderState) =
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row = (mcuX * state.components[comp].yScale + compX)
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col = (mcuY * state.components[comp].xScale + compY)
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state.decodeBlock(comp, row, col)
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state.checkReset()
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state.checkRestart()
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proc quantizationAndIDCTPass(state: var DecoderState) =
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## Does quantization and IDCT.
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@ -811,16 +805,14 @@ 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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qTableId = state.components[comp].quantizationTableId
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if qTableId.int notin 0 ..< state.quantizationTables.len:
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failInvalid()
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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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var data {.byaddr.} = state.components[comp].blocks[row][column]
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for i in 0 ..< 64:
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let qTableId = state.components[comp].quantizationTableId
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if qTableId.int notin 0 ..< state.quantizationTables.len:
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failInvalid()
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data[i] = cast[int16](data[i] * state.quantizationTables[qTableId][i].int32)
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state.components[comp].idctBlock(
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state.components[comp].widthStride * column * 8 + row * 8,
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data
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@ -909,15 +901,11 @@ proc buildImage(state: var DecoderState): Image =
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cb.unsafe[x, y],
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cr.unsafe[x, y],
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)
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elif state.components.len == 1:
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let
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cy = state.components[0].channel
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let cy = state.components[0].channel
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for y in 0 ..< state.imageHeight:
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for x in 0 ..< state.imageWidth:
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result.unsafe[x, y] = grayScaleToRgbx(
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cy.unsafe[x, y],
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)
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result.unsafe[x, y] = grayScaleToRgbx(cy.unsafe[x, y])
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else:
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failInvalid()
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@ -952,8 +940,8 @@ proc decodeJpeg*(data: string): Image {.raises: [PixieError].} =
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# EOI - End of Image
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break
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of 0xD0 .. 0xD7:
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# Reset markers
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failInvalid("invalid reset marker")
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# Restart markers
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failInvalid("invalid restart marker")
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of 0xDB:
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# Define Quantization Table(s)
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state.decodeDQT()
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