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getBits

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This commit is contained in:
Ryan Oldenburg 2022-05-25 22:17:41 -05:00
parent 7b1cd09cd3
commit b1d111d1bf
1 changed files with 5 additions and 6 deletions
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11
src/pixie/fileformats/jpeg.nim
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@ -547,17 +547,16 @@ proc getBitsAsSignedInt(state: var DecoderState, n: int): int =
state.bitsBuffered -= n
result = k.int + (biases[n] and (not sign))
proc getBitsAsUnsignedInt(state: var DecoderState, n: int): int =
proc getBits(state: var DecoderState, n: int): int =
## Get n number of bits as a unsigned integer.
if n notin 0 .. 16:
failInvalid()
if state.bitsBuffered < n:
state.fillBitBuffer()
var k = lrot(state.bitBuffer, n)
let k = lrot(state.bitBuffer, n)
state.bitBuffer = k and (not bitMasks[n])
k = k and bitMasks[n]
result = (k and bitMasks[n]).int
state.bitsBuffered -= n
return k.int
proc decodeRegularBlock(
state: var DecoderState, component: int, data: var array[64, int16]
@ -642,7 +641,7 @@ proc decodeProgressiveContinuationBlock(
if r < 15:
state.eobRun = 1 shl r
if r != 0:
state.eobRun += state.getBitsAsUnsignedInt(r)
state.eobRun += state.getBits(r)
dec state.eobRun
break
k += 16
@ -681,7 +680,7 @@ proc decodeProgressiveContinuationBlock(
if r < 15:
state.eobRun = (1 shl r) - 1
if r != 0:
state.eobRun += state.getBitsAsUnsignedInt(r)
state.eobRun += state.getBits(r)
r = 64 # force end of block
else:
discard