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This commit is contained in:
Ryan Oldenburg 2022-05-13 00:08:03 -05:00
parent 68b9d63ecd
commit 01fe732608
1 changed files with 3 additions and 4 deletions
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7
src/pixie/fileformats/jpeg.nim
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@ -399,11 +399,10 @@ proc fillBitBuffer(state: var DecoderState) =
proc huffmanDecode(state: var DecoderState, tableCurrent, table: int): uint8 = proc huffmanDecode(state: var DecoderState, tableCurrent, table: int): uint8 =
## Decode a uint8 from the huffman table. ## Decode a uint8 from the huffman table.
if state.bitsBuffered < 16:
state.fillBitBuffer()
var huffman {.byaddr.} = state.huffmanTables[tableCurrent][table] var huffman {.byaddr.} = state.huffmanTables[tableCurrent][table]
state.fillBitBuffer()
let let
fastId = (state.bitBuffer shr (32 - fastBits)) and ((1 shl fastBits) - 1) fastId = (state.bitBuffer shr (32 - fastBits)) and ((1 shl fastBits) - 1)
fast = huffman.fast[fastId] fast = huffman.fast[fastId]
@ -430,7 +429,7 @@ proc huffmanDecode(state: var DecoderState, tableCurrent, table: int): uint8 =
let symbolId = (state.bitBuffer shr (32 - i)).int + huffman.deltas[i] let symbolId = (state.bitBuffer shr (32 - i)).int + huffman.deltas[i]
state.bitBuffer = state.bitBuffer shl i state.bitBuffer = state.bitBuffer shl i
state.bitsBuffered -= i state.bitsBuffered -= i
huffman.symbols[symbolId] return huffman.symbols[symbolId]
template lrot(value: uint32, shift: int): uint32 = template lrot(value: uint32, shift: int): uint32 =
## Left rotate - used for huffman decoding. ## Left rotate - used for huffman decoding.