rename
This commit is contained in:
Ryan Oldenburg
parent
f03b2e2ef3
commit
6cfb98553c
|
|
@ -64,8 +64,8 @@ type
|
|||
|
||||
DecoderState = object
|
||||
buffer: string
|
||||
pos, bitCount: int
|
||||
bits: uint32
|
||||
pos, bitsBuffered: int
|
||||
bitBuffer: uint32
|
||||
hitEnd: bool
|
||||
imageHeight, imageWidth: int
|
||||
quantizationTables: array[4, array[64, uint8]]
|
||||
|
|
@ -306,8 +306,8 @@ proc decodeSOF2(state: var DecoderState) =
|
|||
|
||||
proc reset(state: var DecoderState) =
|
||||
## Rests the decoder state need for reset markers.
|
||||
state.bits = 0
|
||||
state.bitCount = 0
|
||||
state.bitBuffer = 0
|
||||
state.bitsBuffered = 0
|
||||
for component in 0 ..< state.components.len:
|
||||
state.components[component].dcPred = 0
|
||||
state.hitEnd = false
|
||||
|
|
@ -381,7 +381,7 @@ proc decodeSOS(state: var DecoderState) =
|
|||
if len != 0:
|
||||
failInvalid()
|
||||
|
||||
proc fillBits(state: var DecoderState) =
|
||||
proc fillBitBuffer(state: var DecoderState) =
|
||||
## When we are low on bits, we need to call this to populate some more.
|
||||
while true:
|
||||
let b = if state.hitEnd:
|
||||
|
|
@ -396,45 +396,45 @@ proc fillBits(state: var DecoderState) =
|
|||
dec state.pos
|
||||
state.hitEnd = true
|
||||
return
|
||||
state.bits = state.bits or (b shl (24 - state.bitCount))
|
||||
state.bitCount += 8
|
||||
state.bitBuffer = state.bitBuffer or (b shl (24 - state.bitsBuffered))
|
||||
state.bitsBuffered += 8
|
||||
|
||||
if not(state.bitCount <= 24):
|
||||
if not(state.bitsBuffered <= 24):
|
||||
break
|
||||
|
||||
proc huffmanDecode(state: var DecoderState, tableCurrent, table: int): uint8 =
|
||||
## Decode a uint8 from the huffman table.
|
||||
if state.bitCount < 16:
|
||||
state.fillBits()
|
||||
if state.bitsBuffered < 16:
|
||||
state.fillBitBuffer()
|
||||
|
||||
var huffman {.byaddr.} = state.huffmanTables[tableCurrent][table]
|
||||
|
||||
let
|
||||
fastId = (state.bits shr (32 - fastBits)) and ((1 shl fastBits) - 1)
|
||||
fastId = (state.bitBuffer shr (32 - fastBits)) and ((1 shl fastBits) - 1)
|
||||
fast = huffman.fast[fastId]
|
||||
|
||||
if fast < 255:
|
||||
let size = huffman.sizes[fast].int
|
||||
if size > state.bitCount:
|
||||
if size > state.bitsBuffered:
|
||||
failInvalid()
|
||||
state.bits = state.bits shl size
|
||||
state.bitCount -= size
|
||||
state.bitBuffer = state.bitBuffer shl size
|
||||
state.bitsBuffered -= size
|
||||
return huffman.symbols[fast]
|
||||
|
||||
var
|
||||
tmp = (state.bits shr 16).int
|
||||
tmp = (state.bitBuffer shr 16).int
|
||||
i = fastBits + 1
|
||||
while i < huffman.maxCodes.len:
|
||||
if tmp < huffman.maxCodes[i]:
|
||||
break
|
||||
inc i
|
||||
|
||||
if i == 17 or i > state.bitCount:
|
||||
if i == 17 or i > state.bitsBuffered:
|
||||
failInvalid()
|
||||
|
||||
let symbolId = (state.bits shr (32 - i)).int + huffman.deltas[i]
|
||||
state.bits = state.bits shl i
|
||||
state.bitCount -= i
|
||||
let symbolId = (state.bitBuffer shr (32 - i)).int + huffman.deltas[i]
|
||||
state.bitBuffer = state.bitBuffer shl i
|
||||
state.bitsBuffered -= i
|
||||
huffman.symbols[symbolId]
|
||||
|
||||
template lrot(value: uint32, shift: int): uint32 =
|
||||
|
|
@ -443,36 +443,36 @@ template lrot(value: uint32, shift: int): uint32 =
|
|||
|
||||
proc getBit(state: var DecoderState): int =
|
||||
## Get a single bit.
|
||||
if state.bitCount < 1:
|
||||
state.fillBits()
|
||||
let k = state.bits
|
||||
state.bits = state.bits shl 1
|
||||
dec state.bitCount
|
||||
if state.bitsBuffered < 1:
|
||||
state.fillBitBuffer()
|
||||
let k = state.bitBuffer
|
||||
state.bitBuffer = state.bitBuffer shl 1
|
||||
dec state.bitsBuffered
|
||||
return (k.int and 0x80000000.int)
|
||||
|
||||
proc getBitsAsSignedInt(state: var DecoderState, n: int): int =
|
||||
## Get n number of bits as a signed integer.
|
||||
if n notin 0 .. 16:
|
||||
failInvalid()
|
||||
if state.bitCount < n:
|
||||
state.fillBits()
|
||||
let sign = cast[int32](state.bits) shr 31
|
||||
var k = lrot(state.bits, n)
|
||||
state.bits = k and (not bitMasks[n])
|
||||
if state.bitsBuffered < n:
|
||||
state.fillBitBuffer()
|
||||
let sign = cast[int32](state.bitBuffer) shr 31
|
||||
var k = lrot(state.bitBuffer, n)
|
||||
state.bitBuffer = k and (not bitMasks[n])
|
||||
k = k and bitMasks[n]
|
||||
state.bitCount -= n
|
||||
state.bitsBuffered -= n
|
||||
result = k.int + (biases[n] and (not sign))
|
||||
|
||||
proc getBitsAsUnsignedInt(state: var DecoderState, n: int): int =
|
||||
## Get n number of bits as a unsigned integer.
|
||||
if n notin 0 .. 16:
|
||||
failInvalid()
|
||||
if state.bitCount < n:
|
||||
state.fillBits()
|
||||
var k = lrot(state.bits, n)
|
||||
state.bits = k and (not bitMasks[n])
|
||||
if state.bitsBuffered < n:
|
||||
state.fillBitBuffer()
|
||||
var k = lrot(state.bitBuffer, n)
|
||||
state.bitBuffer = k and (not bitMasks[n])
|
||||
k = k and bitMasks[n]
|
||||
state.bitCount -= n
|
||||
state.bitsBuffered -= n
|
||||
return k.int
|
||||
|
||||
proc decodeRegularBlock(
|
||||
|
|
@ -775,8 +775,8 @@ proc checkReset(state: var DecoderState) =
|
|||
## Check if we might have run into a reset marker, then deal with it.
|
||||
dec state.todo
|
||||
if state.todo <= 0:
|
||||
if state.bitCount < 24:
|
||||
state.fillBits()
|
||||
if state.bitsBuffered < 24:
|
||||
state.fillBitBuffer()
|
||||
|
||||
if state.buffer[state.pos] == 0xFF.char:
|
||||
if state.buffer[state.pos+1] in {0xD0.char .. 0xD7.char}:
|
||||
|
|
|
|||
Loading…
Reference in a new issue