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Merge pull request #352 from fintelia/remove-goto
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Remove goto! macro
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@fintelia
fintelia authored Aug 11, 2022
2 parents cfab4ee + 80dbccb commit 536f76f
Showing 1 changed file with 47 additions and 70 deletions.
117 changes: 47 additions & 70 deletions src/decoder/stream.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -500,25 +500,6 @@ impl StreamingDecoder {
) -> Result<(usize, Decoded), DecodingError> {
use self::State::*;

macro_rules! goto (
($n:expr, $state:expr) => ({
self.state = Some($state);
Ok(($n, Decoded::Nothing))
});
($state:expr) => ({
self.state = Some($state);
Ok((1, Decoded::Nothing))
});
($n:expr, $state:expr, emit $res:expr) => ({
self.state = Some($state);
Ok(($n, $res))
});
($state:expr, emit $res:expr) => ({
self.state = Some($state);
Ok((1, $res))
})
);

let current_byte = buf[0];

// Driver should ensure that state is never None
Expand All @@ -527,12 +508,14 @@ impl StreamingDecoder {
match state {
Signature(i, mut signature) if i < 7 => {
signature[i as usize] = current_byte;
goto!(Signature(i + 1, signature))
self.state = Some(Signature(i + 1, signature));
Ok((1, Decoded::Nothing))
}
Signature(_, signature)
if signature == [137, 80, 78, 71, 13, 10, 26] && current_byte == 10 =>
{
goto!(U32(U32Value::Length))
self.state = Some(U32(U32Value::Length));
Ok((1, Decoded::Nothing))
}
Signature(..) => Err(DecodingError::Format(
FormatErrorInner::InvalidSignature.into(),
Expand All @@ -541,7 +524,10 @@ impl StreamingDecoder {
use self::U32Value::*;
val |= u32::from(current_byte);
match type_ {
Length => goto!(U32(Type(val))),
Length => {
self.state = Some(U32(Type(val)));
Ok((1, Decoded::Nothing))
}
Type(length) => {
let type_str = ChunkType([
(val >> 24) as u8,
Expand All @@ -556,34 +542,27 @@ impl StreamingDecoder {
self.current_chunk.type_ = type_str;
self.inflater.finish_compressed_chunks(image_data)?;
self.inflater.reset();
return goto!(
0,
U32Byte3(Type(length), val & !0xff),
emit Decoded::ImageDataFlushed
);
self.state = Some(U32Byte3(Type(length), val & !0xff));
return Ok((0, Decoded::ImageDataFlushed));
}
self.current_chunk.type_ = type_str;
self.current_chunk.crc.reset();
self.current_chunk.crc.update(&type_str.0);
self.current_chunk.remaining = length;
self.apng_seq_handled = false;
self.current_chunk.raw_bytes.clear();
goto!(
ReadChunk(type_str),
emit Decoded::ChunkBegin(length, type_str)
)
self.state = Some(ReadChunk(type_str));
Ok((1, Decoded::ChunkBegin(length, type_str)))
}
Crc(type_str) => {
let sum = self.current_chunk.crc.clone().finalize();
if CHECKSUM_DISABLED || val == sum {
goto!(
State::U32(U32Value::Length),
emit if type_str == IEND {
Decoded::ImageEnd
} else {
Decoded::ChunkComplete(val, type_str)
}
)
self.state = Some(State::U32(U32Value::Length));
if type_str == IEND {
Ok((1, Decoded::ImageEnd))
} else {
Ok((1, Decoded::ChunkComplete(val, type_str)))
}
} else {
Err(DecodingError::Format(
FormatErrorInner::CrcMismatch {
Expand All @@ -598,18 +577,24 @@ impl StreamingDecoder {
}
}
}
U32Byte2(type_, val) => goto!(U32Byte3(type_, val | u32::from(current_byte) << 8)),
U32Byte1(type_, val) => goto!(U32Byte2(type_, val | u32::from(current_byte) << 16)),
U32(type_) => goto!(U32Byte1(type_, u32::from(current_byte) << 24)),
U32Byte2(type_, val) => {
self.state = Some(U32Byte3(type_, val | u32::from(current_byte) << 8));
Ok((1, Decoded::Nothing))
}
U32Byte1(type_, val) => {
self.state = Some(U32Byte2(type_, val | u32::from(current_byte) << 16));
Ok((1, Decoded::Nothing))
}
U32(type_) => {
self.state = Some(U32Byte1(type_, u32::from(current_byte) << 24));
Ok((1, Decoded::Nothing))
}
PartialChunk(type_str) => {
match type_str {
IDAT => {
self.have_idat = true;
goto!(
0,
DecodeData(type_str, 0),
emit Decoded::PartialChunk(type_str)
)
self.state = Some(DecodeData(type_str, 0));
Ok((0, Decoded::PartialChunk(type_str)))
}
chunk::fdAT => {
let data_start;
Expand Down Expand Up @@ -637,11 +622,8 @@ impl StreamingDecoder {
FormatErrorInner::MissingFctl.into(),
));
}
goto!(
0,
DecodeData(type_str, data_start),
emit Decoded::PartialChunk(type_str)
)
self.state = Some(DecodeData(type_str, data_start));
Ok((0, Decoded::PartialChunk(type_str)))
}
// Handle other chunks
_ => {
Expand All @@ -653,10 +635,8 @@ impl StreamingDecoder {
// We need it fully before parsing.
self.reserve_current_chunk()?;

goto!(
0, ReadChunk(type_str),
emit Decoded::PartialChunk(type_str)
)
self.state = Some(ReadChunk(type_str));
Ok((0, Decoded::PartialChunk(type_str)))
}
}
}
Expand All @@ -665,7 +645,8 @@ impl StreamingDecoder {
// The _previous_ event wanted to return the contents of raw_bytes, and let the
// caller consume it,
if self.current_chunk.remaining == 0 {
goto!(0, U32(U32Value::Crc(type_str)))
self.state = Some(U32(U32Value::Crc(type_str)));
Ok((0, Decoded::Nothing))
} else {
let ChunkState {
crc,
Expand All @@ -678,18 +659,20 @@ impl StreamingDecoder {
let bytes_avail = min(buf.len(), buf_avail);
let n = min(*remaining, bytes_avail as u32);
if buf_avail == 0 {
goto!(0, PartialChunk(type_str))
self.state = Some(PartialChunk(type_str));
Ok((0, Decoded::Nothing))
} else {
let buf = &buf[..n as usize];
crc.update(buf);
raw_bytes.extend_from_slice(buf);

*remaining -= n;
if *remaining == 0 {
goto!(n as usize, PartialChunk(type_str))
self.state = Some(PartialChunk(type_str));
} else {
goto!(n as usize, ReadChunk(type_str))
self.state = Some(ReadChunk(type_str));
}
Ok((n as usize, Decoded::Nothing))
}
}
}
Expand All @@ -700,17 +683,11 @@ impl StreamingDecoder {
n += c;
if n == chunk_len && c == 0 {
self.current_chunk.raw_bytes.clear();
goto!(
0,
ReadChunk(type_str),
emit Decoded::ImageData
)
self.state = Some(ReadChunk(type_str));
Ok((0, Decoded::ImageData))
} else {
goto!(
0,
DecodeData(type_str, n),
emit Decoded::ImageData
)
self.state = Some(DecodeData(type_str, n));
Ok((0, Decoded::ImageData))
}
}
}
Expand Down

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