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refactor: remove vec alloc in format function, extending out vec instead

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YK 2024-07-11 16:43:02 +03:00
parent 8e79a7954a
commit 5b2d912cf8
3 changed files with 18 additions and 14 deletions
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1
Cargo.lock generated
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@ -744,6 +744,7 @@ dependencies = [
name = "qoi2"
version = "0.1.0"
dependencies = [
"anyhow",
"bytemuck",
"imageproc",
"itertools 0.13.0",

1
Cargo.toml
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@ -4,6 +4,7 @@ version = "0.1.0"
edition = "2021"
[dependencies]
anyhow = "1.0.86"
bytemuck = "1.16.1"
imageproc = "0.25.0"
itertools = "0.13.0"

30
src/encoder.rs
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@ -1,11 +1,12 @@
use std::mem::discriminant;
use itertools::Itertools;
use crate::common::*;
// @TODO replace Options with custom Errors
impl Ops {
// @TODO don't alloc here, get a mut reference and extend here
fn format (self) -> Vec<u8> {
fn write_encoded (self, buf: &mut Vec<u8>) {
// cast_diff
let cd = |diff: i8| cast_with_bias(diff, 2);
// cast_luma_green
@ -14,13 +15,13 @@ impl Ops {
let clrb = |diff: i8| cast_with_bias(diff, 8);
match self {
Ops::Nop => vec![],
Ops::Rgb([r, g, b]) => vec![254, r, g, b],
Ops::Rgba([r, g, b, a]) => vec![255, r, g, b, a],
Ops::Index(idx) => vec![idx as u8],
Ops::Run(len) => vec![(3 << 6) | (len - 1)],
Ops::Diff([dr, dg, db]) => vec![(1 << 6) | ((cd(dr) << 4) | (cd(dg) << 2) | cd(db)) ],
Ops::Luma([dr, dg, db]) => vec![(2 << 6) | clg(dg), (clrb(dr) << 4) | clrb(db)],
Ops::Nop => (),
Ops::Rgb([r, g, b]) => buf.extend_from_slice(&[254, r, g, b]),
Ops::Rgba([r, g, b, a]) => buf.extend_from_slice(&[255, r, g, b, a]),
Ops::Index(idx) => buf.push(idx as u8),
Ops::Run(len) => buf.push((3 << 6) | (len - 1)),
Ops::Diff([dr, dg, db]) => buf.push((1 << 6) | ((cd(dr) << 4) | (cd(dg) << 2) | cd(db))),
Ops::Luma([dr, dg, db]) => buf.extend_from_slice(&[(2 << 6) | clg(dg), (clrb(dr) << 4) | clrb(db)]),
}
}
}
@ -57,8 +58,9 @@ fn encode_body (header: Header, data: &[u8]) -> Option<Vec<u8>> {
Ops::Run(run) if run < 62 => cur = Ops::Run(run + 1),
// if run is full, commit it to out vec, and start a new one
Ops::Run(run) if run >= 62 => {
cur = Ops::Run(62); // clamp for safety;
cur.write_encoded(&mut out);
cur = Ops::Run(1);
out.extend_from_slice(&Ops::Run(62).format());
},
// otherwise (default case, when encountering a match for the first time) start a run
_ => cur = Ops::Run(1),
@ -66,19 +68,19 @@ fn encode_body (header: Header, data: &[u8]) -> Option<Vec<u8>> {
} else {
// if current Op is Run (meaning we need to and it since there's no match)
if discriminant(&cur) == discriminant(&Ops::Run(0)) {
out.extend_from_slice(&cur.format());
cur.write_encoded(&mut out);
}
let hash = hash(rgba);
// INDEX -> DIFF -> LUMA -> RGB(A)
if known[hash] == rgba {
cur = Ops::Index(hash);
} else if let Some(ops) = diff_ops([r, g, b, a], [last[0], last[1], last[2], last[3]]) {
} else if let Some(ops) = diff_ops([r, g, b, a], last) {
cur = ops;
} else {
cur = header.channels.ops_color(&rgba[..header.channels.num()])?;
}
out.extend_from_slice(&cur.format());
cur.write_encoded(&mut out);
last = rgba;
known[hash] = rgba;
}
@ -86,7 +88,7 @@ fn encode_body (header: Header, data: &[u8]) -> Option<Vec<u8>> {
// if an image buffer ends with a run, flush it as well
if discriminant(&cur) == discriminant(&Ops::Run(0)) {
out.extend_from_slice(&cur.format());
cur.write_encoded(&mut out);
}
Some(out)