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Optimize encode code

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lifegpc
2025-07-04 14:10:06 +08:00
parent 4141f361e3
commit 99c0d657fc
2 changed files with 50 additions and 30 deletions
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62
src/scripts/bgi/archive/dsc.rs
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@@ -350,34 +350,72 @@ impl<'a, T: Write + Seek> DscEncoder<'a, T> {
// LZSS compression
let mut ops = vec![];
let mut pos = 0;
const MIN_LEN: usize = 2;
const MAX_LEN: usize = 257;
const WINDOW_SIZE: usize = 4097;
let mut head: Vec<i32> = vec![-1; 1 << 16];
let mut prev: Vec<i32> = vec![-1; data.len()];
while pos < data.len() {
let max_len = (data.len() - pos).min(MAX_LEN);
let mut best_len = 0;
let mut best_offset = 0;
let max_len = (data.len() - pos).min(257);
if max_len >= 2 {
let search_start = if pos > 4097 { pos - 4097 } else { 0 };
let lookbehind = &data[search_start..pos];
for len in (2..=max_len).rev() {
if let Some(found_idx) = lookbehind.rfind(&data[pos..pos + len]) {
let offset = lookbehind.len() - found_idx;
if offset >= 2 {
best_len = len;
best_offset = offset;
break;
if max_len >= MIN_LEN {
let limit = pos.saturating_sub(WINDOW_SIZE);
let key = (data[pos] as u16) << 8 | data[pos + 1] as u16;
let mut match_pos_i32 = head[key as usize];
while match_pos_i32 != -1 {
let match_pos = match_pos_i32 as usize;
if match_pos < limit {
break;
}
if data.get(match_pos + best_len) == data.get(pos + best_len) {
let mut current_len = 0;
for i in 0..max_len {
if data.get(pos + i) != data.get(match_pos + i) {
break;
}
current_len += 1;
}
if current_len > best_len {
best_len = current_len;
best_offset = pos - match_pos;
if best_len >= max_len {
break;
}
}
}
match_pos_i32 = prev[match_pos];
}
}
if best_len >= 2 {
if best_len >= MIN_LEN && best_offset >= 2 {
ops.push(LzssOp::Match {
len: best_len as u16,
offset: best_offset as u16,
});
for i in 0..best_len {
if pos + i + 1 < data.len() {
let key = (data[pos + i] as u16) << 8 | data[pos + i + 1] as u16;
let current_pos = pos + i;
prev[current_pos] = head[key as usize];
head[key as usize] = current_pos as i32;
}
}
pos += best_len;
} else {
ops.push(LzssOp::Literal(data[pos]));
if pos + 1 < data.len() {
let key = (data[pos] as u16) << 8 | data[pos + 1] as u16;
prev[pos] = head[key as usize];
head[key as usize] = pos as i32;
}
pos += 1;
}
}