Revision control
Copy as Markdown
Other Tools
#![forbid(unsafe_code)]
use crate::{
deflate::{
compare256::compare256_rle_slice, fill_window, BlockState, DeflateStream, MIN_LOOKAHEAD,
STD_MAX_MATCH, STD_MIN_MATCH,
},
flush_block, DeflateFlush,
};
pub fn deflate_rle(stream: &mut DeflateStream, flush: DeflateFlush) -> BlockState {
let mut match_len = 0;
let mut bflush;
loop {
// Make sure that we always have enough lookahead, except
// at the end of the input file. We need STD_MAX_MATCH bytes
// for the next match, plus WANT_MIN_MATCH bytes to insert the
// string following the next match.
if stream.state.lookahead < MIN_LOOKAHEAD {
fill_window(stream);
if stream.state.lookahead < MIN_LOOKAHEAD && flush == DeflateFlush::NoFlush {
return BlockState::NeedMore;
}
if stream.state.lookahead == 0 {
break; /* flush the current block */
}
}
/* See how many times the previous byte repeats */
let state = &mut stream.state;
if state.lookahead >= STD_MIN_MATCH && state.strstart > 0 {
let scan = &state.window.filled()[state.strstart - 1..][..3 + 256];
{
if scan[0] == scan[1] && scan[1] == scan[2] {
match_len = compare256_rle_slice(scan[0], &scan[3..]) + 2;
match_len = Ord::min(match_len, state.lookahead);
match_len = Ord::min(match_len, STD_MAX_MATCH);
}
}
assert!(
state.strstart - 1 + match_len <= state.window_size - 1,
"wild scan"
);
}
/* Emit match if have run of STD_MIN_MATCH or longer, else emit literal */
if match_len >= STD_MIN_MATCH {
// check_match(s, s->strstart, s->strstart - 1, match_len);
bflush = state.tally_dist(1, match_len - STD_MIN_MATCH);
state.lookahead -= match_len;
state.strstart += match_len;
match_len = 0;
} else {
/* No match, output a literal byte */
let lc = state.window.filled()[state.strstart];
bflush = state.tally_lit(lc);
state.lookahead -= 1;
state.strstart += 1;
}
if bflush {
flush_block!(stream, false);
}
}
stream.state.insert = 0;
if flush == DeflateFlush::Finish {
flush_block!(stream, true);
return BlockState::FinishDone;
}
if !stream.state.sym_buf.is_empty() {
flush_block!(stream, false);
}
BlockState::BlockDone
}