Quelle  rle.rs   Sprache: unbekannt

#![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
}