deflate_huff.c

/* deflate_huff.c -- compress data using huffman encoding only strategy
 *
 * Copyright (C) 1995-2024 Jean-loup Gailly and Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

#include "zbuild.h"
#include "deflate.h"
#include "deflate_p.h"
#include "functable.h"

/* ===========================================================================
 * For Z_HUFFMAN_ONLY, do not look for matches.  Do not maintain a hash table.
 * (It will be regenerated if this run of deflate switches away from Huffman.)
 */
Z_INTERNAL block_state deflate_huff(deflate_state *s, int flush) {
    int bflush = 0;         /* set if current block must be flushed */

    for (;;) {
        /* Make sure that we have a literal to write. */
        if (s->lookahead == 0) {
            PREFIX(fill_window)(s);
            if (s->lookahead == 0) {
                if (flush == Z_NO_FLUSH)
                    return need_more;
                break;      /* flush the current block */
            }
        }

        /* Output a literal byte */
        bflush = zng_tr_tally_lit(s, s->window[s->strstart]);
        s->lookahead--;
        s->strstart++;
        if (bflush)
            FLUSH_BLOCK(s, 0);
    }
    s->insert = 0;
    if (flush == Z_FINISH) {
        FLUSH_BLOCK(s, 1);
        return finish_done;
    }
    if (s->sym_next)
        FLUSH_BLOCK(s, 0);
    return block_done;
}