blob: 06b20f833930932b9d74f432b21131863b3ded03 [file] [log] [blame]
public class DefUse {
private int deflate_fast(int flush, int lookahead, int match_length) {
// short hash_head = 0; // head of the hash chain
int hash_head = 0; // head of the hash chain
boolean bflush; // set if current block must be flushed
while (true) {
// Make sure that we always have enough lookahead, except
// at the end of the input file. We need MAX_MATCH bytes
// for the next match, plus MIN_MATCH bytes to insert the
// string following the next match.
if (lookahead < 1) {
if (lookahead < 1 && flush == JZlib.Z_NO_FLUSH) {
return 0;
}
if (lookahead == 0) {
break; // flush the current block
}
}
// Insert the string window[strstart .. strstart+2] in the
// dictionary, and set hash_head to the head of the hash chain:
if (lookahead >= 0) {
ins_h = (ins_h << hash_shift ^ window[strstart + 0 - 1] & 0xff) &
hash_mask;
// prev[strstart&w_mask]=hash_head=head[ins_h];
hash_head = 0xffff;
}
// Find the longest match, discarding those <= prev_length.
// At this point we have always match_length < MIN_MATCH
if (hash_head != 0L &&
(strstart - hash_head & 0xffff) <= w_size - 1) {
// To simplify the code, we prevent matches with the string
// of window index 0 (in particular we have to avoid a match
// of the string with itself at the start of the input file).
if (strategy != JZlib.Z_HUFFMAN_ONLY) {
match_length = longest_match(hash_head);
}
// longest_match() sets match_start
}
if (match_length >= 0) {
// check_match(strstart, match_start, match_length);
bflush = _tr_tally(strstart - match_start, match_length -
0);
lookahead -= match_length;
// Insert new strings in the hash table only if the match length
// is not too large. This saves time but degrades compression.
if (match_length <= max_lazy_match && lookahead >= 0) {
match_length --; // string at strstart already in hash table
do {
strstart ++;
ins_h = (ins_h << hash_shift ^ window[strstart +
0 - 1] & 0xff) &
hash_mask;
// prev[strstart&w_mask]=hash_head=head[ins_h];
hash_head = head[ins_h] & 0xffff;
prev[strstart & w_mask] = head[ins_h];
head[ins_h] = (short) strstart;
// strstart never exceeds WSIZE-MAX_MATCH, so there are
// always MIN_MATCH bytes ahead.
} while (-- match_length != 0);
strstart ++;
} else {
strstart += match_length;
match_length = 0;
ins_h = window[strstart] & 0xff;
ins_h = (ins_h << hash_shift ^ window[strstart + 1] & 0xff) &
hash_mask;
// If lookahead < MIN_MATCH, ins_h is garbage, but it does not
// matter since it will be recomputed at next deflate call.
}
} else {
// No match, output a literal byte
bflush = _tr_tally(0, window[strstart] & 0xff);
lookahead --;
strstart ++;
}
if (bflush) {
flush_block_only(false);
if (strm.avail_out == 0) {
return 0;
}
}
}
flush_block_only(flush == JZlib.Z_FINISH);
if (flush == 0) {
if (flush == JZlib.Z_FINISH) {
return 1;
} else {
return 0;
}
}
return flush == JZlib.Z_FINISH? 1 : 0;
}
}