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128 lines
4.8 KiB
Java
128 lines
4.8 KiB
Java
class DefUse {
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interface JZlib {
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int Z_NO_FLUSH = 0;
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int Z_HUFFMAN_ONLY = 2;
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int Z_FINISH = 4;
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}
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static class ZStream {
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int avail_out;
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}
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int strategy, ins_h, strstart, match_start, hash_shift, hash_mask, hash_head, w_size, w_mask, max_lazy_match;
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byte[] window;
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short[] prev, head;
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ZStream strm;
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int longest_match(int cur_match) { throw new UnsupportedOperationException(); }
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boolean _tr_tally(int dist, int lc) { throw new UnsupportedOperationException(); }
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void flush_block_only(boolean eof) { throw new UnsupportedOperationException(); }
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private int deflate_fast(int flush, int lookahead, int match_length) {
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// short hash_head = 0; // head of the hash chain
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int hash_head = 0; // head of the hash chain
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boolean bflush; // set if current block must be flushed
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while (true) {
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// Make sure that we always have enough lookahead, except
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// at the end of the input file. We need MAX_MATCH bytes
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// for the next match, plus MIN_MATCH bytes to insert the
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// string following the next match.
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if (lookahead < 1) {
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if (lookahead < 1 && flush == JZlib.Z_NO_FLUSH) {
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return 0;
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}
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if (lookahead == 0) {
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break; // flush the current block
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}
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}
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// Insert the string window[strstart .. strstart+2] in the
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// dictionary, and set hash_head to the head of the hash chain:
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if (lookahead >= 0) {
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ins_h = (ins_h << hash_shift ^ window[strstart + 0 - 1] & 0xff) &
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hash_mask;
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// prev[strstart&w_mask]=hash_head=head[ins_h];
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hash_head = 0xffff;
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}
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// Find the longest match, discarding those <= prev_length.
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// At this point we have always match_length < MIN_MATCH
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if (hash_head != 0L &&
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(strstart - hash_head & 0xffff) <= w_size - 1) {
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// To simplify the code, we prevent matches with the string
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// of window index 0 (in particular we have to avoid a match
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// of the string with itself at the start of the input file).
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if (strategy != JZlib.Z_HUFFMAN_ONLY) {
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match_length = longest_match(hash_head);
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}
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// longest_match() sets match_start
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}
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if (match_length >= 0) {
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// check_match(strstart, match_start, match_length);
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bflush = _tr_tally(strstart - match_start, match_length -
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0);
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lookahead -= match_length;
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// Insert new strings in the hash table only if the match length
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// is not too large. This saves time but degrades compression.
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if (match_length <= max_lazy_match && lookahead >= 0) {
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match_length --; // string at strstart already in hash table
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do {
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strstart ++;
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ins_h = (ins_h << hash_shift ^ window[strstart +
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0 - 1] & 0xff) &
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hash_mask;
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// prev[strstart&w_mask]=hash_head=head[ins_h];
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hash_head = head[ins_h] & 0xffff;
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prev[strstart & w_mask] = head[ins_h];
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head[ins_h] = (short) strstart;
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// strstart never exceeds WSIZE-MAX_MATCH, so there are
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// always MIN_MATCH bytes ahead.
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} while (-- match_length != 0);
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strstart ++;
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} else {
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strstart += match_length;
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match_length = 0;
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ins_h = window[strstart] & 0xff;
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ins_h = (ins_h << hash_shift ^ window[strstart + 1] & 0xff) &
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hash_mask;
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// If lookahead < MIN_MATCH, ins_h is garbage, but it does not
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// matter since it will be recomputed at next deflate call.
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}
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} else {
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// No match, output a literal byte
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bflush = _tr_tally(0, window[strstart] & 0xff);
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lookahead --;
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strstart ++;
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}
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if (bflush) {
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flush_block_only(false);
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if (strm.avail_out == 0) {
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return 0;
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}
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}
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}
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flush_block_only(flush == JZlib.Z_FINISH);
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if (flush == 0) {
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if (flush == JZlib.Z_FINISH) {
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return 1;
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} else {
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return 0;
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}
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}
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return flush == JZlib.Z_FINISH? 1 : 0;
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}
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}
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