=========================================================================== * Same as above, but achieves better compression. We use a lazy * evaluation for matches: a match is finally adopted only if there is * no better match at the next window position. */
(s, flush)
| 2076 | * no better match at the next window position. |
| 2077 | */ |
| 2078 | local block_state deflate_slow(s, flush) |
| 2079 | deflate_state* s; |
| 2080 | |
| 2081 | int flush; |
| 2082 | { |
| 2083 | IPos hash_head; /* head of hash chain */ |
| 2084 | int bflush; /* set if current block must be flushed */ |
| 2085 | |
| 2086 | /* Process the input block. */ |
| 2087 | for (;;) |
| 2088 | { |
| 2089 | /* Make sure that we always have enough lookahead, except |
| 2090 | * at the end of the input file. We need MAX_MATCH bytes |
| 2091 | * for the next match, plus MIN_MATCH bytes to insert the |
| 2092 | * string following the next match. |
| 2093 | */ |
| 2094 | if (s->lookahead < MIN_LOOKAHEAD) |
| 2095 | { |
| 2096 | fill_window(s); |
| 2097 | if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) |
| 2098 | { |
| 2099 | return need_more; |
| 2100 | } |
| 2101 | if (s->lookahead == 0) break; /* flush the current block */ |
| 2102 | } |
| 2103 | |
| 2104 | /* Insert the string window[strstart .. strstart+2] in the |
| 2105 | * dictionary, and set hash_head to the head of the hash chain: |
| 2106 | */ |
| 2107 | hash_head = NIL; |
| 2108 | if (s->lookahead >= MIN_MATCH) |
| 2109 | { |
| 2110 | INSERT_STRING(s, s->strstart, hash_head); |
| 2111 | } |
| 2112 | |
| 2113 | /* Find the longest match, discarding those <= prev_length. |
| 2114 | */ |
| 2115 | s->prev_length = s->match_length , s->prev_match = s->match_start; |
| 2116 | s->match_length = MIN_MATCH - 1; |
| 2117 | |
| 2118 | if (hash_head != NIL && s->prev_length < s->max_lazy_match && |
| 2119 | s->strstart - hash_head <= MAX_DIST(s)) |
| 2120 | { |
| 2121 | /* To simplify the code, we prevent matches with the string |
| 2122 | * of window index 0 (in particular we have to avoid a match |
| 2123 | * of the string with itself at the start of the input file). |
| 2124 | */ |
| 2125 | s->match_length = longest_match(s, hash_head); |
| 2126 | /* longest_match() sets match_start */ |
| 2127 | |
| 2128 | if (s->match_length <= 5 && (s->strategy == Z_FILTERED |
| 2129 | #if TOO_FAR <= 32767 |
| 2130 | || (s->match_length == MIN_MATCH && |
| 2131 | s->strstart - s->match_start > TOO_FAR) |
| 2132 | #endif |
| 2133 | )) |
| 2134 | { |
| 2135 | /* If prev_match is also MIN_MATCH, match_start is garbage |
nothing calls this directly
no test coverage detected