return costs->main[c];
}
-/* Given a (length, offset) pair that could be turned into a valid LZX match as
- * well as costs for the codewords in the main, length, and aligned Huffman
- * codes, return the approximate number of bits it will take to represent this
- * match in the compressed output. Take into account the match offset LRU
- * queue and also updates it. */
+/* Returns the cost, in bits, to output a repeat offset match of the specified
+ * length and position slot (repeat index) using the specified cost model. */
static u32
-lzx_match_cost(unsigned length, u32 offset, const struct lzx_costs *costs,
- struct lzx_lru_queue *queue)
+lzx_repmatch_cost(u32 len, unsigned position_slot, const struct lzx_costs *costs)
{
- unsigned position_slot;
unsigned len_header, main_symbol;
- unsigned num_extra_bits;
u32 cost = 0;
- position_slot = lzx_get_position_slot(offset, queue);
-
- len_header = min(length - LZX_MIN_MATCH_LEN, LZX_NUM_PRIMARY_LENS);
+ len_header = min(len - LZX_MIN_MATCH_LEN, LZX_NUM_PRIMARY_LENS);
main_symbol = ((position_slot << 3) | len_header) + LZX_NUM_CHARS;
/* Account for main symbol. */
cost += costs->main[main_symbol];
- /* Account for extra position information. */
- num_extra_bits = lzx_get_num_extra_bits(position_slot);
- if (num_extra_bits >= 3) {
- cost += num_extra_bits - 3;
- cost += costs->aligned[(offset + LZX_OFFSET_OFFSET) & 7];
- } else {
- cost += num_extra_bits;
- }
-
/* Account for extra length information. */
if (len_header == LZX_NUM_PRIMARY_LENS)
- cost += costs->len[length - LZX_MIN_MATCH_LEN - LZX_NUM_PRIMARY_LENS];
+ cost += costs->len[len - LZX_MIN_MATCH_LEN - LZX_NUM_PRIMARY_LENS];
return cost;
-
}
-
/* Set the cost model @c->costs from the Huffman codeword lengths specified in
* @lens.
*
unsigned num_matches;
const struct lz_match *matches;
struct lz_match match;
- unsigned longest_len;
- unsigned longest_rep_len;
- u32 longest_rep_offset;
+ u32 longest_len;
+ u32 longest_rep_len;
+ unsigned longest_rep_slot;
unsigned cur_pos;
unsigned end_pos;
+ struct lzx_mc_pos_data *optimum = c->optimum;
if (c->optimum_cur_idx != c->optimum_end_idx) {
/* Case 2: Return the next match/literal already found. */
- match.len = c->optimum[c->optimum_cur_idx].next.link -
+ match.len = optimum[c->optimum_cur_idx].next.link -
c->optimum_cur_idx;
- match.offset = c->optimum[c->optimum_cur_idx].next.match_offset;
+ match.offset = optimum[c->optimum_cur_idx].next.match_offset;
- c->optimum_cur_idx = c->optimum[c->optimum_cur_idx].next.link;
+ c->optimum_cur_idx = optimum[c->optimum_cur_idx].next.link;
return match;
}
len++;
if (len > longest_rep_len) {
longest_rep_len = len;
- longest_rep_offset = offset;
+ longest_rep_slot = i;
}
}
}
lzx_skip_bytes(c, longest_rep_len);
return (struct lz_match) {
.len = longest_rep_len,
- .offset = longest_rep_offset,
+ .offset = c->queue.R[longest_rep_slot],
};
}
/* Calculate the cost to reach the next position by coding a literal.
*/
- c->optimum[1].queue = c->queue;
- c->optimum[1].cost = lzx_literal_cost(c->cur_window[c->match_window_pos - 1],
+ optimum[1].queue = c->queue;
+ optimum[1].cost = lzx_literal_cost(c->cur_window[c->match_window_pos - 1],
&c->costs);
- c->optimum[1].prev.link = 0;
+ optimum[1].prev.link = 0;
/* Calculate the cost to reach any position up to and including that
* reached by the longest match.
if (len_header == LZX_NUM_PRIMARY_LENS)
cost += c->costs.len[len - LZX_MIN_MATCH_LEN - LZX_NUM_PRIMARY_LENS];
- c->optimum[len].queue = queue;
- c->optimum[len].prev.link = 0;
- c->optimum[len].prev.match_offset = offset;
- c->optimum[len].cost = cost;
+ optimum[len].queue = queue;
+ optimum[len].prev.link = 0;
+ optimum[len].prev.match_offset = offset;
+ optimum[len].cost = cost;
} while (++len <= matches[i].len);
}
end_pos = longest_len;
if (longest_rep_len >= LZX_MIN_MATCH_LEN) {
- struct lzx_lru_queue queue;
u32 cost;
while (end_pos < longest_rep_len)
- c->optimum[++end_pos].cost = MC_INFINITE_COST;
+ optimum[++end_pos].cost = MC_INFINITE_COST;
- queue = c->queue;
- cost = lzx_match_cost(longest_rep_len, longest_rep_offset,
- &c->costs, &queue);
- if (cost <= c->optimum[longest_rep_len].cost) {
- c->optimum[longest_rep_len].queue = queue;
- c->optimum[longest_rep_len].prev.link = 0;
- c->optimum[longest_rep_len].prev.match_offset = longest_rep_offset;
- c->optimum[longest_rep_len].cost = cost;
+ cost = lzx_repmatch_cost(longest_rep_len, longest_rep_slot,
+ &c->costs);
+ if (cost <= optimum[longest_rep_len].cost) {
+ optimum[longest_rep_len].queue = c->queue;
+ swap(optimum[longest_rep_len].queue.R[0],
+ optimum[longest_rep_len].queue.R[longest_rep_slot]);
+ optimum[longest_rep_len].prev.link = 0;
+ optimum[longest_rep_len].prev.match_offset =
+ optimum[longest_rep_len].queue.R[0];
+ optimum[longest_rep_len].cost = cost;
}
}
* position. The algorithm may find multiple paths to reach each
* position; only the lowest-cost path is saved.
*
- * The progress of the parse is tracked in the @c->optimum array, which
+ * The progress of the parse is tracked in the @optimum array, which
* for each position contains the minimum cost to reach that position,
* the index of the start of the match/literal taken to reach that
* position through the minimum-cost path, the offset of the match taken
* match/literal list.
*
* 3. Failing either of the above in a degenerate case, the loop
- * terminates when space in the @c->optimum array is exhausted.
+ * terminates when space in the @optimum array is exhausted.
* This terminates the algorithm and forces it to start returning
* matches/literals even though they may not be globally optimal.
*
unsigned limit = min(LZX_MAX_MATCH_LEN,
c->match_window_end - c->match_window_pos);
for (int i = 0; i < LZX_NUM_RECENT_OFFSETS; i++) {
- u32 offset = c->optimum[cur_pos].queue.R[i];
+ u32 offset = optimum[cur_pos].queue.R[i];
const u8 *strptr = &c->cur_window[c->match_window_pos];
const u8 *matchptr = strptr - offset;
unsigned len = 0;
len++;
if (len > longest_rep_len) {
longest_rep_len = len;
- longest_rep_offset = offset;
+ longest_rep_slot = i;
}
}
match = lzx_match_chooser_reverse_list(c, cur_pos);
/* Append the long match to the end of the list. */
- c->optimum[cur_pos].next.match_offset = longest_rep_offset;
- c->optimum[cur_pos].next.link = cur_pos + longest_rep_len;
+ optimum[cur_pos].next.match_offset =
+ optimum[cur_pos].queue.R[longest_rep_slot];
+ optimum[cur_pos].next.link = cur_pos + longest_rep_len;
c->optimum_end_idx = cur_pos + longest_rep_len;
/* Skip over the remaining bytes of the long match. */
match = lzx_match_chooser_reverse_list(c, cur_pos);
/* Append the long match to the end of the list. */
- c->optimum[cur_pos].next.match_offset =
+ optimum[cur_pos].next.match_offset =
matches[num_matches - 1].offset;
- c->optimum[cur_pos].next.link = cur_pos + longest_len;
+ optimum[cur_pos].next.link = cur_pos + longest_len;
c->optimum_end_idx = cur_pos + longest_len;
/* Skip over the remaining bytes of the long match. */
}
while (end_pos < cur_pos + longest_len)
- c->optimum[++end_pos].cost = MC_INFINITE_COST;
+ optimum[++end_pos].cost = MC_INFINITE_COST;
/* Consider coding a literal. */
- cost = c->optimum[cur_pos].cost +
+ cost = optimum[cur_pos].cost +
lzx_literal_cost(c->cur_window[c->match_window_pos - 1],
&c->costs);
- if (cost < c->optimum[cur_pos + 1].cost) {
- c->optimum[cur_pos + 1].queue = c->optimum[cur_pos].queue;
- c->optimum[cur_pos + 1].cost = cost;
- c->optimum[cur_pos + 1].prev.link = cur_pos;
+ if (cost < optimum[cur_pos + 1].cost) {
+ optimum[cur_pos + 1].queue = optimum[cur_pos].queue;
+ optimum[cur_pos + 1].cost = cost;
+ optimum[cur_pos + 1].prev.link = cur_pos;
}
/* Consider coding a match.
unsigned num_extra_bits;
offset = matches[i].offset;
- queue = c->optimum[cur_pos].queue;
- position_cost = c->optimum[cur_pos].cost;
+ queue = optimum[cur_pos].queue;
+ position_cost = optimum[cur_pos].cost;
position_slot = lzx_get_position_slot(offset, &queue);
num_extra_bits = lzx_get_num_extra_bits(position_slot);
LZX_MIN_MATCH_LEN -
LZX_NUM_PRIMARY_LENS];
}
- if (cost < c->optimum[cur_pos + len].cost) {
- c->optimum[cur_pos + len].queue = queue;
- c->optimum[cur_pos + len].prev.link = cur_pos;
- c->optimum[cur_pos + len].prev.match_offset = offset;
- c->optimum[cur_pos + len].cost = cost;
+ if (cost < optimum[cur_pos + len].cost) {
+ optimum[cur_pos + len].queue = queue;
+ optimum[cur_pos + len].prev.link = cur_pos;
+ optimum[cur_pos + len].prev.match_offset = offset;
+ optimum[cur_pos + len].cost = cost;
}
} while (++len <= matches[i].len);
}
if (longest_rep_len >= LZX_MIN_MATCH_LEN) {
- struct lzx_lru_queue queue;
while (end_pos < cur_pos + longest_rep_len)
- c->optimum[++end_pos].cost = MC_INFINITE_COST;
-
- queue = c->optimum[cur_pos].queue;
-
- cost = c->optimum[cur_pos].cost +
- lzx_match_cost(longest_rep_len, longest_rep_offset,
- &c->costs, &queue);
- if (cost <= c->optimum[cur_pos + longest_rep_len].cost) {
- c->optimum[cur_pos + longest_rep_len].queue =
- queue;
- c->optimum[cur_pos + longest_rep_len].prev.link =
+ optimum[++end_pos].cost = MC_INFINITE_COST;
+
+ cost = optimum[cur_pos].cost +
+ lzx_repmatch_cost(longest_rep_len, longest_rep_slot,
+ &c->costs);
+ if (cost <= optimum[cur_pos + longest_rep_len].cost) {
+ optimum[cur_pos + longest_rep_len].queue =
+ optimum[cur_pos].queue;
+ swap(optimum[cur_pos + longest_rep_len].queue.R[0],
+ optimum[cur_pos + longest_rep_len].queue.R[longest_rep_slot]);
+ optimum[cur_pos + longest_rep_len].prev.link =
cur_pos;
- c->optimum[cur_pos + longest_rep_len].prev.match_offset =
- longest_rep_offset;
- c->optimum[cur_pos + longest_rep_len].cost =
+ optimum[cur_pos + longest_rep_len].prev.match_offset =
+ optimum[cur_pos + longest_rep_len].queue.R[0];
+ optimum[cur_pos + longest_rep_len].cost =
cost;
}
}
projects / wimlib / blobdiff