=========================================================================== * Scan a literal or distance tree to determine the frequencies of the codes * in the bit length tree. */
(s, tree, max_code)
| 705 | * in the bit length tree. |
| 706 | */ |
| 707 | local void scan_tree (s, tree, max_code) |
| 708 | deflate_state *s; |
| 709 | ct_data *tree; /* the tree to be scanned */ |
| 710 | int max_code; /* and its largest code of non zero frequency */ |
| 711 | { |
| 712 | int n; /* iterates over all tree elements */ |
| 713 | int prevlen = -1; /* last emitted length */ |
| 714 | int curlen; /* length of current code */ |
| 715 | int nextlen = tree[0].Len; /* length of next code */ |
| 716 | int count = 0; /* repeat count of the current code */ |
| 717 | int max_count = 7; /* max repeat count */ |
| 718 | int min_count = 4; /* min repeat count */ |
| 719 | |
| 720 | if (nextlen == 0) max_count = 138, min_count = 3; |
| 721 | tree[max_code+1].Len = (ush)0xffff; /* guard */ |
| 722 | |
| 723 | for (n = 0; n <= max_code; n++) { |
| 724 | curlen = nextlen; nextlen = tree[n+1].Len; |
| 725 | if (++count < max_count && curlen == nextlen) { |
| 726 | continue; |
| 727 | } else if (count < min_count) { |
| 728 | s->bl_tree[curlen].Freq += count; |
| 729 | } else if (curlen != 0) { |
| 730 | if (curlen != prevlen) s->bl_tree[curlen].Freq++; |
| 731 | s->bl_tree[REP_3_6].Freq++; |
| 732 | } else if (count <= 10) { |
| 733 | s->bl_tree[REPZ_3_10].Freq++; |
| 734 | } else { |
| 735 | s->bl_tree[REPZ_11_138].Freq++; |
| 736 | } |
| 737 | count = 0; prevlen = curlen; |
| 738 | if (nextlen == 0) { |
| 739 | max_count = 138, min_count = 3; |
| 740 | } else if (curlen == nextlen) { |
| 741 | max_count = 6, min_count = 3; |
| 742 | } else { |
| 743 | max_count = 7, min_count = 4; |
| 744 | } |
| 745 | } |
| 746 | } |
| 747 | |
| 748 | /* =========================================================================== |
| 749 | * Send a literal or distance tree in compressed form, using the codes in |