LCOV - code coverage report
Current view: top level - libavcodec - huffman.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 91 97 93.8 %
Date: 2017-12-10 21:22:29 Functions: 5 5 100.0 %

          Line data    Source code
       1             : /*
       2             :  * Copyright (c) 2006 Konstantin Shishkov
       3             :  * Copyright (c) 2007 Loren Merritt
       4             :  *
       5             :  * This file is part of FFmpeg.
       6             :  *
       7             :  * FFmpeg is free software; you can redistribute it and/or
       8             :  * modify it under the terms of the GNU Lesser General Public
       9             :  * License as published by the Free Software Foundation; either
      10             :  * version 2.1 of the License, or (at your option) any later version.
      11             :  *
      12             :  * FFmpeg is distributed in the hope that it will be useful,
      13             :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      14             :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      15             :  * Lesser General Public License for more details.
      16             :  *
      17             :  * You should have received a copy of the GNU Lesser General Public
      18             :  * License along with FFmpeg; if not, write to the Free Software
      19             :  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
      20             :  */
      21             : 
      22             : /**
      23             :  * @file
      24             :  * huffman tree builder and VLC generator
      25             :  */
      26             : 
      27             : #include <stdint.h>
      28             : 
      29             : #include "libavutil/qsort.h"
      30             : #include "libavutil/common.h"
      31             : 
      32             : #include "avcodec.h"
      33             : #include "huffman.h"
      34             : #include "vlc.h"
      35             : 
      36             : /* symbol for Huffman tree node */
      37             : #define HNODE -1
      38             : 
      39             : typedef struct HeapElem {
      40             :     uint64_t val;
      41             :     int name;
      42             : } HeapElem;
      43             : 
      44     1964346 : static void heap_sift(HeapElem *h, int root, int size)
      45             : {
      46    16024403 :     while (root * 2 + 1 < size) {
      47    13302632 :         int child = root * 2 + 1;
      48    13302632 :         if (child < size - 1 && h[child].val > h[child+1].val)
      49     6146050 :             child++;
      50    13302632 :         if (h[root].val > h[child].val) {
      51    12095711 :             FFSWAP(HeapElem, h[root], h[child]);
      52    12095711 :             root = child;
      53             :         } else
      54     1206921 :             break;
      55             :     }
      56     1964346 : }
      57             : 
      58        2446 : int ff_huff_gen_len_table(uint8_t *dst, const uint64_t *stats, int stats_size, int skip0)
      59             : {
      60        2446 :     HeapElem *h  = av_malloc_array(sizeof(*h), stats_size);
      61        2446 :     int *up      = av_malloc_array(sizeof(*up) * 2, stats_size);
      62        2446 :     uint8_t *len = av_malloc_array(sizeof(*len) * 2, stats_size);
      63        2446 :     uint16_t *map= av_malloc_array(sizeof(*map), stats_size);
      64             :     int offset, i, next;
      65        2446 :     int size = 0;
      66        2446 :     int ret = 0;
      67             : 
      68        2446 :     if (!h || !up || !len || !map) {
      69           0 :         ret = AVERROR(ENOMEM);
      70           0 :         goto end;
      71             :     }
      72             : 
      73      877454 :     for (i = 0; i<stats_size; i++) {
      74      875008 :         dst[i] = 255;
      75      875008 :         if (stats[i] || !skip0)
      76      787819 :             map[size++] = i;
      77             :     }
      78             : 
      79        2446 :     for (offset = 1; ; offset <<= 1) {
      80      790265 :         for (i=0; i < size; i++) {
      81      787819 :             h[i].name = i;
      82      787819 :             h[i].val = (stats[map[i]] << 14) + offset;
      83             :         }
      84      396046 :         for (i = size / 2 - 1; i >= 0; i--)
      85      393600 :             heap_sift(h, i, size);
      86             : 
      87      787819 :         for (next = size; next < size * 2 - 1; next++) {
      88             :             // merge the two smallest entries, and put it back in the heap
      89      785373 :             uint64_t min1v = h[0].val;
      90      785373 :             up[h[0].name] = next;
      91      785373 :             h[0].val = INT64_MAX;
      92      785373 :             heap_sift(h, 0, size);
      93      785373 :             up[h[0].name] = next;
      94      785373 :             h[0].name = next;
      95      785373 :             h[0].val += min1v;
      96      785373 :             heap_sift(h, 0, size);
      97             :         }
      98             : 
      99        2446 :         len[2 * size - 2] = 0;
     100      785373 :         for (i = 2 * size - 3; i >= size; i--)
     101      782927 :             len[i] = len[up[i]] + 1;
     102      790265 :         for (i = 0; i < size; i++) {
     103      787819 :             dst[map[i]] = len[up[i]] + 1;
     104      787819 :             if (dst[map[i]] >= 32) break;
     105             :         }
     106        2446 :         if (i==size) break;
     107             :     }
     108        2446 : end:
     109        2446 :     av_free(h);
     110        2446 :     av_free(up);
     111        2446 :     av_free(len);
     112        2446 :     av_free(map);
     113        2446 :     return ret;
     114             : }
     115             : 
     116      319323 : static void get_tree_codes(uint32_t *bits, int16_t *lens, uint8_t *xlat,
     117             :                            Node *nodes, int node,
     118             :                            uint32_t pfx, int pl, int *pos, int no_zero_count)
     119             : {
     120             :     int s;
     121             : 
     122      319323 :     s = nodes[node].sym;
     123      319323 :     if (s != HNODE || (no_zero_count && !nodes[node].count)) {
     124      162210 :         bits[*pos] = pfx;
     125      162210 :         lens[*pos] = pl;
     126      162210 :         xlat[*pos] = s;
     127      162210 :         (*pos)++;
     128             :     } else {
     129      157113 :         pfx <<= 1;
     130      157113 :         pl++;
     131      157113 :         get_tree_codes(bits, lens, xlat, nodes, nodes[node].n0, pfx, pl,
     132             :                        pos, no_zero_count);
     133      157113 :         pfx |= 1;
     134      157113 :         get_tree_codes(bits, lens, xlat, nodes, nodes[node].n0 + 1, pfx, pl,
     135             :                        pos, no_zero_count);
     136             :     }
     137      319323 : }
     138             : 
     139        5097 : static int build_huff_tree(VLC *vlc, Node *nodes, int head, int flags, int nb_bits)
     140             : {
     141        5097 :     int no_zero_count = !(flags & FF_HUFFMAN_FLAG_ZERO_COUNT);
     142             :     uint32_t bits[256];
     143             :     int16_t lens[256];
     144             :     uint8_t xlat[256];
     145        5097 :     int pos = 0;
     146             : 
     147        5097 :     get_tree_codes(bits, lens, xlat, nodes, head, 0, 0,
     148             :                    &pos, no_zero_count);
     149        5097 :     return ff_init_vlc_sparse(vlc, nb_bits, pos, lens, 2, 2, bits, 4, 4, xlat, 1, 1, 0);
     150             : }
     151             : 
     152             : 
     153             : /**
     154             :  * nodes size must be 2*nb_codes
     155             :  * first nb_codes nodes.count must be set
     156             :  */
     157        5097 : int ff_huff_build_tree(AVCodecContext *avctx, VLC *vlc, int nb_codes, int nb_bits,
     158             :                        Node *nodes, HuffCmp cmp, int flags)
     159             : {
     160             :     int i, j;
     161             :     int cur_node;
     162        5097 :     int64_t sum = 0;
     163             : 
     164      167307 :     for (i = 0; i < nb_codes; i++) {
     165      162210 :         nodes[i].sym = i;
     166      162210 :         nodes[i].n0 = -2;
     167      162210 :         sum += nodes[i].count;
     168             :     }
     169             : 
     170        5097 :     if (sum >> 31) {
     171           0 :         av_log(avctx, AV_LOG_ERROR,
     172             :                "Too high symbol frequencies. "
     173             :                "Tree construction is not possible\n");
     174           0 :         return -1;
     175             :     }
     176        5097 :     AV_QSORT(nodes, nb_codes, Node, cmp);
     177        5097 :     cur_node = nb_codes;
     178        5097 :     nodes[nb_codes*2-1].count = 0;
     179      167307 :     for (i = 0; i < nb_codes * 2 - 1; i += 2) {
     180      162210 :         uint32_t cur_count = nodes[i].count + nodes[i+1].count;
     181             :         // find correct place to insert new node, and
     182             :         // make space for the new node while at it
     183     5708460 :         for(j = cur_node; j > i + 2; j--){
     184    11302947 :             if(cur_count > nodes[j-1].count ||
     185     5719100 :                (cur_count == nodes[j-1].count &&
     186      101452 :                 !(flags & FF_HUFFMAN_FLAG_HNODE_FIRST)))
     187             :                 break;
     188     5546250 :             nodes[j] = nodes[j - 1];
     189             :         }
     190      162210 :         nodes[j].sym = HNODE;
     191      162210 :         nodes[j].count = cur_count;
     192      162210 :         nodes[j].n0 = i;
     193      162210 :         cur_node++;
     194             :     }
     195        5097 :     if (build_huff_tree(vlc, nodes, nb_codes * 2 - 2, flags, nb_bits) < 0) {
     196           0 :         av_log(avctx, AV_LOG_ERROR, "Error building tree\n");
     197           0 :         return -1;
     198             :     }
     199        5097 :     return 0;
     200             : }

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