upload sdk

git-svn-id: svn://kolibrios.org@4349 a494cfbc-eb01-0410-851d-a64ba20cac60

contrib/sdk/sources/ffmpeg/libavcodec/huffman.c

@@ -0,0 +1,176 @@
+/*
+ * Copyright (c) 2006 Konstantin Shishkov
+ * Copyright (c) 2007 Loren Merritt
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * huffman tree builder and VLC generator
+ */
+
+#include "avcodec.h"
+#include "get_bits.h"
+#include "huffman.h"
+
+/* symbol for Huffman tree node */
+#define HNODE -1
+
+typedef struct {
+    uint64_t val;
+    int name;
+} HeapElem;
+
+static void heap_sift(HeapElem *h, int root, int size)
+{
+    while (root * 2 + 1 < size) {
+        int child = root * 2 + 1;
+        if (child < size - 1 && h[child].val > h[child+1].val)
+            child++;
+        if (h[root].val > h[child].val) {
+            FFSWAP(HeapElem, h[root], h[child]);
+            root = child;
+        } else
+            break;
+    }
+}
+
+void ff_huff_gen_len_table(uint8_t *dst, const uint64_t *stats)
+{
+    HeapElem h[256];
+    int up[2*256];
+    int len[2*256];
+    int offset, i, next;
+    int size = 256;
+
+    for (offset = 1; ; offset <<= 1) {
+        for (i=0; i < size; i++) {
+            h[i].name = i;
+            h[i].val = (stats[i] << 8) + offset;
+        }
+        for (i = size / 2 - 1; i >= 0; i--)
+            heap_sift(h, i, size);
+
+        for (next = size; next < size * 2 - 1; next++) {
+            // merge the two smallest entries, and put it back in the heap
+            uint64_t min1v = h[0].val;
+            up[h[0].name] = next;
+            h[0].val = INT64_MAX;
+            heap_sift(h, 0, size);
+            up[h[0].name] = next;
+            h[0].name = next;
+            h[0].val += min1v;
+            heap_sift(h, 0, size);
+        }
+
+        len[2 * size - 2] = 0;
+        for (i = 2 * size - 3; i >= size; i--)
+            len[i] = len[up[i]] + 1;
+        for (i = 0; i < size; i++) {
+            dst[i] = len[up[i]] + 1;
+            if (dst[i] >= 32) break;
+        }
+        if (i==size) break;
+    }
+}
+
+static void get_tree_codes(uint32_t *bits, int16_t *lens, uint8_t *xlat,
+                           Node *nodes, int node,
+                           uint32_t pfx, int pl, int *pos, int no_zero_count)
+{
+    int s;
+
+    s = nodes[node].sym;
+    if (s != HNODE || (no_zero_count && !nodes[node].count)) {
+        bits[*pos] = pfx;
+        lens[*pos] = pl;
+        xlat[*pos] = s;
+        (*pos)++;
+    } else {
+        pfx <<= 1;
+        pl++;
+        get_tree_codes(bits, lens, xlat, nodes, nodes[node].n0, pfx, pl,
+                       pos, no_zero_count);
+        pfx |= 1;
+        get_tree_codes(bits, lens, xlat, nodes, nodes[node].n0 + 1, pfx, pl,
+                       pos, no_zero_count);
+    }
+}
+
+static int build_huff_tree(VLC *vlc, Node *nodes, int head, int flags, int nb_bits)
+{
+    int no_zero_count = !(flags & FF_HUFFMAN_FLAG_ZERO_COUNT);
+    uint32_t bits[256];
+    int16_t lens[256];
+    uint8_t xlat[256];
+    int pos = 0;
+
+    get_tree_codes(bits, lens, xlat, nodes, head, 0, 0,
+                   &pos, no_zero_count);
+    return ff_init_vlc_sparse(vlc, nb_bits, pos, lens, 2, 2, bits, 4, 4, xlat, 1, 1, 0);
+}
+
+
+/**
+ * nodes size must be 2*nb_codes
+ * first nb_codes nodes.count must be set
+ */
+int ff_huff_build_tree(AVCodecContext *avctx, VLC *vlc, int nb_codes, int nb_bits,
+                       Node *nodes, HuffCmp cmp, int flags)
+{
+    int i, j;
+    int cur_node;
+    int64_t sum = 0;
+
+    for (i = 0; i < nb_codes; i++) {
+        nodes[i].sym = i;
+        nodes[i].n0 = -2;
+        sum += nodes[i].count;
+    }
+
+    if (sum >> 31) {
+        av_log(avctx, AV_LOG_ERROR,
+               "Too high symbol frequencies. "
+               "Tree construction is not possible\n");
+        return -1;
+    }
+    qsort(nodes, nb_codes, sizeof(Node), cmp);
+    cur_node = nb_codes;
+    nodes[nb_codes*2-1].count = 0;
+    for (i = 0; i < nb_codes * 2 - 1; i += 2) {
+        uint32_t cur_count = nodes[i].count + nodes[i+1].count;
+        // find correct place to insert new node, and
+        // make space for the new node while at it
+        for(j = cur_node; j > i + 2; j--){
+            if(cur_count > nodes[j-1].count ||
+               (cur_count == nodes[j-1].count &&
+                !(flags & FF_HUFFMAN_FLAG_HNODE_FIRST)))
+                break;
+            nodes[j] = nodes[j - 1];
+        }
+        nodes[j].sym = HNODE;
+        nodes[j].count = cur_count;
+        nodes[j].n0 = i;
+        cur_node++;
+    }
+    if (build_huff_tree(vlc, nodes, nb_codes * 2 - 2, flags, nb_bits) < 0) {
+        av_log(avctx, AV_LOG_ERROR, "Error building tree\n");
+        return -1;
+    }
+    return 0;
+}