144 lines
3 KiB
C
144 lines
3 KiB
C
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/*
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* Copyright (c) 2010 The WebM project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#if CONFIG_DEBUG
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#include <assert.h>
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#endif
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#include <stdio.h>
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#include "treecoder.h"
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static void tree2tok(
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struct vp8_token_struct *const p,
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vp8_tree t,
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int i,
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int v,
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int L
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)
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{
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v += v;
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++L;
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do
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{
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const vp8_tree_index j = t[i++];
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if (j <= 0)
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{
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p[-j].value = v;
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p[-j].Len = L;
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}
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else
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tree2tok(p, t, j, v, L);
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}
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while (++v & 1);
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}
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void vp8_tokens_from_tree(struct vp8_token_struct *p, vp8_tree t)
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{
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tree2tok(p, t, 0, 0, 0);
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}
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void vp8_tokens_from_tree_offset(struct vp8_token_struct *p, vp8_tree t,
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int offset)
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{
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tree2tok(p - offset, t, 0, 0, 0);
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}
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static void branch_counts(
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int n, /* n = size of alphabet */
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vp8_token tok [ /* n */ ],
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vp8_tree tree,
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unsigned int branch_ct [ /* n-1 */ ] [2],
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const unsigned int num_events[ /* n */ ]
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)
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{
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const int tree_len = n - 1;
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int t = 0;
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#if CONFIG_DEBUG
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assert(tree_len);
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#endif
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do
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{
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branch_ct[t][0] = branch_ct[t][1] = 0;
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}
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while (++t < tree_len);
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t = 0;
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do
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{
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int L = tok[t].Len;
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const int enc = tok[t].value;
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const unsigned int ct = num_events[t];
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vp8_tree_index i = 0;
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do
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{
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const int b = (enc >> --L) & 1;
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const int j = i >> 1;
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#if CONFIG_DEBUG
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assert(j < tree_len && 0 <= L);
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#endif
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branch_ct [j] [b] += ct;
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i = tree[ i + b];
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}
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while (i > 0);
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#if CONFIG_DEBUG
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assert(!L);
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#endif
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}
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while (++t < n);
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}
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void vp8_tree_probs_from_distribution(
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int n, /* n = size of alphabet */
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vp8_token tok [ /* n */ ],
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vp8_tree tree,
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vp8_prob probs [ /* n-1 */ ],
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unsigned int branch_ct [ /* n-1 */ ] [2],
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const unsigned int num_events[ /* n */ ],
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unsigned int Pfac,
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int rd
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)
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{
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const int tree_len = n - 1;
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int t = 0;
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branch_counts(n, tok, tree, branch_ct, num_events);
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do
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{
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const unsigned int *const c = branch_ct[t];
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const unsigned int tot = c[0] + c[1];
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#if CONFIG_DEBUG
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assert(tot < (1 << 24)); /* no overflow below */
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#endif
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if (tot)
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{
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const unsigned int p = ((c[0] * Pfac) + (rd ? tot >> 1 : 0)) / tot;
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probs[t] = p < 256 ? (p ? p : 1) : 255; /* agree w/old version for now */
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}
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else
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probs[t] = vp8_prob_half;
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}
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while (++t < tree_len);
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}
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