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