238 lines
7.4 KiB
C
238 lines
7.4 KiB
C
/*
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* Copyright (c) 2013 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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#include "vp9/common/vp9_common.h"
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#include "vp9/common/vp9_entropy.h"
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#include "vp9/encoder/vp9_boolhuff.h"
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#include "vp9/encoder/vp9_treewriter.h"
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#define vp9_cost_upd ((int)(vp9_cost_one(upd) - vp9_cost_zero(upd)) >> 8)
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#define vp9_cost_upd256 ((int)(vp9_cost_one(upd) - vp9_cost_zero(upd)))
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static int update_bits[255];
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static int count_uniform(int v, int n) {
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int l = get_unsigned_bits(n);
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int m;
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if (l == 0) return 0;
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m = (1 << l) - n;
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if (v < m)
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return l - 1;
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else
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return l;
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}
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static int split_index(int i, int n, int modulus) {
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int max1 = (n - 1 - modulus / 2) / modulus + 1;
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if (i % modulus == modulus / 2)
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i = i / modulus;
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else
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i = max1 + i - (i + modulus - modulus / 2) / modulus;
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return i;
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}
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static int recenter_nonneg(int v, int m) {
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if (v > (m << 1))
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return v;
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else if (v >= m)
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return ((v - m) << 1);
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else
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return ((m - v) << 1) - 1;
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}
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static int remap_prob(int v, int m) {
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int i;
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static const int map_table[MAX_PROB - 1] = {
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// generated by:
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// map_table[j] = split_index(j, MAX_PROB - 1, MODULUS_PARAM);
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20, 21, 22, 23, 24, 25, 0, 26, 27, 28, 29, 30, 31, 32, 33,
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34, 35, 36, 37, 1, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
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48, 49, 2, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,
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3, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 4, 74,
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75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 5, 86, 87, 88,
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89, 90, 91, 92, 93, 94, 95, 96, 97, 6, 98, 99, 100, 101, 102,
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103, 104, 105, 106, 107, 108, 109, 7, 110, 111, 112, 113, 114, 115, 116,
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117, 118, 119, 120, 121, 8, 122, 123, 124, 125, 126, 127, 128, 129, 130,
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131, 132, 133, 9, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144,
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145, 10, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 11,
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158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 12, 170, 171,
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172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 13, 182, 183, 184, 185,
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186, 187, 188, 189, 190, 191, 192, 193, 14, 194, 195, 196, 197, 198, 199,
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200, 201, 202, 203, 204, 205, 15, 206, 207, 208, 209, 210, 211, 212, 213,
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214, 215, 216, 217, 16, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227,
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228, 229, 17, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241,
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18, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 19,
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};
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v--;
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m--;
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if ((m << 1) <= MAX_PROB)
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i = recenter_nonneg(v, m) - 1;
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else
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i = recenter_nonneg(MAX_PROB - 1 - v, MAX_PROB - 1 - m) - 1;
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i = map_table[i];
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return i;
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}
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static int count_term_subexp(int word, int k, int num_syms) {
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int count = 0;
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int i = 0;
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int mk = 0;
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while (1) {
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int b = (i ? k + i - 1 : k);
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int a = (1 << b);
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if (num_syms <= mk + 3 * a) {
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count += count_uniform(word - mk, num_syms - mk);
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break;
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} else {
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int t = (word >= mk + a);
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count++;
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if (t) {
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i = i + 1;
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mk += a;
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} else {
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count += b;
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break;
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}
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}
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}
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return count;
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}
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static int prob_diff_update_cost(vp9_prob newp, vp9_prob oldp) {
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int delp = remap_prob(newp, oldp);
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return update_bits[delp] * 256;
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}
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static void encode_uniform(vp9_writer *w, int v, int n) {
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int l = get_unsigned_bits(n);
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int m;
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if (l == 0)
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return;
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m = (1 << l) - n;
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if (v < m) {
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vp9_write_literal(w, v, l - 1);
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} else {
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vp9_write_literal(w, m + ((v - m) >> 1), l - 1);
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vp9_write_literal(w, (v - m) & 1, 1);
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}
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}
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static void encode_term_subexp(vp9_writer *w, int word, int k, int num_syms) {
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int i = 0;
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int mk = 0;
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while (1) {
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int b = (i ? k + i - 1 : k);
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int a = (1 << b);
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if (num_syms <= mk + 3 * a) {
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encode_uniform(w, word - mk, num_syms - mk);
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break;
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} else {
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int t = (word >= mk + a);
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vp9_write_literal(w, t, 1);
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if (t) {
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i = i + 1;
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mk += a;
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} else {
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vp9_write_literal(w, word - mk, b);
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break;
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}
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}
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}
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}
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void vp9_write_prob_diff_update(vp9_writer *w, vp9_prob newp, vp9_prob oldp) {
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const int delp = remap_prob(newp, oldp);
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encode_term_subexp(w, delp, SUBEXP_PARAM, 255);
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}
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void vp9_compute_update_table() {
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int i;
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for (i = 0; i < 254; i++)
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update_bits[i] = count_term_subexp(i, SUBEXP_PARAM, 255);
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}
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int vp9_prob_diff_update_savings_search(const unsigned int *ct,
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vp9_prob oldp, vp9_prob *bestp,
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vp9_prob upd) {
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const int old_b = cost_branch256(ct, oldp);
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int bestsavings = 0;
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vp9_prob newp, bestnewp = oldp;
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const int step = *bestp > oldp ? -1 : 1;
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for (newp = *bestp; newp != oldp; newp += step) {
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const int new_b = cost_branch256(ct, newp);
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const int update_b = prob_diff_update_cost(newp, oldp) + vp9_cost_upd256;
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const int savings = old_b - new_b - update_b;
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if (savings > bestsavings) {
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bestsavings = savings;
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bestnewp = newp;
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}
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}
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*bestp = bestnewp;
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return bestsavings;
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}
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int vp9_prob_diff_update_savings_search_model(const unsigned int *ct,
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const vp9_prob *oldp,
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vp9_prob *bestp,
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vp9_prob upd,
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int b, int r) {
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int i, old_b, new_b, update_b, savings, bestsavings, step;
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int newp;
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vp9_prob bestnewp, newplist[ENTROPY_NODES], oldplist[ENTROPY_NODES];
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vp9_model_to_full_probs(oldp, oldplist);
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vpx_memcpy(newplist, oldp, sizeof(vp9_prob) * UNCONSTRAINED_NODES);
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for (i = UNCONSTRAINED_NODES, old_b = 0; i < ENTROPY_NODES; ++i)
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old_b += cost_branch256(ct + 2 * i, oldplist[i]);
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old_b += cost_branch256(ct + 2 * PIVOT_NODE, oldplist[PIVOT_NODE]);
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bestsavings = 0;
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bestnewp = oldp[PIVOT_NODE];
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step = (*bestp > oldp[PIVOT_NODE] ? -1 : 1);
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for (newp = *bestp; newp != oldp[PIVOT_NODE]; newp += step) {
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if (newp < 1 || newp > 255)
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continue;
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newplist[PIVOT_NODE] = newp;
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vp9_model_to_full_probs(newplist, newplist);
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for (i = UNCONSTRAINED_NODES, new_b = 0; i < ENTROPY_NODES; ++i)
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new_b += cost_branch256(ct + 2 * i, newplist[i]);
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new_b += cost_branch256(ct + 2 * PIVOT_NODE, newplist[PIVOT_NODE]);
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update_b = prob_diff_update_cost(newp, oldp[PIVOT_NODE]) +
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vp9_cost_upd256;
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savings = old_b - new_b - update_b;
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if (savings > bestsavings) {
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bestsavings = savings;
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bestnewp = newp;
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}
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}
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*bestp = bestnewp;
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return bestsavings;
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}
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void vp9_cond_prob_diff_update(vp9_writer *w, vp9_prob *oldp,
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const unsigned int ct[2]) {
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const vp9_prob upd = DIFF_UPDATE_PROB;
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vp9_prob newp = get_binary_prob(ct[0], ct[1]);
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const int savings = vp9_prob_diff_update_savings_search(ct, *oldp, &newp,
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upd);
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assert(newp >= 1);
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if (savings > 0) {
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vp9_write(w, 1, upd);
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vp9_write_prob_diff_update(w, newp, *oldp);
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*oldp = newp;
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} else {
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vp9_write(w, 0, upd);
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}
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}
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