eda179764f
This commit replaces an integer divide with a table-lookup. It is to improve decoding speed, and at the same time, to reduce possible complications with a bug in AMD Family 12h processors: "665 Integer Divide Instruction May Cause Unpredictable Behavior" Change-Id: I678b707a538798a923850bac467e66e847e6def7
105 lines
3.2 KiB
C
105 lines
3.2 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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#ifndef VP9_COMMON_VP9_PROB_H_
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#define VP9_COMMON_VP9_PROB_H_
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#include "./vpx_config.h"
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#include "vpx_ports/mem.h"
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#include "vp9/common/vp9_common.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef uint8_t vp9_prob;
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#define MAX_PROB 255
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#define vp9_prob_half ((vp9_prob) 128)
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typedef int8_t vp9_tree_index;
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#define TREE_SIZE(leaf_count) (2 * (leaf_count) - 2)
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#define vp9_complement(x) (255 - x)
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#define MODE_MV_COUNT_SAT 20
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/* We build coding trees compactly in arrays.
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Each node of the tree is a pair of vp9_tree_indices.
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Array index often references a corresponding probability table.
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Index <= 0 means done encoding/decoding and value = -Index,
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Index > 0 means need another bit, specification at index.
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Nonnegative indices are always even; processing begins at node 0. */
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typedef const vp9_tree_index vp9_tree[];
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static INLINE vp9_prob clip_prob(int p) {
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return (p > 255) ? 255 : (p < 1) ? 1 : p;
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}
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static INLINE vp9_prob get_prob(int num, int den) {
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return (den == 0) ? 128u : clip_prob(((int64_t)num * 256 + (den >> 1)) / den);
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}
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static INLINE vp9_prob get_binary_prob(int n0, int n1) {
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return get_prob(n0, n0 + n1);
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}
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/* This function assumes prob1 and prob2 are already within [1,255] range. */
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static INLINE vp9_prob weighted_prob(int prob1, int prob2, int factor) {
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return ROUND_POWER_OF_TWO(prob1 * (256 - factor) + prob2 * factor, 8);
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}
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static INLINE vp9_prob merge_probs(vp9_prob pre_prob,
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const unsigned int ct[2],
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unsigned int count_sat,
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unsigned int max_update_factor) {
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const vp9_prob prob = get_binary_prob(ct[0], ct[1]);
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const unsigned int count = MIN(ct[0] + ct[1], count_sat);
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const unsigned int factor = max_update_factor * count / count_sat;
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return weighted_prob(pre_prob, prob, factor);
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}
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// MODE_MV_MAX_UPDATE_FACTOR (128) * count / MODE_MV_COUNT_SAT;
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static const int count_to_update_factor[MODE_MV_COUNT_SAT + 1] = {
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0, 6, 12, 19, 25, 32, 38, 44, 51, 57, 64,
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70, 76, 83, 89, 96, 102, 108, 115, 121, 128
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};
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static INLINE vp9_prob mode_mv_merge_probs(vp9_prob pre_prob,
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const unsigned int ct[2]) {
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const unsigned int den = ct[0] + ct[1];
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if (den == 0) {
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return pre_prob;
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} else {
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const unsigned int count = MIN(den, MODE_MV_COUNT_SAT);
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const unsigned int factor = count_to_update_factor[count];
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const vp9_prob prob =
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clip_prob(((int64_t)(ct[0]) * 256 + (den >> 1)) / den);
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return weighted_prob(pre_prob, prob, factor);
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}
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}
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void vp9_tree_merge_probs(const vp9_tree_index *tree, const vp9_prob *pre_probs,
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const unsigned int *counts, vp9_prob *probs);
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DECLARE_ALIGNED(16, extern const uint8_t, vp9_norm[256]);
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#ifdef __cplusplus
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} // extern "C"
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#endif
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#endif // VP9_COMMON_VP9_PROB_H_
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