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286 lines
8.6 KiB
C
286 lines
8.6 KiB
C
// Copyright 2011 Google Inc. 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 COPYING 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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//
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// Paginated token buffer
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//
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// A 'token' is a bit value associated with a probability, either fixed
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// or a later-to-be-determined after statistics have been collected.
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// For dynamic probability, we just record the slot id (idx) for the probability
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// value in the final probability array (uint8_t* probas in VP8EmitTokens).
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//
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// Author: Skal (pascal.massimino@gmail.com)
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#include <assert.h>
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#include <stdlib.h>
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#include <string.h>
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#include "./cost.h"
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#include "./vp8enci.h"
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#include "../utils/utils.h"
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#if !defined(DISABLE_TOKEN_BUFFER)
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// we use pages to reduce the number of memcpy()
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#define MIN_PAGE_SIZE 8192 // minimum number of token per page
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#define FIXED_PROBA_BIT (1u << 14)
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typedef uint16_t token_t; // bit #15: bit value
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// bit #14: flags for constant proba or idx
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// bits #0..13: slot or constant proba
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struct VP8Tokens {
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VP8Tokens* next_; // pointer to next page
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};
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// Token data is located in memory just after the next_ field.
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// This macro is used to return their address and hide the trick.
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#define TOKEN_DATA(p) ((const token_t*)&(p)[1])
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//------------------------------------------------------------------------------
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void VP8TBufferInit(VP8TBuffer* const b, int page_size) {
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b->tokens_ = NULL;
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b->pages_ = NULL;
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b->last_page_ = &b->pages_;
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b->left_ = 0;
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b->page_size_ = (page_size < MIN_PAGE_SIZE) ? MIN_PAGE_SIZE : page_size;
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b->error_ = 0;
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}
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void VP8TBufferClear(VP8TBuffer* const b) {
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if (b != NULL) {
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VP8Tokens* p = b->pages_;
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while (p != NULL) {
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VP8Tokens* const next = p->next_;
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WebPSafeFree(p);
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p = next;
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}
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VP8TBufferInit(b, b->page_size_);
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}
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}
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static int TBufferNewPage(VP8TBuffer* const b) {
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VP8Tokens* page = NULL;
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if (!b->error_) {
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const size_t size = sizeof(*page) + b->page_size_ * sizeof(token_t);
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page = (VP8Tokens*)WebPSafeMalloc(1ULL, size);
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}
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if (page == NULL) {
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b->error_ = 1;
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return 0;
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}
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page->next_ = NULL;
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*b->last_page_ = page;
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b->last_page_ = &page->next_;
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b->left_ = b->page_size_;
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b->tokens_ = (token_t*)TOKEN_DATA(page);
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return 1;
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}
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//------------------------------------------------------------------------------
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#define TOKEN_ID(t, b, ctx) \
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(NUM_PROBAS * ((ctx) + NUM_CTX * ((b) + NUM_BANDS * (t))))
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static WEBP_INLINE uint32_t AddToken(VP8TBuffer* const b,
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uint32_t bit, uint32_t proba_idx) {
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assert(proba_idx < FIXED_PROBA_BIT);
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assert(bit <= 1);
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if (b->left_ > 0 || TBufferNewPage(b)) {
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const int slot = --b->left_;
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b->tokens_[slot] = (bit << 15) | proba_idx;
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}
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return bit;
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}
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static WEBP_INLINE void AddConstantToken(VP8TBuffer* const b,
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uint32_t bit, uint32_t proba) {
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assert(proba < 256);
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assert(bit <= 1);
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if (b->left_ > 0 || TBufferNewPage(b)) {
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const int slot = --b->left_;
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b->tokens_[slot] = (bit << 15) | FIXED_PROBA_BIT | proba;
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}
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}
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int VP8RecordCoeffTokens(const int ctx, const int coeff_type,
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int first, int last,
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const int16_t* const coeffs,
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VP8TBuffer* const tokens) {
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int n = first;
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uint32_t base_id = TOKEN_ID(coeff_type, n, ctx);
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if (!AddToken(tokens, last >= 0, base_id + 0)) {
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return 0;
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}
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while (n < 16) {
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const int c = coeffs[n++];
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const int sign = c < 0;
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const uint32_t v = sign ? -c : c;
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if (!AddToken(tokens, v != 0, base_id + 1)) {
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base_id = TOKEN_ID(coeff_type, VP8EncBands[n], 0); // ctx=0
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continue;
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}
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if (!AddToken(tokens, v > 1, base_id + 2)) {
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base_id = TOKEN_ID(coeff_type, VP8EncBands[n], 1); // ctx=1
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} else {
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if (!AddToken(tokens, v > 4, base_id + 3)) {
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if (AddToken(tokens, v != 2, base_id + 4))
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AddToken(tokens, v == 4, base_id + 5);
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} else if (!AddToken(tokens, v > 10, base_id + 6)) {
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if (!AddToken(tokens, v > 6, base_id + 7)) {
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AddConstantToken(tokens, v == 6, 159);
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} else {
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AddConstantToken(tokens, v >= 9, 165);
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AddConstantToken(tokens, !(v & 1), 145);
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}
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} else {
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int mask;
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const uint8_t* tab;
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uint32_t residue = v - 3;
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if (residue < (8 << 1)) { // VP8Cat3 (3b)
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AddToken(tokens, 0, base_id + 8);
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AddToken(tokens, 0, base_id + 9);
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residue -= (8 << 0);
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mask = 1 << 2;
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tab = VP8Cat3;
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} else if (residue < (8 << 2)) { // VP8Cat4 (4b)
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AddToken(tokens, 0, base_id + 8);
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AddToken(tokens, 1, base_id + 9);
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residue -= (8 << 1);
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mask = 1 << 3;
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tab = VP8Cat4;
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} else if (residue < (8 << 3)) { // VP8Cat5 (5b)
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AddToken(tokens, 1, base_id + 8);
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AddToken(tokens, 0, base_id + 10);
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residue -= (8 << 2);
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mask = 1 << 4;
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tab = VP8Cat5;
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} else { // VP8Cat6 (11b)
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AddToken(tokens, 1, base_id + 8);
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AddToken(tokens, 1, base_id + 10);
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residue -= (8 << 3);
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mask = 1 << 10;
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tab = VP8Cat6;
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}
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while (mask) {
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AddConstantToken(tokens, !!(residue & mask), *tab++);
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mask >>= 1;
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}
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}
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base_id = TOKEN_ID(coeff_type, VP8EncBands[n], 2); // ctx=2
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}
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AddConstantToken(tokens, sign, 128);
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if (n == 16 || !AddToken(tokens, n <= last, base_id + 0)) {
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return 1; // EOB
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}
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}
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return 1;
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}
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#undef TOKEN_ID
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//------------------------------------------------------------------------------
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// This function works, but isn't currently used. Saved for later.
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#if 0
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static void Record(int bit, proba_t* const stats) {
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proba_t p = *stats;
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if (p >= 0xffff0000u) { // an overflow is inbound.
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p = ((p + 1u) >> 1) & 0x7fff7fffu; // -> divide the stats by 2.
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}
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// record bit count (lower 16 bits) and increment total count (upper 16 bits).
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p += 0x00010000u + bit;
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*stats = p;
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}
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void VP8TokenToStats(const VP8TBuffer* const b, proba_t* const stats) {
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const VP8Tokens* p = b->pages_;
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while (p != NULL) {
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const int N = (p->next_ == NULL) ? b->left_ : 0;
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int n = MAX_NUM_TOKEN;
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const token_t* const tokens = TOKEN_DATA(p);
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while (n-- > N) {
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const token_t token = tokens[n];
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if (!(token & FIXED_PROBA_BIT)) {
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Record((token >> 15) & 1, stats + (token & 0x3fffu));
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}
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}
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p = p->next_;
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}
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}
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#endif // 0
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//------------------------------------------------------------------------------
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// Final coding pass, with known probabilities
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int VP8EmitTokens(VP8TBuffer* const b, VP8BitWriter* const bw,
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const uint8_t* const probas, int final_pass) {
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const VP8Tokens* p = b->pages_;
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assert(!b->error_);
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while (p != NULL) {
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const VP8Tokens* const next = p->next_;
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const int N = (next == NULL) ? b->left_ : 0;
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int n = b->page_size_;
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const token_t* const tokens = TOKEN_DATA(p);
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while (n-- > N) {
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const token_t token = tokens[n];
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const int bit = (token >> 15) & 1;
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if (token & FIXED_PROBA_BIT) {
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VP8PutBit(bw, bit, token & 0xffu); // constant proba
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} else {
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VP8PutBit(bw, bit, probas[token & 0x3fffu]);
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}
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}
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if (final_pass) WebPSafeFree((void*)p);
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p = next;
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}
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if (final_pass) b->pages_ = NULL;
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return 1;
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}
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// Size estimation
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size_t VP8EstimateTokenSize(VP8TBuffer* const b, const uint8_t* const probas) {
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size_t size = 0;
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const VP8Tokens* p = b->pages_;
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assert(!b->error_);
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while (p != NULL) {
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const VP8Tokens* const next = p->next_;
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const int N = (next == NULL) ? b->left_ : 0;
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int n = b->page_size_;
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const token_t* const tokens = TOKEN_DATA(p);
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while (n-- > N) {
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const token_t token = tokens[n];
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const int bit = token & (1 << 15);
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if (token & FIXED_PROBA_BIT) {
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size += VP8BitCost(bit, token & 0xffu);
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} else {
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size += VP8BitCost(bit, probas[token & 0x3fffu]);
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}
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}
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p = next;
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}
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return size;
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}
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//------------------------------------------------------------------------------
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#else // DISABLE_TOKEN_BUFFER
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void VP8TBufferInit(VP8TBuffer* const b) {
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(void)b;
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}
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void VP8TBufferClear(VP8TBuffer* const b) {
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(void)b;
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}
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#endif // !DISABLE_TOKEN_BUFFER
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