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256 lines
7.5 KiB
256 lines
7.5 KiB
// 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 "./vp8enci.h" |
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#if defined(__cplusplus) || defined(c_plusplus) |
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extern "C" { |
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#endif |
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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 MAX_NUM_TOKEN 8192 // max number of token per page |
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#define FIXED_PROBA_BIT (1u << 14) |
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struct VP8Tokens { |
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uint16_t tokens_[MAX_NUM_TOKEN]; // bit#15: bit |
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// bit #14: constant proba or idx |
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// bits 0..13: slot or constant proba |
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VP8Tokens* next_; |
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}; |
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//------------------------------------------------------------------------------ |
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void VP8TBufferInit(VP8TBuffer* const b) { |
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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->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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const VP8Tokens* p = b->pages_; |
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while (p != NULL) { |
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const VP8Tokens* const next = p->next_; |
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free((void*)p); |
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p = next; |
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} |
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VP8TBufferInit(b); |
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} |
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} |
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static int TBufferNewPage(VP8TBuffer* const b) { |
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VP8Tokens* const page = b->error_ ? NULL : (VP8Tokens*)malloc(sizeof(*page)); |
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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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*b->last_page_ = page; |
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b->last_page_ = &page->next_; |
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b->left_ = MAX_NUM_TOKEN; |
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b->tokens_ = page->tokens_; |
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page->next_ = NULL; |
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return 1; |
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} |
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//------------------------------------------------------------------------------ |
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#define TOKEN_ID(t, b, ctx, p) \ |
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((p) + NUM_PROBAS * ((ctx) + NUM_CTX * ((b) + NUM_BANDS * (t)))) |
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static WEBP_INLINE int AddToken(VP8TBuffer* const b, |
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int bit, uint32_t proba_idx) { |
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assert(proba_idx < FIXED_PROBA_BIT); |
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assert(bit == 0 || 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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int bit, int proba) { |
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assert(proba < 256); |
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assert(bit == 0 || 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(int ctx, int coeff_type, 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, 0); |
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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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int v = sign ? -c : c; |
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if (!AddToken(tokens, v != 0, base_id + 1)) { |
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ctx = 0; |
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base_id = TOKEN_ID(coeff_type, VP8EncBands[n], 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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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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if (v < 3 + (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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v -= 3 + (8 << 0); |
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mask = 1 << 2; |
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tab = VP8Cat3; |
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} else if (v < 3 + (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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v -= 3 + (8 << 1); |
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mask = 1 << 3; |
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tab = VP8Cat4; |
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} else if (v < 3 + (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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v -= 3 + (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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v -= 3 + (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, !!(v & mask), *tab++); |
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mask >>= 1; |
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} |
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} |
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ctx = 2; |
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} |
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AddConstantToken(tokens, sign, 128); |
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base_id = TOKEN_ID(coeff_type, VP8EncBands[n], ctx, 0); |
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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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while (n-- > N) { |
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const uint16_t token = p->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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(void)final_pass; |
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if (b->error_) return 0; |
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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 = MAX_NUM_TOKEN; |
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while (n-- > N) { |
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const uint16_t token = p->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) free((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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//------------------------------------------------------------------------------ |
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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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#if defined(__cplusplus) || defined(c_plusplus) |
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} // extern "C" |
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#endif
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