1// Copyright 2011 Google Inc. All Rights Reserved.
2//
3// Use of this source code is governed by a BSD-style license
4// that can be found in the COPYING file in the root of the source
5// tree. An additional intellectual property rights grant can be found
6// in the file PATENTS. All contributing project authors may
7// be found in the AUTHORS file in the root of the source tree.
8// -----------------------------------------------------------------------------
9//
10// Paginated token buffer
11//
12// A 'token' is a bit value associated with a probability, either fixed
13// or a later-to-be-determined after statistics have been collected.
14// For dynamic probability, we just record the slot id (idx) for the probability
15// value in the final probability array (uint8_t* probas in VP8EmitTokens).
16//
17// Author: Skal (pascal.massimino@gmail.com)
18
19#include <assert.h>
20#include <stdlib.h>
21#include <string.h>
22
23#include "src/enc/cost_enc.h"
24#include "src/enc/vp8i_enc.h"
25#include "src/utils/utils.h"
26
27#if !defined(DISABLE_TOKEN_BUFFER)
28
29// we use pages to reduce the number of memcpy()
30#define MIN_PAGE_SIZE 8192 // minimum number of token per page
31#define FIXED_PROBA_BIT (1u << 14)
32
33typedef uint16_t token_t; // bit #15: bit value
34 // bit #14: flags for constant proba or idx
35 // bits #0..13: slot or constant proba
36struct VP8Tokens {
37 VP8Tokens* next_; // pointer to next page
38};
39// Token data is located in memory just after the next_ field.
40// This macro is used to return their address and hide the trick.
41#define TOKEN_DATA(p) ((const token_t*)&(p)[1])
42
43//------------------------------------------------------------------------------
44
45void VP8TBufferInit(VP8TBuffer* const b, int page_size) {
46 b->tokens_ = NULL;
47 b->pages_ = NULL;
48 b->last_page_ = &b->pages_;
49 b->left_ = 0;
50 b->page_size_ = (page_size < MIN_PAGE_SIZE) ? MIN_PAGE_SIZE : page_size;
51 b->error_ = 0;
52}
53
54void VP8TBufferClear(VP8TBuffer* const b) {
55 if (b != NULL) {
56 VP8Tokens* p = b->pages_;
57 while (p != NULL) {
58 VP8Tokens* const next = p->next_;
59 WebPSafeFree(p);
60 p = next;
61 }
62 VP8TBufferInit(b, b->page_size_);
63 }
64}
65
66static int TBufferNewPage(VP8TBuffer* const b) {
67 VP8Tokens* page = NULL;
68 if (!b->error_) {
69 const size_t size = sizeof(*page) + b->page_size_ * sizeof(token_t);
70 page = (VP8Tokens*)WebPSafeMalloc(1ULL, size);
71 }
72 if (page == NULL) {
73 b->error_ = 1;
74 return 0;
75 }
76 page->next_ = NULL;
77
78 *b->last_page_ = page;
79 b->last_page_ = &page->next_;
80 b->left_ = b->page_size_;
81 b->tokens_ = (token_t*)TOKEN_DATA(page);
82 return 1;
83}
84
85//------------------------------------------------------------------------------
86
87#define TOKEN_ID(t, b, ctx) \
88 (NUM_PROBAS * ((ctx) + NUM_CTX * ((b) + NUM_BANDS * (t))))
89
90static WEBP_INLINE uint32_t AddToken(VP8TBuffer* const b, uint32_t bit,
91 uint32_t proba_idx,
92 proba_t* const stats) {
93 assert(proba_idx < FIXED_PROBA_BIT);
94 assert(bit <= 1);
95 if (b->left_ > 0 || TBufferNewPage(b)) {
96 const int slot = --b->left_;
97 b->tokens_[slot] = (bit << 15) | proba_idx;
98 }
99 VP8RecordStats(bit, stats);
100 return bit;
101}
102
103static WEBP_INLINE void AddConstantToken(VP8TBuffer* const b,
104 uint32_t bit, uint32_t proba) {
105 assert(proba < 256);
106 assert(bit <= 1);
107 if (b->left_ > 0 || TBufferNewPage(b)) {
108 const int slot = --b->left_;
109 b->tokens_[slot] = (bit << 15) | FIXED_PROBA_BIT | proba;
110 }
111}
112
113int VP8RecordCoeffTokens(int ctx, const struct VP8Residual* const res,
114 VP8TBuffer* const tokens) {
115 const int16_t* const coeffs = res->coeffs;
116 const int coeff_type = res->coeff_type;
117 const int last = res->last;
118 int n = res->first;
119 uint32_t base_id = TOKEN_ID(coeff_type, n, ctx);
120 // should be stats[VP8EncBands[n]], but it's equivalent for n=0 or 1
121 proba_t* s = res->stats[n][ctx];
122 if (!AddToken(tokens, last >= 0, base_id + 0, s + 0)) {
123 return 0;
124 }
125
126 while (n < 16) {
127 const int c = coeffs[n++];
128 const int sign = c < 0;
129 const uint32_t v = sign ? -c : c;
130 if (!AddToken(tokens, v != 0, base_id + 1, s + 1)) {
131 base_id = TOKEN_ID(coeff_type, VP8EncBands[n], 0); // ctx=0
132 s = res->stats[VP8EncBands[n]][0];
133 continue;
134 }
135 if (!AddToken(tokens, v > 1, base_id + 2, s + 2)) {
136 base_id = TOKEN_ID(coeff_type, VP8EncBands[n], 1); // ctx=1
137 s = res->stats[VP8EncBands[n]][1];
138 } else {
139 if (!AddToken(tokens, v > 4, base_id + 3, s + 3)) {
140 if (AddToken(tokens, v != 2, base_id + 4, s + 4)) {
141 AddToken(tokens, v == 4, base_id + 5, s + 5);
142 }
143 } else if (!AddToken(tokens, v > 10, base_id + 6, s + 6)) {
144 if (!AddToken(tokens, v > 6, base_id + 7, s + 7)) {
145 AddConstantToken(tokens, v == 6, 159);
146 } else {
147 AddConstantToken(tokens, v >= 9, 165);
148 AddConstantToken(tokens, !(v & 1), 145);
149 }
150 } else {
151 int mask;
152 const uint8_t* tab;
153 uint32_t residue = v - 3;
154 if (residue < (8 << 1)) { // VP8Cat3 (3b)
155 AddToken(tokens, 0, base_id + 8, s + 8);
156 AddToken(tokens, 0, base_id + 9, s + 9);
157 residue -= (8 << 0);
158 mask = 1 << 2;
159 tab = VP8Cat3;
160 } else if (residue < (8 << 2)) { // VP8Cat4 (4b)
161 AddToken(tokens, 0, base_id + 8, s + 8);
162 AddToken(tokens, 1, base_id + 9, s + 9);
163 residue -= (8 << 1);
164 mask = 1 << 3;
165 tab = VP8Cat4;
166 } else if (residue < (8 << 3)) { // VP8Cat5 (5b)
167 AddToken(tokens, 1, base_id + 8, s + 8);
168 AddToken(tokens, 0, base_id + 10, s + 9);
169 residue -= (8 << 2);
170 mask = 1 << 4;
171 tab = VP8Cat5;
172 } else { // VP8Cat6 (11b)
173 AddToken(tokens, 1, base_id + 8, s + 8);
174 AddToken(tokens, 1, base_id + 10, s + 9);
175 residue -= (8 << 3);
176 mask = 1 << 10;
177 tab = VP8Cat6;
178 }
179 while (mask) {
180 AddConstantToken(tokens, !!(residue & mask), *tab++);
181 mask >>= 1;
182 }
183 }
184 base_id = TOKEN_ID(coeff_type, VP8EncBands[n], 2); // ctx=2
185 s = res->stats[VP8EncBands[n]][2];
186 }
187 AddConstantToken(tokens, sign, 128);
188 if (n == 16 || !AddToken(tokens, n <= last, base_id + 0, s + 0)) {
189 return 1; // EOB
190 }
191 }
192 return 1;
193}
194
195#undef TOKEN_ID
196
197//------------------------------------------------------------------------------
198// Final coding pass, with known probabilities
199
200int VP8EmitTokens(VP8TBuffer* const b, VP8BitWriter* const bw,
201 const uint8_t* const probas, int final_pass) {
202 const VP8Tokens* p = b->pages_;
203 assert(!b->error_);
204 while (p != NULL) {
205 const VP8Tokens* const next = p->next_;
206 const int N = (next == NULL) ? b->left_ : 0;
207 int n = b->page_size_;
208 const token_t* const tokens = TOKEN_DATA(p);
209 while (n-- > N) {
210 const token_t token = tokens[n];
211 const int bit = (token >> 15) & 1;
212 if (token & FIXED_PROBA_BIT) {
213 VP8PutBit(bw, bit, token & 0xffu); // constant proba
214 } else {
215 VP8PutBit(bw, bit, probas[token & 0x3fffu]);
216 }
217 }
218 if (final_pass) WebPSafeFree((void*)p);
219 p = next;
220 }
221 if (final_pass) b->pages_ = NULL;
222 return 1;
223}
224
225// Size estimation
226size_t VP8EstimateTokenSize(VP8TBuffer* const b, const uint8_t* const probas) {
227 size_t size = 0;
228 const VP8Tokens* p = b->pages_;
229 assert(!b->error_);
230 while (p != NULL) {
231 const VP8Tokens* const next = p->next_;
232 const int N = (next == NULL) ? b->left_ : 0;
233 int n = b->page_size_;
234 const token_t* const tokens = TOKEN_DATA(p);
235 while (n-- > N) {
236 const token_t token = tokens[n];
237 const int bit = token & (1 << 15);
238 if (token & FIXED_PROBA_BIT) {
239 size += VP8BitCost(bit, token & 0xffu);
240 } else {
241 size += VP8BitCost(bit, probas[token & 0x3fffu]);
242 }
243 }
244 p = next;
245 }
246 return size;
247}
248
249//------------------------------------------------------------------------------
250
251#else // DISABLE_TOKEN_BUFFER
252
253void VP8TBufferInit(VP8TBuffer* const b, int page_size) {
254 (void)b;
255 (void)page_size;
256}
257void VP8TBufferClear(VP8TBuffer* const b) {
258 (void)b;
259}
260
261#endif // !DISABLE_TOKEN_BUFFER
262
263