1 | // Copyright 2010 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 | // Boolean decoder non-inlined methods |
11 | // |
12 | // Author: Skal (pascal.massimino@gmail.com) |
13 | |
14 | #ifdef HAVE_CONFIG_H |
15 | #include "src/webp/config.h" |
16 | #endif |
17 | |
18 | #include "src/utils/bit_reader_inl_utils.h" |
19 | #include "src/utils/utils.h" |
20 | |
21 | //------------------------------------------------------------------------------ |
22 | // VP8BitReader |
23 | |
24 | void VP8BitReaderSetBuffer(VP8BitReader* const br, |
25 | const uint8_t* const start, |
26 | size_t size) { |
27 | br->buf_ = start; |
28 | br->buf_end_ = start + size; |
29 | br->buf_max_ = |
30 | (size >= sizeof(lbit_t)) ? start + size - sizeof(lbit_t) + 1 |
31 | : start; |
32 | } |
33 | |
34 | void VP8InitBitReader(VP8BitReader* const br, |
35 | const uint8_t* const start, size_t size) { |
36 | assert(br != NULL); |
37 | assert(start != NULL); |
38 | assert(size < (1u << 31)); // limit ensured by format and upstream checks |
39 | br->range_ = 255 - 1; |
40 | br->value_ = 0; |
41 | br->bits_ = -8; // to load the very first 8bits |
42 | br->eof_ = 0; |
43 | VP8BitReaderSetBuffer(br, start, size); |
44 | VP8LoadNewBytes(br); |
45 | } |
46 | |
47 | void VP8RemapBitReader(VP8BitReader* const br, ptrdiff_t offset) { |
48 | if (br->buf_ != NULL) { |
49 | br->buf_ += offset; |
50 | br->buf_end_ += offset; |
51 | br->buf_max_ += offset; |
52 | } |
53 | } |
54 | |
55 | const uint8_t kVP8Log2Range[128] = { |
56 | 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4, |
57 | 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, |
58 | 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, |
59 | 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, |
60 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, |
61 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, |
62 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, |
63 | 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, |
64 | 0 |
65 | }; |
66 | |
67 | // range = ((range - 1) << kVP8Log2Range[range]) + 1 |
68 | const uint8_t kVP8NewRange[128] = { |
69 | 127, 127, 191, 127, 159, 191, 223, 127, |
70 | 143, 159, 175, 191, 207, 223, 239, 127, |
71 | 135, 143, 151, 159, 167, 175, 183, 191, |
72 | 199, 207, 215, 223, 231, 239, 247, 127, |
73 | 131, 135, 139, 143, 147, 151, 155, 159, |
74 | 163, 167, 171, 175, 179, 183, 187, 191, |
75 | 195, 199, 203, 207, 211, 215, 219, 223, |
76 | 227, 231, 235, 239, 243, 247, 251, 127, |
77 | 129, 131, 133, 135, 137, 139, 141, 143, |
78 | 145, 147, 149, 151, 153, 155, 157, 159, |
79 | 161, 163, 165, 167, 169, 171, 173, 175, |
80 | 177, 179, 181, 183, 185, 187, 189, 191, |
81 | 193, 195, 197, 199, 201, 203, 205, 207, |
82 | 209, 211, 213, 215, 217, 219, 221, 223, |
83 | 225, 227, 229, 231, 233, 235, 237, 239, |
84 | 241, 243, 245, 247, 249, 251, 253, 127 |
85 | }; |
86 | |
87 | void VP8LoadFinalBytes(VP8BitReader* const br) { |
88 | assert(br != NULL && br->buf_ != NULL); |
89 | // Only read 8bits at a time |
90 | if (br->buf_ < br->buf_end_) { |
91 | br->bits_ += 8; |
92 | br->value_ = (bit_t)(*br->buf_++) | (br->value_ << 8); |
93 | } else if (!br->eof_) { |
94 | br->value_ <<= 8; |
95 | br->bits_ += 8; |
96 | br->eof_ = 1; |
97 | } else { |
98 | br->bits_ = 0; // This is to avoid undefined behaviour with shifts. |
99 | } |
100 | } |
101 | |
102 | //------------------------------------------------------------------------------ |
103 | // Higher-level calls |
104 | |
105 | uint32_t VP8GetValue(VP8BitReader* const br, int bits, const char label[]) { |
106 | uint32_t v = 0; |
107 | while (bits-- > 0) { |
108 | v |= VP8GetBit(br, 0x80, label) << bits; |
109 | } |
110 | return v; |
111 | } |
112 | |
113 | int32_t VP8GetSignedValue(VP8BitReader* const br, int bits, |
114 | const char label[]) { |
115 | const int value = VP8GetValue(br, bits, label); |
116 | return VP8Get(br, label) ? -value : value; |
117 | } |
118 | |
119 | //------------------------------------------------------------------------------ |
120 | // VP8LBitReader |
121 | |
122 | #define VP8L_LOG8_WBITS 4 // Number of bytes needed to store VP8L_WBITS bits. |
123 | |
124 | #if defined(__arm__) || defined(_M_ARM) || defined(__aarch64__) || \ |
125 | defined(__i386__) || defined(_M_IX86) || \ |
126 | defined(__x86_64__) || defined(_M_X64) |
127 | #define VP8L_USE_FAST_LOAD |
128 | #endif |
129 | |
130 | static const uint32_t kBitMask[VP8L_MAX_NUM_BIT_READ + 1] = { |
131 | 0, |
132 | 0x000001, 0x000003, 0x000007, 0x00000f, |
133 | 0x00001f, 0x00003f, 0x00007f, 0x0000ff, |
134 | 0x0001ff, 0x0003ff, 0x0007ff, 0x000fff, |
135 | 0x001fff, 0x003fff, 0x007fff, 0x00ffff, |
136 | 0x01ffff, 0x03ffff, 0x07ffff, 0x0fffff, |
137 | 0x1fffff, 0x3fffff, 0x7fffff, 0xffffff |
138 | }; |
139 | |
140 | void VP8LInitBitReader(VP8LBitReader* const br, const uint8_t* const start, |
141 | size_t length) { |
142 | size_t i; |
143 | vp8l_val_t value = 0; |
144 | assert(br != NULL); |
145 | assert(start != NULL); |
146 | assert(length < 0xfffffff8u); // can't happen with a RIFF chunk. |
147 | |
148 | br->len_ = length; |
149 | br->val_ = 0; |
150 | br->bit_pos_ = 0; |
151 | br->eos_ = 0; |
152 | |
153 | if (length > sizeof(br->val_)) { |
154 | length = sizeof(br->val_); |
155 | } |
156 | for (i = 0; i < length; ++i) { |
157 | value |= (vp8l_val_t)start[i] << (8 * i); |
158 | } |
159 | br->val_ = value; |
160 | br->pos_ = length; |
161 | br->buf_ = start; |
162 | } |
163 | |
164 | void VP8LBitReaderSetBuffer(VP8LBitReader* const br, |
165 | const uint8_t* const buf, size_t len) { |
166 | assert(br != NULL); |
167 | assert(buf != NULL); |
168 | assert(len < 0xfffffff8u); // can't happen with a RIFF chunk. |
169 | br->buf_ = buf; |
170 | br->len_ = len; |
171 | // pos_ > len_ should be considered a param error. |
172 | br->eos_ = (br->pos_ > br->len_) || VP8LIsEndOfStream(br); |
173 | } |
174 | |
175 | static void VP8LSetEndOfStream(VP8LBitReader* const br) { |
176 | br->eos_ = 1; |
177 | br->bit_pos_ = 0; // To avoid undefined behaviour with shifts. |
178 | } |
179 | |
180 | // If not at EOS, reload up to VP8L_LBITS byte-by-byte |
181 | static void ShiftBytes(VP8LBitReader* const br) { |
182 | while (br->bit_pos_ >= 8 && br->pos_ < br->len_) { |
183 | br->val_ >>= 8; |
184 | br->val_ |= ((vp8l_val_t)br->buf_[br->pos_]) << (VP8L_LBITS - 8); |
185 | ++br->pos_; |
186 | br->bit_pos_ -= 8; |
187 | } |
188 | if (VP8LIsEndOfStream(br)) { |
189 | VP8LSetEndOfStream(br); |
190 | } |
191 | } |
192 | |
193 | void VP8LDoFillBitWindow(VP8LBitReader* const br) { |
194 | assert(br->bit_pos_ >= VP8L_WBITS); |
195 | #if defined(VP8L_USE_FAST_LOAD) |
196 | if (br->pos_ + sizeof(br->val_) < br->len_) { |
197 | br->val_ >>= VP8L_WBITS; |
198 | br->bit_pos_ -= VP8L_WBITS; |
199 | br->val_ |= (vp8l_val_t)HToLE32(WebPMemToUint32(br->buf_ + br->pos_)) << |
200 | (VP8L_LBITS - VP8L_WBITS); |
201 | br->pos_ += VP8L_LOG8_WBITS; |
202 | return; |
203 | } |
204 | #endif |
205 | ShiftBytes(br); // Slow path. |
206 | } |
207 | |
208 | uint32_t VP8LReadBits(VP8LBitReader* const br, int n_bits) { |
209 | assert(n_bits >= 0); |
210 | // Flag an error if end_of_stream or n_bits is more than allowed limit. |
211 | if (!br->eos_ && n_bits <= VP8L_MAX_NUM_BIT_READ) { |
212 | const uint32_t val = VP8LPrefetchBits(br) & kBitMask[n_bits]; |
213 | const int new_bits = br->bit_pos_ + n_bits; |
214 | br->bit_pos_ = new_bits; |
215 | ShiftBytes(br); |
216 | return val; |
217 | } else { |
218 | VP8LSetEndOfStream(br); |
219 | return 0; |
220 | } |
221 | } |
222 | |
223 | //------------------------------------------------------------------------------ |
224 | // Bit-tracing tool |
225 | |
226 | #if (BITTRACE > 0) |
227 | |
228 | #include <stdlib.h> // for atexit() |
229 | #include <stdio.h> |
230 | #include <string.h> |
231 | |
232 | #define MAX_NUM_LABELS 32 |
233 | static struct { |
234 | const char* label; |
235 | int size; |
236 | int count; |
237 | } kLabels[MAX_NUM_LABELS]; |
238 | |
239 | static int last_label = 0; |
240 | static int last_pos = 0; |
241 | static const uint8_t* buf_start = NULL; |
242 | static int init_done = 0; |
243 | |
244 | static void PrintBitTraces(void) { |
245 | int i; |
246 | int scale = 1; |
247 | int total = 0; |
248 | const char* units = "bits" ; |
249 | #if (BITTRACE == 2) |
250 | scale = 8; |
251 | units = "bytes" ; |
252 | #endif |
253 | for (i = 0; i < last_label; ++i) total += kLabels[i].size; |
254 | if (total < 1) total = 1; // avoid rounding errors |
255 | printf("=== Bit traces ===\n" ); |
256 | for (i = 0; i < last_label; ++i) { |
257 | const int skip = 16 - (int)strlen(kLabels[i].label); |
258 | const int value = (kLabels[i].size + scale - 1) / scale; |
259 | assert(skip > 0); |
260 | printf("%s \%*s: %6d %s \t[%5.2f%%] [count: %7d]\n" , |
261 | kLabels[i].label, skip, "" , value, units, |
262 | 100.f * kLabels[i].size / total, |
263 | kLabels[i].count); |
264 | } |
265 | total = (total + scale - 1) / scale; |
266 | printf("Total: %d %s\n" , total, units); |
267 | } |
268 | |
269 | void BitTrace(const struct VP8BitReader* const br, const char label[]) { |
270 | int i, pos; |
271 | if (!init_done) { |
272 | memset(kLabels, 0, sizeof(kLabels)); |
273 | atexit(PrintBitTraces); |
274 | buf_start = br->buf_; |
275 | init_done = 1; |
276 | } |
277 | pos = (int)(br->buf_ - buf_start) * 8 - br->bits_; |
278 | // if there's a too large jump, we've changed partition -> reset counter |
279 | if (abs(pos - last_pos) > 32) { |
280 | buf_start = br->buf_; |
281 | pos = 0; |
282 | last_pos = 0; |
283 | } |
284 | if (br->range_ >= 0x7f) pos += kVP8Log2Range[br->range_ - 0x7f]; |
285 | for (i = 0; i < last_label; ++i) { |
286 | if (!strcmp(label, kLabels[i].label)) break; |
287 | } |
288 | if (i == MAX_NUM_LABELS) abort(); // overflow! |
289 | kLabels[i].label = label; |
290 | kLabels[i].size += pos - last_pos; |
291 | kLabels[i].count += 1; |
292 | if (i == last_label) ++last_label; |
293 | last_pos = pos; |
294 | } |
295 | |
296 | #endif // BITTRACE > 0 |
297 | |
298 | //------------------------------------------------------------------------------ |
299 | |