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1 ///////////////////////////////////////////////////////////////////////////////
2 //
3 /// \file       lzma2_encoder.c
4 /// \brief      LZMA2 encoder
5 ///
6 //  Authors:    Igor Pavlov
7 //              Lasse Collin
8 //
9 //  This file has been put into the public domain.
10 //  You can do whatever you want with this file.
11 //
12 ///////////////////////////////////////////////////////////////////////////////
13
14 #include "lz_encoder.h"
15 #include "lzma_encoder.h"
16 #include "fastpos.h"
17 #include "lzma2_encoder.h"
18
19
20 typedef struct {
21         enum {
22                 SEQ_INIT,
23                 SEQ_LZMA_ENCODE,
24                 SEQ_LZMA_COPY,
25                 SEQ_UNCOMPRESSED_HEADER,
26                 SEQ_UNCOMPRESSED_COPY,
27         } sequence;
28
29         /// LZMA encoder
30         void *lzma;
31
32         /// LZMA options currently in use.
33         lzma_options_lzma opt_cur;
34
35         bool need_properties;
36         bool need_state_reset;
37         bool need_dictionary_reset;
38
39         /// Uncompressed size of a chunk
40         size_t uncompressed_size;
41
42         /// Compressed size of a chunk (excluding headers); this is also used
43         /// to indicate the end of buf[] in SEQ_LZMA_COPY.
44         size_t compressed_size;
45
46         /// Read position in buf[]
47         size_t buf_pos;
48
49         /// Buffer to hold the chunk header and LZMA compressed data
50         uint8_t buf[LZMA2_HEADER_MAX + LZMA2_CHUNK_MAX];
51 } lzma_lzma2_coder;
52
53
54 static void
55 lzma2_header_lzma(lzma_lzma2_coder *coder)
56 {
57         assert(coder->uncompressed_size > 0);
58         assert(coder->uncompressed_size <= LZMA2_UNCOMPRESSED_MAX);
59         assert(coder->compressed_size > 0);
60         assert(coder->compressed_size <= LZMA2_CHUNK_MAX);
61
62         size_t pos;
63
64         if (coder->need_properties) {
65                 pos = 0;
66
67                 if (coder->need_dictionary_reset)
68                         coder->buf[pos] = 0x80 + (3 << 5);
69                 else
70                         coder->buf[pos] = 0x80 + (2 << 5);
71         } else {
72                 pos = 1;
73
74                 if (coder->need_state_reset)
75                         coder->buf[pos] = 0x80 + (1 << 5);
76                 else
77                         coder->buf[pos] = 0x80;
78         }
79
80         // Set the start position for copying.
81         coder->buf_pos = pos;
82
83         // Uncompressed size
84         size_t size = coder->uncompressed_size - 1;
85         coder->buf[pos++] += size >> 16;
86         coder->buf[pos++] = (size >> 8) & 0xFF;
87         coder->buf[pos++] = size & 0xFF;
88
89         // Compressed size
90         size = coder->compressed_size - 1;
91         coder->buf[pos++] = size >> 8;
92         coder->buf[pos++] = size & 0xFF;
93
94         // Properties, if needed
95         if (coder->need_properties)
96                 lzma_lzma_lclppb_encode(&coder->opt_cur, coder->buf + pos);
97
98         coder->need_properties = false;
99         coder->need_state_reset = false;
100         coder->need_dictionary_reset = false;
101
102         // The copying code uses coder->compressed_size to indicate the end
103         // of coder->buf[], so we need add the maximum size of the header here.
104         coder->compressed_size += LZMA2_HEADER_MAX;
105
106         return;
107 }
108
109
110 static void
111 lzma2_header_uncompressed(lzma_lzma2_coder *coder)
112 {
113         assert(coder->uncompressed_size > 0);
114         assert(coder->uncompressed_size <= LZMA2_CHUNK_MAX);
115
116         // If this is the first chunk, we need to include dictionary
117         // reset indicator.
118         if (coder->need_dictionary_reset)
119                 coder->buf[0] = 1;
120         else
121                 coder->buf[0] = 2;
122
123         coder->need_dictionary_reset = false;
124
125         // "Compressed" size
126         coder->buf[1] = (coder->uncompressed_size - 1) >> 8;
127         coder->buf[2] = (coder->uncompressed_size - 1) & 0xFF;
128
129         // Set the start position for copying.
130         coder->buf_pos = 0;
131         return;
132 }
133
134
135 static lzma_ret
136 lzma2_encode(void *coder_ptr, lzma_mf *restrict mf,
137                 uint8_t *restrict out, size_t *restrict out_pos,
138                 size_t out_size)
139 {
140         lzma_lzma2_coder *restrict coder = coder_ptr;
141
142         while (*out_pos < out_size)
143         switch (coder->sequence) {
144         case SEQ_INIT:
145                 // If there's no input left and we are flushing or finishing,
146                 // don't start a new chunk.
147                 if (mf_unencoded(mf) == 0) {
148                         // Write end of payload marker if finishing.
149                         if (mf->action == LZMA_FINISH)
150                                 out[(*out_pos)++] = 0;
151
152                         return mf->action == LZMA_RUN
153                                         ? LZMA_OK : LZMA_STREAM_END;
154                 }
155
156                 if (coder->need_state_reset)
157                         return_if_error(lzma_lzma_encoder_reset(
158                                         coder->lzma, &coder->opt_cur));
159
160                 coder->uncompressed_size = 0;
161                 coder->compressed_size = 0;
162                 coder->sequence = SEQ_LZMA_ENCODE;
163
164         // Fall through
165
166         case SEQ_LZMA_ENCODE: {
167                 // Calculate how much more uncompressed data this chunk
168                 // could accept.
169                 const uint32_t left = LZMA2_UNCOMPRESSED_MAX
170                                 - coder->uncompressed_size;
171                 uint32_t limit;
172
173                 if (left < mf->match_len_max) {
174                         // Must flush immediately since the next LZMA symbol
175                         // could make the uncompressed size of the chunk too
176                         // big.
177                         limit = 0;
178                 } else {
179                         // Calculate maximum read_limit that is OK from point
180                         // of view of LZMA2 chunk size.
181                         limit = mf->read_pos - mf->read_ahead
182                                         + left - mf->match_len_max;
183                 }
184
185                 // Save the start position so that we can update
186                 // coder->uncompressed_size.
187                 const uint32_t read_start = mf->read_pos - mf->read_ahead;
188
189                 // Call the LZMA encoder until the chunk is finished.
190                 const lzma_ret ret = lzma_lzma_encode(coder->lzma, mf,
191                                 coder->buf + LZMA2_HEADER_MAX,
192                                 &coder->compressed_size,
193                                 LZMA2_CHUNK_MAX, limit);
194
195                 coder->uncompressed_size += mf->read_pos - mf->read_ahead
196                                 - read_start;
197
198                 assert(coder->compressed_size <= LZMA2_CHUNK_MAX);
199                 assert(coder->uncompressed_size <= LZMA2_UNCOMPRESSED_MAX);
200
201                 if (ret != LZMA_STREAM_END)
202                         return LZMA_OK;
203
204                 // See if the chunk compressed. If it didn't, we encode it
205                 // as uncompressed chunk. This saves a few bytes of space
206                 // and makes decoding faster.
207                 if (coder->compressed_size >= coder->uncompressed_size) {
208                         coder->uncompressed_size += mf->read_ahead;
209                         assert(coder->uncompressed_size
210                                         <= LZMA2_UNCOMPRESSED_MAX);
211                         mf->read_ahead = 0;
212                         lzma2_header_uncompressed(coder);
213                         coder->need_state_reset = true;
214                         coder->sequence = SEQ_UNCOMPRESSED_HEADER;
215                         break;
216                 }
217
218                 // The chunk did compress at least by one byte, so we store
219                 // the chunk as LZMA.
220                 lzma2_header_lzma(coder);
221
222                 coder->sequence = SEQ_LZMA_COPY;
223         }
224
225         // Fall through
226
227         case SEQ_LZMA_COPY:
228                 // Copy the compressed chunk along its headers to the
229                 // output buffer.
230                 lzma_bufcpy(coder->buf, &coder->buf_pos,
231                                 coder->compressed_size,
232                                 out, out_pos, out_size);
233                 if (coder->buf_pos != coder->compressed_size)
234                         return LZMA_OK;
235
236                 coder->sequence = SEQ_INIT;
237                 break;
238
239         case SEQ_UNCOMPRESSED_HEADER:
240                 // Copy the three-byte header to indicate uncompressed chunk.
241                 lzma_bufcpy(coder->buf, &coder->buf_pos,
242                                 LZMA2_HEADER_UNCOMPRESSED,
243                                 out, out_pos, out_size);
244                 if (coder->buf_pos != LZMA2_HEADER_UNCOMPRESSED)
245                         return LZMA_OK;
246
247                 coder->sequence = SEQ_UNCOMPRESSED_COPY;
248
249         // Fall through
250
251         case SEQ_UNCOMPRESSED_COPY:
252                 // Copy the uncompressed data as is from the dictionary
253                 // to the output buffer.
254                 mf_read(mf, out, out_pos, out_size, &coder->uncompressed_size);
255                 if (coder->uncompressed_size != 0)
256                         return LZMA_OK;
257
258                 coder->sequence = SEQ_INIT;
259                 break;
260         }
261
262         return LZMA_OK;
263 }
264
265
266 static void
267 lzma2_encoder_end(void *coder_ptr, const lzma_allocator *allocator)
268 {
269         lzma_lzma2_coder *coder = coder_ptr;
270         lzma_free(coder->lzma, allocator);
271         lzma_free(coder, allocator);
272         return;
273 }
274
275
276 static lzma_ret
277 lzma2_encoder_options_update(void *coder_ptr, const lzma_filter *filter)
278 {
279         lzma_lzma2_coder *coder = coder_ptr;
280
281         // New options can be set only when there is no incomplete chunk.
282         // This is the case at the beginning of the raw stream and right
283         // after LZMA_SYNC_FLUSH.
284         if (filter->options == NULL || coder->sequence != SEQ_INIT)
285                 return LZMA_PROG_ERROR;
286
287         // Look if there are new options. At least for now,
288         // only lc/lp/pb can be changed.
289         const lzma_options_lzma *opt = filter->options;
290         if (coder->opt_cur.lc != opt->lc || coder->opt_cur.lp != opt->lp
291                         || coder->opt_cur.pb != opt->pb) {
292                 // Validate the options.
293                 if (opt->lc > LZMA_LCLP_MAX || opt->lp > LZMA_LCLP_MAX
294                                 || opt->lc + opt->lp > LZMA_LCLP_MAX
295                                 || opt->pb > LZMA_PB_MAX)
296                         return LZMA_OPTIONS_ERROR;
297
298                 // The new options will be used when the encoder starts
299                 // a new LZMA2 chunk.
300                 coder->opt_cur.lc = opt->lc;
301                 coder->opt_cur.lp = opt->lp;
302                 coder->opt_cur.pb = opt->pb;
303                 coder->need_properties = true;
304                 coder->need_state_reset = true;
305         }
306
307         return LZMA_OK;
308 }
309
310
311 static lzma_ret
312 lzma2_encoder_init(lzma_lz_encoder *lz, const lzma_allocator *allocator,
313                 const void *options, lzma_lz_options *lz_options)
314 {
315         if (options == NULL)
316                 return LZMA_PROG_ERROR;
317
318         lzma_lzma2_coder *coder = lz->coder;
319         if (coder == NULL) {
320                 coder = lzma_alloc(sizeof(lzma_lzma2_coder), allocator);
321                 if (coder == NULL)
322                         return LZMA_MEM_ERROR;
323
324                 lz->coder = coder;
325                 lz->code = &lzma2_encode;
326                 lz->end = &lzma2_encoder_end;
327                 lz->options_update = &lzma2_encoder_options_update;
328
329                 coder->lzma = NULL;
330         }
331
332         coder->opt_cur = *(const lzma_options_lzma *)(options);
333
334         coder->sequence = SEQ_INIT;
335         coder->need_properties = true;
336         coder->need_state_reset = false;
337         coder->need_dictionary_reset
338                         = coder->opt_cur.preset_dict == NULL
339                         || coder->opt_cur.preset_dict_size == 0;
340
341         // Initialize LZMA encoder
342         return_if_error(lzma_lzma_encoder_create(&coder->lzma, allocator,
343                         &coder->opt_cur, lz_options));
344
345         // Make sure that we will always have enough history available in
346         // case we need to use uncompressed chunks. They are used when the
347         // compressed size of a chunk is not smaller than the uncompressed
348         // size, so we need to have at least LZMA2_COMPRESSED_MAX bytes
349         // history available.
350         if (lz_options->before_size + lz_options->dict_size < LZMA2_CHUNK_MAX)
351                 lz_options->before_size
352                                 = LZMA2_CHUNK_MAX - lz_options->dict_size;
353
354         return LZMA_OK;
355 }
356
357
358 extern lzma_ret
359 lzma_lzma2_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
360                 const lzma_filter_info *filters)
361 {
362         return lzma_lz_encoder_init(
363                         next, allocator, filters, &lzma2_encoder_init);
364 }
365
366
367 extern uint64_t
368 lzma_lzma2_encoder_memusage(const void *options)
369 {
370         const uint64_t lzma_mem = lzma_lzma_encoder_memusage(options);
371         if (lzma_mem == UINT64_MAX)
372                 return UINT64_MAX;
373
374         return sizeof(lzma_lzma2_coder) + lzma_mem;
375 }
376
377
378 extern lzma_ret
379 lzma_lzma2_props_encode(const void *options, uint8_t *out)
380 {
381         const lzma_options_lzma *const opt = options;
382         uint32_t d = my_max(opt->dict_size, LZMA_DICT_SIZE_MIN);
383
384         // Round up to the next 2^n - 1 or 2^n + 2^(n - 1) - 1 depending
385         // on which one is the next:
386         --d;
387         d |= d >> 2;
388         d |= d >> 3;
389         d |= d >> 4;
390         d |= d >> 8;
391         d |= d >> 16;
392
393         // Get the highest two bits using the proper encoding:
394         if (d == UINT32_MAX)
395                 out[0] = 40;
396         else
397                 out[0] = get_dist_slot(d + 1) - 24;
398
399         return LZMA_OK;
400 }
401
402
403 extern uint64_t
404 lzma_lzma2_block_size(const void *options)
405 {
406         const lzma_options_lzma *const opt = options;
407
408         // Use at least 1 MiB to keep compression ratio better.
409         return my_max((uint64_t)(opt->dict_size) * 3, UINT64_C(1) << 20);
410 }