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 lzma_vli id lzma_attribute((__unused__)), const void *options,
314 lzma_lz_options *lz_options)
315 {
316 if (options == NULL)
317 return LZMA_PROG_ERROR;
318
319 lzma_lzma2_coder *coder = lz->coder;
320 if (coder == NULL) {
321 coder = lzma_alloc(sizeof(lzma_lzma2_coder), allocator);
322 if (coder == NULL)
323 return LZMA_MEM_ERROR;
324
325 lz->coder = coder;
326 lz->code = &lzma2_encode;
327 lz->end = &lzma2_encoder_end;
328 lz->options_update = &lzma2_encoder_options_update;
329
330 coder->lzma = NULL;
331 }
332
333 coder->opt_cur = *(const lzma_options_lzma *)(options);
334
335 coder->sequence = SEQ_INIT;
336 coder->need_properties = true;
337 coder->need_state_reset = false;
338 coder->need_dictionary_reset
339 = coder->opt_cur.preset_dict == NULL
340 || coder->opt_cur.preset_dict_size == 0;
341
342 // Initialize LZMA encoder
343 return_if_error(lzma_lzma_encoder_create(&coder->lzma, allocator,
344 LZMA_FILTER_LZMA2, &coder->opt_cur, lz_options));
345
346 // Make sure that we will always have enough history available in
347 // case we need to use uncompressed chunks. They are used when the
348 // compressed size of a chunk is not smaller than the uncompressed
349 // size, so we need to have at least LZMA2_COMPRESSED_MAX bytes
350 // history available.
351 if (lz_options->before_size + lz_options->dict_size < LZMA2_CHUNK_MAX)
352 lz_options->before_size
353 = LZMA2_CHUNK_MAX - lz_options->dict_size;
354
355 return LZMA_OK;
356 }
357
358
359 extern lzma_ret
360 lzma_lzma2_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
361 const lzma_filter_info *filters)
362 {
363 return lzma_lz_encoder_init(
364 next, allocator, filters, &lzma2_encoder_init);
365 }
366
367
368 extern uint64_t
369 lzma_lzma2_encoder_memusage(const void *options)
370 {
371 const uint64_t lzma_mem = lzma_lzma_encoder_memusage(options);
372 if (lzma_mem == UINT64_MAX)
373 return UINT64_MAX;
374
375 return sizeof(lzma_lzma2_coder) + lzma_mem;
376 }
377
378
379 extern lzma_ret
380 lzma_lzma2_props_encode(const void *options, uint8_t *out)
381 {
382 if (options == NULL)
383 return LZMA_PROG_ERROR;
384
385 const lzma_options_lzma *const opt = options;
386 uint32_t d = my_max(opt->dict_size, LZMA_DICT_SIZE_MIN);
387
388 // Round up to the next 2^n - 1 or 2^n + 2^(n - 1) - 1 depending
389 // on which one is the next:
390 --d;
391 d |= d >> 2;
392 d |= d >> 3;
393 d |= d >> 4;
394 d |= d >> 8;
395 d |= d >> 16;
396
397 // Get the highest two bits using the proper encoding:
398 if (d == UINT32_MAX)
399 out[0] = 40;
400 else
401 out[0] = get_dist_slot(d + 1) - 24;
402
403 return LZMA_OK;
404 }
405
406
407 extern uint64_t
408 lzma_lzma2_block_size(const void *options)
409 {
410 const lzma_options_lzma *const opt = options;
411
412 // Use at least 1 MiB to keep compression ratio better.
413 return my_max((uint64_t)(opt->dict_size) * 3, UINT64_C(1) << 20);
414 }