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[minix.git] / external / public-domain / xz / dist / src / liblzma / lzma / lzma2_encoder.c
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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.
12 ///////////////////////////////////////////////////////////////////////////////
14 #include "lz_encoder.h"
15 #include "lzma_encoder.h"
16 #include "fastpos.h"
17 #include "lzma2_encoder.h"
20 struct lzma_coder_s {
21 enum {
22 SEQ_INIT,
23 SEQ_LZMA_ENCODE,
24 SEQ_LZMA_COPY,
25 SEQ_UNCOMPRESSED_HEADER,
26 SEQ_UNCOMPRESSED_COPY,
27 } sequence;
29 /// LZMA encoder
30 lzma_coder *lzma;
32 /// LZMA options currently in use.
33 lzma_options_lzma opt_cur;
35 bool need_properties;
36 bool need_state_reset;
37 bool need_dictionary_reset;
39 /// Uncompressed size of a chunk
40 size_t uncompressed_size;
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;
46 /// Read position in buf[]
47 size_t buf_pos;
49 /// Buffer to hold the chunk header and LZMA compressed data
50 uint8_t buf[LZMA2_HEADER_MAX + LZMA2_CHUNK_MAX];
54 static void
55 lzma2_header_lzma(lzma_coder *coder)
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);
62 size_t pos;
64 if (coder->need_properties) {
65 pos = 0;
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;
74 if (coder->need_state_reset)
75 coder->buf[pos] = 0x80 + (1 << 5);
76 else
77 coder->buf[pos] = 0x80;
80 // Set the start position for copying.
81 coder->buf_pos = pos;
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;
89 // Compressed size
90 size = coder->compressed_size - 1;
91 coder->buf[pos++] = size >> 8;
92 coder->buf[pos++] = size & 0xFF;
94 // Properties, if needed
95 if (coder->need_properties)
96 lzma_lzma_lclppb_encode(&coder->opt_cur, coder->buf + pos);
98 coder->need_properties = false;
99 coder->need_state_reset = false;
100 coder->need_dictionary_reset = false;
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;
106 return;
110 static void
111 lzma2_header_uncompressed(lzma_coder *coder)
113 assert(coder->uncompressed_size > 0);
114 assert(coder->uncompressed_size <= LZMA2_CHUNK_MAX);
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;
123 coder->need_dictionary_reset = false;
125 // "Compressed" size
126 coder->buf[1] = (coder->uncompressed_size - 1) >> 8;
127 coder->buf[2] = (coder->uncompressed_size - 1) & 0xFF;
129 // Set the start position for copying.
130 coder->buf_pos = 0;
131 return;
135 static lzma_ret
136 lzma2_encode(lzma_coder *restrict coder, lzma_mf *restrict mf,
137 uint8_t *restrict out, size_t *restrict out_pos,
138 size_t out_size)
140 while (*out_pos < out_size)
141 switch (coder->sequence) {
142 case SEQ_INIT:
143 // If there's no input left and we are flushing or finishing,
144 // don't start a new chunk.
145 if (mf_unencoded(mf) == 0) {
146 // Write end of payload marker if finishing.
147 if (mf->action == LZMA_FINISH)
148 out[(*out_pos)++] = 0;
150 return mf->action == LZMA_RUN
151 ? LZMA_OK : LZMA_STREAM_END;
154 if (coder->need_state_reset)
155 return_if_error(lzma_lzma_encoder_reset(
156 coder->lzma, &coder->opt_cur));
158 coder->uncompressed_size = 0;
159 coder->compressed_size = 0;
160 coder->sequence = SEQ_LZMA_ENCODE;
162 // Fall through
164 case SEQ_LZMA_ENCODE: {
165 // Calculate how much more uncompressed data this chunk
166 // could accept.
167 const uint32_t left = LZMA2_UNCOMPRESSED_MAX
168 - coder->uncompressed_size;
169 uint32_t limit;
171 if (left < mf->match_len_max) {
172 // Must flush immediately since the next LZMA symbol
173 // could make the uncompressed size of the chunk too
174 // big.
175 limit = 0;
176 } else {
177 // Calculate maximum read_limit that is OK from point
178 // of view of LZMA2 chunk size.
179 limit = mf->read_pos - mf->read_ahead
180 + left - mf->match_len_max;
183 // Save the start position so that we can update
184 // coder->uncompressed_size.
185 const uint32_t read_start = mf->read_pos - mf->read_ahead;
187 // Call the LZMA encoder until the chunk is finished.
188 const lzma_ret ret = lzma_lzma_encode(coder->lzma, mf,
189 coder->buf + LZMA2_HEADER_MAX,
190 &coder->compressed_size,
191 LZMA2_CHUNK_MAX, limit);
193 coder->uncompressed_size += mf->read_pos - mf->read_ahead
194 - read_start;
196 assert(coder->compressed_size <= LZMA2_CHUNK_MAX);
197 assert(coder->uncompressed_size <= LZMA2_UNCOMPRESSED_MAX);
199 if (ret != LZMA_STREAM_END)
200 return LZMA_OK;
202 // See if the chunk compressed. If it didn't, we encode it
203 // as uncompressed chunk. This saves a few bytes of space
204 // and makes decoding faster.
205 if (coder->compressed_size >= coder->uncompressed_size) {
206 coder->uncompressed_size += mf->read_ahead;
207 assert(coder->uncompressed_size
208 <= LZMA2_UNCOMPRESSED_MAX);
209 mf->read_ahead = 0;
210 lzma2_header_uncompressed(coder);
211 coder->need_state_reset = true;
212 coder->sequence = SEQ_UNCOMPRESSED_HEADER;
213 break;
216 // The chunk did compress at least by one byte, so we store
217 // the chunk as LZMA.
218 lzma2_header_lzma(coder);
220 coder->sequence = SEQ_LZMA_COPY;
223 // Fall through
225 case SEQ_LZMA_COPY:
226 // Copy the compressed chunk along its headers to the
227 // output buffer.
228 lzma_bufcpy(coder->buf, &coder->buf_pos,
229 coder->compressed_size,
230 out, out_pos, out_size);
231 if (coder->buf_pos != coder->compressed_size)
232 return LZMA_OK;
234 coder->sequence = SEQ_INIT;
235 break;
237 case SEQ_UNCOMPRESSED_HEADER:
238 // Copy the three-byte header to indicate uncompressed chunk.
239 lzma_bufcpy(coder->buf, &coder->buf_pos,
240 LZMA2_HEADER_UNCOMPRESSED,
241 out, out_pos, out_size);
242 if (coder->buf_pos != LZMA2_HEADER_UNCOMPRESSED)
243 return LZMA_OK;
245 coder->sequence = SEQ_UNCOMPRESSED_COPY;
247 // Fall through
249 case SEQ_UNCOMPRESSED_COPY:
250 // Copy the uncompressed data as is from the dictionary
251 // to the output buffer.
252 mf_read(mf, out, out_pos, out_size, &coder->uncompressed_size);
253 if (coder->uncompressed_size != 0)
254 return LZMA_OK;
256 coder->sequence = SEQ_INIT;
257 break;
260 return LZMA_OK;
264 static void
265 lzma2_encoder_end(lzma_coder *coder, const lzma_allocator *allocator)
267 lzma_free(coder->lzma, allocator);
268 lzma_free(coder, allocator);
269 return;
273 static lzma_ret
274 lzma2_encoder_options_update(lzma_coder *coder, const lzma_filter *filter)
276 // New options can be set only when there is no incomplete chunk.
277 // This is the case at the beginning of the raw stream and right
278 // after LZMA_SYNC_FLUSH.
279 if (filter->options == NULL || coder->sequence != SEQ_INIT)
280 return LZMA_PROG_ERROR;
282 // Look if there are new options. At least for now,
283 // only lc/lp/pb can be changed.
284 const lzma_options_lzma *opt = filter->options;
285 if (coder->opt_cur.lc != opt->lc || coder->opt_cur.lp != opt->lp
286 || coder->opt_cur.pb != opt->pb) {
287 // Validate the options.
288 if (opt->lc > LZMA_LCLP_MAX || opt->lp > LZMA_LCLP_MAX
289 || opt->lc + opt->lp > LZMA_LCLP_MAX
290 || opt->pb > LZMA_PB_MAX)
291 return LZMA_OPTIONS_ERROR;
293 // The new options will be used when the encoder starts
294 // a new LZMA2 chunk.
295 coder->opt_cur.lc = opt->lc;
296 coder->opt_cur.lp = opt->lp;
297 coder->opt_cur.pb = opt->pb;
298 coder->need_properties = true;
299 coder->need_state_reset = true;
302 return LZMA_OK;
306 static lzma_ret
307 lzma2_encoder_init(lzma_lz_encoder *lz, const lzma_allocator *allocator,
308 const void *options, lzma_lz_options *lz_options)
310 if (options == NULL)
311 return LZMA_PROG_ERROR;
313 if (lz->coder == NULL) {
314 lz->coder = lzma_alloc(sizeof(lzma_coder), allocator);
315 if (lz->coder == NULL)
316 return LZMA_MEM_ERROR;
318 lz->code = &lzma2_encode;
319 lz->end = &lzma2_encoder_end;
320 lz->options_update = &lzma2_encoder_options_update;
322 lz->coder->lzma = NULL;
325 lz->coder->opt_cur = *(const lzma_options_lzma *)(options);
327 lz->coder->sequence = SEQ_INIT;
328 lz->coder->need_properties = true;
329 lz->coder->need_state_reset = false;
330 lz->coder->need_dictionary_reset
331 = lz->coder->opt_cur.preset_dict == NULL
332 || lz->coder->opt_cur.preset_dict_size == 0;
334 // Initialize LZMA encoder
335 return_if_error(lzma_lzma_encoder_create(&lz->coder->lzma, allocator,
336 &lz->coder->opt_cur, lz_options));
338 // Make sure that we will always have enough history available in
339 // case we need to use uncompressed chunks. They are used when the
340 // compressed size of a chunk is not smaller than the uncompressed
341 // size, so we need to have at least LZMA2_COMPRESSED_MAX bytes
342 // history available.
343 if (lz_options->before_size + lz_options->dict_size < LZMA2_CHUNK_MAX)
344 lz_options->before_size
345 = LZMA2_CHUNK_MAX - lz_options->dict_size;
347 return LZMA_OK;
351 extern lzma_ret
352 lzma_lzma2_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
353 const lzma_filter_info *filters)
355 return lzma_lz_encoder_init(
356 next, allocator, filters, &lzma2_encoder_init);
360 extern uint64_t
361 lzma_lzma2_encoder_memusage(const void *options)
363 const uint64_t lzma_mem = lzma_lzma_encoder_memusage(options);
364 if (lzma_mem == UINT64_MAX)
365 return UINT64_MAX;
367 return sizeof(lzma_coder) + lzma_mem;
371 extern lzma_ret
372 lzma_lzma2_props_encode(const void *options, uint8_t *out)
374 const lzma_options_lzma *const opt = options;
375 uint32_t d = my_max(opt->dict_size, LZMA_DICT_SIZE_MIN);
377 // Round up to the next 2^n - 1 or 2^n + 2^(n - 1) - 1 depending
378 // on which one is the next:
379 --d;
380 d |= d >> 2;
381 d |= d >> 3;
382 d |= d >> 4;
383 d |= d >> 8;
384 d |= d >> 16;
386 // Get the highest two bits using the proper encoding:
387 if (d == UINT32_MAX)
388 out[0] = 40;
389 else
390 out[0] = get_dist_slot(d + 1) - 24;
392 return LZMA_OK;
396 extern uint64_t
397 lzma_lzma2_block_size(const void *options)
399 const lzma_options_lzma *const opt = options;
401 // Use at least 1 MiB to keep compression ratio better.
402 return my_max((uint64_t)(opt->dict_size) * 3, UINT64_C(1) << 20);