]>
Commit | Line | Data |
---|---|---|
1 | /* | |
2 | * JFFS2 -- Journalling Flash File System, Version 2. | |
3 | * | |
4 | * Copyright © 2001-2007 Red Hat, Inc. | |
5 | * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org> | |
6 | * | |
7 | * Created by Arjan van de Ven <arjanv@redhat.com> | |
8 | * | |
9 | * For licensing information, see the file 'LICENCE' in this directory. | |
10 | * | |
11 | */ | |
12 | ||
13 | #include <linux/string.h> | |
14 | #include <linux/types.h> | |
15 | #include <linux/jffs2.h> | |
16 | #include <linux/errno.h> | |
17 | #include "compr.h" | |
18 | ||
19 | ||
20 | #define RUBIN_REG_SIZE 16 | |
21 | #define UPPER_BIT_RUBIN (((long) 1)<<(RUBIN_REG_SIZE-1)) | |
22 | #define LOWER_BITS_RUBIN ((((long) 1)<<(RUBIN_REG_SIZE-1))-1) | |
23 | ||
24 | ||
25 | #define BIT_DIVIDER_MIPS 1043 | |
26 | static int bits_mips[8] = { 277, 249, 290, 267, 229, 341, 212, 241}; | |
27 | ||
28 | struct pushpull { | |
29 | unsigned char *buf; | |
30 | unsigned int buflen; | |
31 | unsigned int ofs; | |
32 | unsigned int reserve; | |
33 | }; | |
34 | ||
35 | struct rubin_state { | |
36 | unsigned long p; | |
37 | unsigned long q; | |
38 | unsigned long rec_q; | |
39 | long bit_number; | |
40 | struct pushpull pp; | |
41 | int bit_divider; | |
42 | int bits[8]; | |
43 | }; | |
44 | ||
45 | static inline void init_pushpull(struct pushpull *pp, char *buf, | |
46 | unsigned buflen, unsigned ofs, | |
47 | unsigned reserve) | |
48 | { | |
49 | pp->buf = buf; | |
50 | pp->buflen = buflen; | |
51 | pp->ofs = ofs; | |
52 | pp->reserve = reserve; | |
53 | } | |
54 | ||
55 | static inline int pushbit(struct pushpull *pp, int bit, int use_reserved) | |
56 | { | |
57 | if (pp->ofs >= pp->buflen - (use_reserved?0:pp->reserve)) | |
58 | return -ENOSPC; | |
59 | ||
60 | if (bit) | |
61 | pp->buf[pp->ofs >> 3] |= (1<<(7-(pp->ofs & 7))); | |
62 | else | |
63 | pp->buf[pp->ofs >> 3] &= ~(1<<(7-(pp->ofs & 7))); | |
64 | ||
65 | pp->ofs++; | |
66 | ||
67 | return 0; | |
68 | } | |
69 | ||
70 | static inline int pushedbits(struct pushpull *pp) | |
71 | { | |
72 | return pp->ofs; | |
73 | } | |
74 | ||
75 | static inline int pullbit(struct pushpull *pp) | |
76 | { | |
77 | int bit; | |
78 | ||
79 | bit = (pp->buf[pp->ofs >> 3] >> (7-(pp->ofs & 7))) & 1; | |
80 | ||
81 | pp->ofs++; | |
82 | return bit; | |
83 | } | |
84 | ||
85 | static inline int pulledbits(struct pushpull *pp) | |
86 | { | |
87 | return pp->ofs; | |
88 | } | |
89 | ||
90 | ||
91 | static void init_rubin(struct rubin_state *rs, int div, int *bits) | |
92 | { | |
93 | int c; | |
94 | ||
95 | rs->q = 0; | |
96 | rs->p = (long) (2 * UPPER_BIT_RUBIN); | |
97 | rs->bit_number = (long) 0; | |
98 | rs->bit_divider = div; | |
99 | ||
100 | for (c=0; c<8; c++) | |
101 | rs->bits[c] = bits[c]; | |
102 | } | |
103 | ||
104 | ||
105 | static int encode(struct rubin_state *rs, long A, long B, int symbol) | |
106 | { | |
107 | ||
108 | long i0, i1; | |
109 | int ret; | |
110 | ||
111 | while ((rs->q >= UPPER_BIT_RUBIN) || | |
112 | ((rs->p + rs->q) <= UPPER_BIT_RUBIN)) { | |
113 | rs->bit_number++; | |
114 | ||
115 | ret = pushbit(&rs->pp, (rs->q & UPPER_BIT_RUBIN) ? 1 : 0, 0); | |
116 | if (ret) | |
117 | return ret; | |
118 | rs->q &= LOWER_BITS_RUBIN; | |
119 | rs->q <<= 1; | |
120 | rs->p <<= 1; | |
121 | } | |
122 | i0 = A * rs->p / (A + B); | |
123 | if (i0 <= 0) | |
124 | i0 = 1; | |
125 | ||
126 | if (i0 >= rs->p) | |
127 | i0 = rs->p - 1; | |
128 | ||
129 | i1 = rs->p - i0; | |
130 | ||
131 | if (symbol == 0) | |
132 | rs->p = i0; | |
133 | else { | |
134 | rs->p = i1; | |
135 | rs->q += i0; | |
136 | } | |
137 | return 0; | |
138 | } | |
139 | ||
140 | ||
141 | static void end_rubin(struct rubin_state *rs) | |
142 | { | |
143 | ||
144 | int i; | |
145 | ||
146 | for (i = 0; i < RUBIN_REG_SIZE; i++) { | |
147 | pushbit(&rs->pp, (UPPER_BIT_RUBIN & rs->q) ? 1 : 0, 1); | |
148 | rs->q &= LOWER_BITS_RUBIN; | |
149 | rs->q <<= 1; | |
150 | } | |
151 | } | |
152 | ||
153 | ||
154 | static void init_decode(struct rubin_state *rs, int div, int *bits) | |
155 | { | |
156 | init_rubin(rs, div, bits); | |
157 | ||
158 | /* behalve lower */ | |
159 | rs->rec_q = 0; | |
160 | ||
161 | for (rs->bit_number = 0; rs->bit_number++ < RUBIN_REG_SIZE; | |
162 | rs->rec_q = rs->rec_q * 2 + (long) (pullbit(&rs->pp))) | |
163 | ; | |
164 | } | |
165 | ||
166 | static void __do_decode(struct rubin_state *rs, unsigned long p, | |
167 | unsigned long q) | |
168 | { | |
169 | register unsigned long lower_bits_rubin = LOWER_BITS_RUBIN; | |
170 | unsigned long rec_q; | |
171 | int c, bits = 0; | |
172 | ||
173 | /* | |
174 | * First, work out how many bits we need from the input stream. | |
175 | * Note that we have already done the initial check on this | |
176 | * loop prior to calling this function. | |
177 | */ | |
178 | do { | |
179 | bits++; | |
180 | q &= lower_bits_rubin; | |
181 | q <<= 1; | |
182 | p <<= 1; | |
183 | } while ((q >= UPPER_BIT_RUBIN) || ((p + q) <= UPPER_BIT_RUBIN)); | |
184 | ||
185 | rs->p = p; | |
186 | rs->q = q; | |
187 | ||
188 | rs->bit_number += bits; | |
189 | ||
190 | /* | |
191 | * Now get the bits. We really want this to be "get n bits". | |
192 | */ | |
193 | rec_q = rs->rec_q; | |
194 | do { | |
195 | c = pullbit(&rs->pp); | |
196 | rec_q &= lower_bits_rubin; | |
197 | rec_q <<= 1; | |
198 | rec_q += c; | |
199 | } while (--bits); | |
200 | rs->rec_q = rec_q; | |
201 | } | |
202 | ||
203 | static int decode(struct rubin_state *rs, long A, long B) | |
204 | { | |
205 | unsigned long p = rs->p, q = rs->q; | |
206 | long i0, threshold; | |
207 | int symbol; | |
208 | ||
209 | if (q >= UPPER_BIT_RUBIN || ((p + q) <= UPPER_BIT_RUBIN)) | |
210 | __do_decode(rs, p, q); | |
211 | ||
212 | i0 = A * rs->p / (A + B); | |
213 | if (i0 <= 0) | |
214 | i0 = 1; | |
215 | ||
216 | if (i0 >= rs->p) | |
217 | i0 = rs->p - 1; | |
218 | ||
219 | threshold = rs->q + i0; | |
220 | symbol = rs->rec_q >= threshold; | |
221 | if (rs->rec_q >= threshold) { | |
222 | rs->q += i0; | |
223 | i0 = rs->p - i0; | |
224 | } | |
225 | ||
226 | rs->p = i0; | |
227 | ||
228 | return symbol; | |
229 | } | |
230 | ||
231 | ||
232 | ||
233 | static int out_byte(struct rubin_state *rs, unsigned char byte) | |
234 | { | |
235 | int i, ret; | |
236 | struct rubin_state rs_copy; | |
237 | rs_copy = *rs; | |
238 | ||
239 | for (i=0; i<8; i++) { | |
240 | ret = encode(rs, rs->bit_divider-rs->bits[i], | |
241 | rs->bits[i], byte & 1); | |
242 | if (ret) { | |
243 | /* Failed. Restore old state */ | |
244 | *rs = rs_copy; | |
245 | return ret; | |
246 | } | |
247 | byte >>= 1 ; | |
248 | } | |
249 | return 0; | |
250 | } | |
251 | ||
252 | static int in_byte(struct rubin_state *rs) | |
253 | { | |
254 | int i, result = 0, bit_divider = rs->bit_divider; | |
255 | ||
256 | for (i = 0; i < 8; i++) | |
257 | result |= decode(rs, bit_divider - rs->bits[i], | |
258 | rs->bits[i]) << i; | |
259 | ||
260 | return result; | |
261 | } | |
262 | ||
263 | ||
264 | ||
265 | static int rubin_do_compress(int bit_divider, int *bits, unsigned char *data_in, | |
266 | unsigned char *cpage_out, uint32_t *sourcelen, | |
267 | uint32_t *dstlen) | |
268 | { | |
269 | int outpos = 0; | |
270 | int pos=0; | |
271 | struct rubin_state rs; | |
272 | ||
273 | init_pushpull(&rs.pp, cpage_out, *dstlen * 8, 0, 32); | |
274 | ||
275 | init_rubin(&rs, bit_divider, bits); | |
276 | ||
277 | while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos])) | |
278 | pos++; | |
279 | ||
280 | end_rubin(&rs); | |
281 | ||
282 | if (outpos > pos) { | |
283 | /* We failed */ | |
284 | return -1; | |
285 | } | |
286 | ||
287 | /* Tell the caller how much we managed to compress, | |
288 | * and how much space it took */ | |
289 | ||
290 | outpos = (pushedbits(&rs.pp)+7)/8; | |
291 | ||
292 | if (outpos >= pos) | |
293 | return -1; /* We didn't actually compress */ | |
294 | *sourcelen = pos; | |
295 | *dstlen = outpos; | |
296 | return 0; | |
297 | } | |
298 | #if 0 | |
299 | /* _compress returns the compressed size, -1 if bigger */ | |
300 | int jffs2_rubinmips_compress(unsigned char *data_in, unsigned char *cpage_out, | |
301 | uint32_t *sourcelen, uint32_t *dstlen) | |
302 | { | |
303 | return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in, | |
304 | cpage_out, sourcelen, dstlen); | |
305 | } | |
306 | #endif | |
307 | static int jffs2_dynrubin_compress(unsigned char *data_in, | |
308 | unsigned char *cpage_out, | |
309 | uint32_t *sourcelen, uint32_t *dstlen) | |
310 | { | |
311 | int bits[8]; | |
312 | unsigned char histo[256]; | |
313 | int i; | |
314 | int ret; | |
315 | uint32_t mysrclen, mydstlen; | |
316 | ||
317 | mysrclen = *sourcelen; | |
318 | mydstlen = *dstlen - 8; | |
319 | ||
320 | if (*dstlen <= 12) | |
321 | return -1; | |
322 | ||
323 | memset(histo, 0, 256); | |
324 | for (i=0; i<mysrclen; i++) | |
325 | histo[data_in[i]]++; | |
326 | memset(bits, 0, sizeof(int)*8); | |
327 | for (i=0; i<256; i++) { | |
328 | if (i&128) | |
329 | bits[7] += histo[i]; | |
330 | if (i&64) | |
331 | bits[6] += histo[i]; | |
332 | if (i&32) | |
333 | bits[5] += histo[i]; | |
334 | if (i&16) | |
335 | bits[4] += histo[i]; | |
336 | if (i&8) | |
337 | bits[3] += histo[i]; | |
338 | if (i&4) | |
339 | bits[2] += histo[i]; | |
340 | if (i&2) | |
341 | bits[1] += histo[i]; | |
342 | if (i&1) | |
343 | bits[0] += histo[i]; | |
344 | } | |
345 | ||
346 | for (i=0; i<8; i++) { | |
347 | bits[i] = (bits[i] * 256) / mysrclen; | |
348 | if (!bits[i]) bits[i] = 1; | |
349 | if (bits[i] > 255) bits[i] = 255; | |
350 | cpage_out[i] = bits[i]; | |
351 | } | |
352 | ||
353 | ret = rubin_do_compress(256, bits, data_in, cpage_out+8, &mysrclen, | |
354 | &mydstlen); | |
355 | if (ret) | |
356 | return ret; | |
357 | ||
358 | /* Add back the 8 bytes we took for the probabilities */ | |
359 | mydstlen += 8; | |
360 | ||
361 | if (mysrclen <= mydstlen) { | |
362 | /* We compressed */ | |
363 | return -1; | |
364 | } | |
365 | ||
366 | *sourcelen = mysrclen; | |
367 | *dstlen = mydstlen; | |
368 | return 0; | |
369 | } | |
370 | ||
371 | static void rubin_do_decompress(int bit_divider, int *bits, | |
372 | unsigned char *cdata_in, | |
373 | unsigned char *page_out, uint32_t srclen, | |
374 | uint32_t destlen) | |
375 | { | |
376 | int outpos = 0; | |
377 | struct rubin_state rs; | |
378 | ||
379 | init_pushpull(&rs.pp, cdata_in, srclen, 0, 0); | |
380 | init_decode(&rs, bit_divider, bits); | |
381 | ||
382 | while (outpos < destlen) | |
383 | page_out[outpos++] = in_byte(&rs); | |
384 | } | |
385 | ||
386 | ||
387 | static int jffs2_rubinmips_decompress(unsigned char *data_in, | |
388 | unsigned char *cpage_out, | |
389 | uint32_t sourcelen, uint32_t dstlen) | |
390 | { | |
391 | rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in, | |
392 | cpage_out, sourcelen, dstlen); | |
393 | return 0; | |
394 | } | |
395 | ||
396 | static int jffs2_dynrubin_decompress(unsigned char *data_in, | |
397 | unsigned char *cpage_out, | |
398 | uint32_t sourcelen, uint32_t dstlen) | |
399 | { | |
400 | int bits[8]; | |
401 | int c; | |
402 | ||
403 | for (c=0; c<8; c++) | |
404 | bits[c] = data_in[c]; | |
405 | ||
406 | rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8, | |
407 | dstlen); | |
408 | return 0; | |
409 | } | |
410 | ||
411 | static struct jffs2_compressor jffs2_rubinmips_comp = { | |
412 | .priority = JFFS2_RUBINMIPS_PRIORITY, | |
413 | .name = "rubinmips", | |
414 | .compr = JFFS2_COMPR_DYNRUBIN, | |
415 | .compress = NULL, /*&jffs2_rubinmips_compress,*/ | |
416 | .decompress = &jffs2_rubinmips_decompress, | |
417 | #ifdef JFFS2_RUBINMIPS_DISABLED | |
418 | .disabled = 1, | |
419 | #else | |
420 | .disabled = 0, | |
421 | #endif | |
422 | }; | |
423 | ||
424 | int jffs2_rubinmips_init(void) | |
425 | { | |
426 | return jffs2_register_compressor(&jffs2_rubinmips_comp); | |
427 | } | |
428 | ||
429 | void jffs2_rubinmips_exit(void) | |
430 | { | |
431 | jffs2_unregister_compressor(&jffs2_rubinmips_comp); | |
432 | } | |
433 | ||
434 | static struct jffs2_compressor jffs2_dynrubin_comp = { | |
435 | .priority = JFFS2_DYNRUBIN_PRIORITY, | |
436 | .name = "dynrubin", | |
437 | .compr = JFFS2_COMPR_RUBINMIPS, | |
438 | .compress = jffs2_dynrubin_compress, | |
439 | .decompress = &jffs2_dynrubin_decompress, | |
440 | #ifdef JFFS2_DYNRUBIN_DISABLED | |
441 | .disabled = 1, | |
442 | #else | |
443 | .disabled = 0, | |
444 | #endif | |
445 | }; | |
446 | ||
447 | int jffs2_dynrubin_init(void) | |
448 | { | |
449 | return jffs2_register_compressor(&jffs2_dynrubin_comp); | |
450 | } | |
451 | ||
452 | void jffs2_dynrubin_exit(void) | |
453 | { | |
454 | jffs2_unregister_compressor(&jffs2_dynrubin_comp); | |
455 | } |