Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * JFFS2 -- Journalling Flash File System, Version 2. | |
3 | * | |
c00c310e | 4 | * Copyright © 2001-2007 Red Hat, Inc. |
1da177e4 LT |
5 | * |
6 | * Created by Arjan van de Ven <arjanv@redhat.com> | |
7 | * | |
8 | * For licensing information, see the file 'LICENCE' in this directory. | |
9 | * | |
1da177e4 LT |
10 | */ |
11 | ||
1da177e4 LT |
12 | #include <linux/string.h> |
13 | #include <linux/types.h> | |
14 | #include <linux/jffs2.h> | |
c00c310e | 15 | #include <linux/errno.h> |
1da177e4 LT |
16 | #include "compr.h" |
17 | ||
c00c310e DW |
18 | |
19 | #define RUBIN_REG_SIZE 16 | |
20 | #define UPPER_BIT_RUBIN (((long) 1)<<(RUBIN_REG_SIZE-1)) | |
21 | #define LOWER_BITS_RUBIN ((((long) 1)<<(RUBIN_REG_SIZE-1))-1) | |
22 | ||
23 | ||
c00c310e DW |
24 | #define BIT_DIVIDER_MIPS 1043 |
25 | static int bits_mips[8] = { 277,249,290,267,229,341,212,241}; /* mips32 */ | |
26 | ||
27 | #include <linux/errno.h> | |
28 | ||
29 | struct pushpull { | |
30 | unsigned char *buf; | |
31 | unsigned int buflen; | |
32 | unsigned int ofs; | |
33 | unsigned int reserve; | |
34 | }; | |
35 | ||
f6449f4e AM |
36 | struct rubin_state { |
37 | unsigned long p; | |
38 | unsigned long q; | |
39 | unsigned long rec_q; | |
40 | long bit_number; | |
41 | struct pushpull pp; | |
42 | int bit_divider; | |
43 | int bits[8]; | |
44 | }; | |
c00c310e DW |
45 | |
46 | static inline void init_pushpull(struct pushpull *pp, char *buf, unsigned buflen, unsigned ofs, unsigned reserve) | |
47 | { | |
48 | pp->buf = buf; | |
49 | pp->buflen = buflen; | |
50 | pp->ofs = ofs; | |
51 | pp->reserve = reserve; | |
52 | } | |
53 | ||
54 | static inline int pushbit(struct pushpull *pp, int bit, int use_reserved) | |
55 | { | |
56 | if (pp->ofs >= pp->buflen - (use_reserved?0:pp->reserve)) { | |
57 | return -ENOSPC; | |
58 | } | |
59 | ||
60 | if (bit) { | |
61 | pp->buf[pp->ofs >> 3] |= (1<<(7-(pp->ofs &7))); | |
62 | } | |
63 | else { | |
64 | pp->buf[pp->ofs >> 3] &= ~(1<<(7-(pp->ofs &7))); | |
65 | } | |
66 | pp->ofs++; | |
67 | ||
68 | return 0; | |
69 | } | |
70 | ||
71 | static inline int pushedbits(struct pushpull *pp) | |
72 | { | |
73 | return pp->ofs; | |
74 | } | |
75 | ||
76 | static inline int pullbit(struct pushpull *pp) | |
77 | { | |
78 | int bit; | |
79 | ||
80 | bit = (pp->buf[pp->ofs >> 3] >> (7-(pp->ofs & 7))) & 1; | |
81 | ||
82 | pp->ofs++; | |
83 | return bit; | |
84 | } | |
85 | ||
86 | static inline int pulledbits(struct pushpull *pp) | |
87 | { | |
88 | return pp->ofs; | |
89 | } | |
90 | ||
91 | ||
1da177e4 | 92 | static void init_rubin(struct rubin_state *rs, int div, int *bits) |
182ec4ee | 93 | { |
1da177e4 LT |
94 | int c; |
95 | ||
96 | rs->q = 0; | |
97 | rs->p = (long) (2 * UPPER_BIT_RUBIN); | |
98 | rs->bit_number = (long) 0; | |
99 | rs->bit_divider = div; | |
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) || ((rs->p + rs->q) <= UPPER_BIT_RUBIN)) { | |
112 | rs->bit_number++; | |
182ec4ee | 113 | |
1da177e4 LT |
114 | ret = pushbit(&rs->pp, (rs->q & UPPER_BIT_RUBIN) ? 1 : 0, 0); |
115 | if (ret) | |
116 | return ret; | |
117 | rs->q &= LOWER_BITS_RUBIN; | |
118 | rs->q <<= 1; | |
119 | rs->p <<= 1; | |
120 | } | |
121 | i0 = A * rs->p / (A + B); | |
122 | if (i0 <= 0) { | |
123 | i0 = 1; | |
124 | } | |
125 | if (i0 >= rs->p) { | |
126 | i0 = rs->p - 1; | |
127 | } | |
128 | i1 = rs->p - i0; | |
129 | ||
130 | if (symbol == 0) | |
131 | rs->p = i0; | |
132 | else { | |
133 | rs->p = i1; | |
134 | rs->q += i0; | |
135 | } | |
136 | return 0; | |
137 | } | |
138 | ||
139 | ||
140 | static void end_rubin(struct rubin_state *rs) | |
182ec4ee | 141 | { |
1da177e4 LT |
142 | |
143 | int i; | |
144 | ||
145 | for (i = 0; i < RUBIN_REG_SIZE; i++) { | |
146 | pushbit(&rs->pp, (UPPER_BIT_RUBIN & rs->q) ? 1 : 0, 1); | |
147 | rs->q &= LOWER_BITS_RUBIN; | |
148 | rs->q <<= 1; | |
149 | } | |
150 | } | |
151 | ||
152 | ||
153 | static void init_decode(struct rubin_state *rs, int div, int *bits) | |
154 | { | |
182ec4ee | 155 | init_rubin(rs, div, bits); |
1da177e4 LT |
156 | |
157 | /* behalve lower */ | |
158 | rs->rec_q = 0; | |
159 | ||
160 | for (rs->bit_number = 0; rs->bit_number++ < RUBIN_REG_SIZE; rs->rec_q = rs->rec_q * 2 + (long) (pullbit(&rs->pp))) | |
161 | ; | |
162 | } | |
163 | ||
164 | static void __do_decode(struct rubin_state *rs, unsigned long p, unsigned long q) | |
165 | { | |
166 | register unsigned long lower_bits_rubin = LOWER_BITS_RUBIN; | |
167 | unsigned long rec_q; | |
168 | int c, bits = 0; | |
169 | ||
170 | /* | |
171 | * First, work out how many bits we need from the input stream. | |
172 | * Note that we have already done the initial check on this | |
173 | * loop prior to calling this function. | |
174 | */ | |
175 | do { | |
176 | bits++; | |
177 | q &= lower_bits_rubin; | |
178 | q <<= 1; | |
179 | p <<= 1; | |
180 | } while ((q >= UPPER_BIT_RUBIN) || ((p + q) <= UPPER_BIT_RUBIN)); | |
181 | ||
182 | rs->p = p; | |
183 | rs->q = q; | |
184 | ||
185 | rs->bit_number += bits; | |
186 | ||
187 | /* | |
188 | * Now get the bits. We really want this to be "get n bits". | |
189 | */ | |
190 | rec_q = rs->rec_q; | |
191 | do { | |
192 | c = pullbit(&rs->pp); | |
193 | rec_q &= lower_bits_rubin; | |
194 | rec_q <<= 1; | |
195 | rec_q += c; | |
196 | } while (--bits); | |
197 | rs->rec_q = rec_q; | |
198 | } | |
199 | ||
200 | static int decode(struct rubin_state *rs, long A, long B) | |
201 | { | |
202 | unsigned long p = rs->p, q = rs->q; | |
203 | long i0, threshold; | |
204 | int symbol; | |
205 | ||
206 | if (q >= UPPER_BIT_RUBIN || ((p + q) <= UPPER_BIT_RUBIN)) | |
207 | __do_decode(rs, p, q); | |
208 | ||
209 | i0 = A * rs->p / (A + B); | |
210 | if (i0 <= 0) { | |
211 | i0 = 1; | |
212 | } | |
213 | if (i0 >= rs->p) { | |
214 | i0 = rs->p - 1; | |
215 | } | |
216 | ||
217 | threshold = rs->q + i0; | |
218 | symbol = rs->rec_q >= threshold; | |
219 | if (rs->rec_q >= threshold) { | |
220 | rs->q += i0; | |
221 | i0 = rs->p - i0; | |
222 | } | |
223 | ||
224 | rs->p = i0; | |
225 | ||
226 | return symbol; | |
227 | } | |
228 | ||
229 | ||
230 | ||
231 | static int out_byte(struct rubin_state *rs, unsigned char byte) | |
232 | { | |
233 | int i, ret; | |
234 | struct rubin_state rs_copy; | |
235 | rs_copy = *rs; | |
236 | ||
237 | for (i=0;i<8;i++) { | |
238 | ret = encode(rs, rs->bit_divider-rs->bits[i],rs->bits[i],byte&1); | |
239 | if (ret) { | |
240 | /* Failed. Restore old state */ | |
241 | *rs = rs_copy; | |
242 | return ret; | |
243 | } | |
244 | byte=byte>>1; | |
245 | } | |
246 | return 0; | |
247 | } | |
248 | ||
249 | static int in_byte(struct rubin_state *rs) | |
250 | { | |
251 | int i, result = 0, bit_divider = rs->bit_divider; | |
252 | ||
253 | for (i = 0; i < 8; i++) | |
254 | result |= decode(rs, bit_divider - rs->bits[i], rs->bits[i]) << i; | |
255 | ||
256 | return result; | |
257 | } | |
258 | ||
259 | ||
260 | ||
182ec4ee | 261 | static int rubin_do_compress(int bit_divider, int *bits, unsigned char *data_in, |
1da177e4 LT |
262 | unsigned char *cpage_out, uint32_t *sourcelen, uint32_t *dstlen) |
263 | { | |
264 | int outpos = 0; | |
265 | int pos=0; | |
266 | struct rubin_state rs; | |
267 | ||
268 | init_pushpull(&rs.pp, cpage_out, *dstlen * 8, 0, 32); | |
269 | ||
270 | init_rubin(&rs, bit_divider, bits); | |
182ec4ee | 271 | |
1da177e4 LT |
272 | while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos])) |
273 | pos++; | |
182ec4ee | 274 | |
1da177e4 LT |
275 | end_rubin(&rs); |
276 | ||
277 | if (outpos > pos) { | |
278 | /* We failed */ | |
279 | return -1; | |
280 | } | |
182ec4ee TG |
281 | |
282 | /* Tell the caller how much we managed to compress, | |
1da177e4 | 283 | * and how much space it took */ |
182ec4ee | 284 | |
1da177e4 | 285 | outpos = (pushedbits(&rs.pp)+7)/8; |
182ec4ee | 286 | |
1da177e4 LT |
287 | if (outpos >= pos) |
288 | return -1; /* We didn't actually compress */ | |
289 | *sourcelen = pos; | |
290 | *dstlen = outpos; | |
291 | return 0; | |
182ec4ee | 292 | } |
1da177e4 LT |
293 | #if 0 |
294 | /* _compress returns the compressed size, -1 if bigger */ | |
182ec4ee | 295 | int jffs2_rubinmips_compress(unsigned char *data_in, unsigned char *cpage_out, |
1da177e4 LT |
296 | uint32_t *sourcelen, uint32_t *dstlen, void *model) |
297 | { | |
298 | return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen); | |
299 | } | |
300 | #endif | |
75c96f85 AB |
301 | static int jffs2_dynrubin_compress(unsigned char *data_in, |
302 | unsigned char *cpage_out, | |
303 | uint32_t *sourcelen, uint32_t *dstlen, | |
304 | void *model) | |
1da177e4 LT |
305 | { |
306 | int bits[8]; | |
307 | unsigned char histo[256]; | |
308 | int i; | |
309 | int ret; | |
310 | uint32_t mysrclen, mydstlen; | |
311 | ||
312 | mysrclen = *sourcelen; | |
313 | mydstlen = *dstlen - 8; | |
314 | ||
315 | if (*dstlen <= 12) | |
316 | return -1; | |
317 | ||
318 | memset(histo, 0, 256); | |
319 | for (i=0; i<mysrclen; i++) { | |
320 | histo[data_in[i]]++; | |
321 | } | |
322 | memset(bits, 0, sizeof(int)*8); | |
323 | for (i=0; i<256; i++) { | |
324 | if (i&128) | |
325 | bits[7] += histo[i]; | |
326 | if (i&64) | |
327 | bits[6] += histo[i]; | |
328 | if (i&32) | |
329 | bits[5] += histo[i]; | |
330 | if (i&16) | |
331 | bits[4] += histo[i]; | |
332 | if (i&8) | |
333 | bits[3] += histo[i]; | |
334 | if (i&4) | |
335 | bits[2] += histo[i]; | |
336 | if (i&2) | |
337 | bits[1] += histo[i]; | |
338 | if (i&1) | |
339 | bits[0] += histo[i]; | |
340 | } | |
341 | ||
342 | for (i=0; i<8; i++) { | |
343 | bits[i] = (bits[i] * 256) / mysrclen; | |
344 | if (!bits[i]) bits[i] = 1; | |
345 | if (bits[i] > 255) bits[i] = 255; | |
346 | cpage_out[i] = bits[i]; | |
347 | } | |
348 | ||
349 | ret = rubin_do_compress(256, bits, data_in, cpage_out+8, &mysrclen, &mydstlen); | |
182ec4ee | 350 | if (ret) |
1da177e4 LT |
351 | return ret; |
352 | ||
353 | /* Add back the 8 bytes we took for the probabilities */ | |
354 | mydstlen += 8; | |
355 | ||
356 | if (mysrclen <= mydstlen) { | |
357 | /* We compressed */ | |
358 | return -1; | |
359 | } | |
360 | ||
361 | *sourcelen = mysrclen; | |
362 | *dstlen = mydstlen; | |
363 | return 0; | |
364 | } | |
365 | ||
182ec4ee | 366 | static void rubin_do_decompress(int bit_divider, int *bits, unsigned char *cdata_in, |
1da177e4 LT |
367 | unsigned char *page_out, uint32_t srclen, uint32_t destlen) |
368 | { | |
369 | int outpos = 0; | |
370 | struct rubin_state rs; | |
182ec4ee | 371 | |
1da177e4 LT |
372 | init_pushpull(&rs.pp, cdata_in, srclen, 0, 0); |
373 | init_decode(&rs, bit_divider, bits); | |
182ec4ee | 374 | |
1da177e4 LT |
375 | while (outpos < destlen) { |
376 | page_out[outpos++] = in_byte(&rs); | |
377 | } | |
182ec4ee | 378 | } |
1da177e4 LT |
379 | |
380 | ||
75c96f85 AB |
381 | static int jffs2_rubinmips_decompress(unsigned char *data_in, |
382 | unsigned char *cpage_out, | |
383 | uint32_t sourcelen, uint32_t dstlen, | |
384 | void *model) | |
1da177e4 LT |
385 | { |
386 | rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen); | |
387 | return 0; | |
388 | } | |
389 | ||
75c96f85 AB |
390 | static int jffs2_dynrubin_decompress(unsigned char *data_in, |
391 | unsigned char *cpage_out, | |
392 | uint32_t sourcelen, uint32_t dstlen, | |
393 | void *model) | |
1da177e4 LT |
394 | { |
395 | int bits[8]; | |
396 | int c; | |
397 | ||
398 | for (c=0; c<8; c++) | |
399 | bits[c] = data_in[c]; | |
400 | ||
401 | rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8, dstlen); | |
402 | return 0; | |
403 | } | |
404 | ||
405 | static struct jffs2_compressor jffs2_rubinmips_comp = { | |
406 | .priority = JFFS2_RUBINMIPS_PRIORITY, | |
407 | .name = "rubinmips", | |
408 | .compr = JFFS2_COMPR_DYNRUBIN, | |
409 | .compress = NULL, /*&jffs2_rubinmips_compress,*/ | |
410 | .decompress = &jffs2_rubinmips_decompress, | |
411 | #ifdef JFFS2_RUBINMIPS_DISABLED | |
412 | .disabled = 1, | |
413 | #else | |
414 | .disabled = 0, | |
415 | #endif | |
416 | }; | |
417 | ||
418 | int jffs2_rubinmips_init(void) | |
419 | { | |
420 | return jffs2_register_compressor(&jffs2_rubinmips_comp); | |
421 | } | |
422 | ||
423 | void jffs2_rubinmips_exit(void) | |
424 | { | |
425 | jffs2_unregister_compressor(&jffs2_rubinmips_comp); | |
426 | } | |
427 | ||
428 | static struct jffs2_compressor jffs2_dynrubin_comp = { | |
429 | .priority = JFFS2_DYNRUBIN_PRIORITY, | |
430 | .name = "dynrubin", | |
431 | .compr = JFFS2_COMPR_RUBINMIPS, | |
432 | .compress = jffs2_dynrubin_compress, | |
433 | .decompress = &jffs2_dynrubin_decompress, | |
434 | #ifdef JFFS2_DYNRUBIN_DISABLED | |
435 | .disabled = 1, | |
436 | #else | |
437 | .disabled = 0, | |
438 | #endif | |
439 | }; | |
440 | ||
441 | int jffs2_dynrubin_init(void) | |
442 | { | |
443 | return jffs2_register_compressor(&jffs2_dynrubin_comp); | |
444 | } | |
445 | ||
446 | void jffs2_dynrubin_exit(void) | |
447 | { | |
448 | jffs2_unregister_compressor(&jffs2_dynrubin_comp); | |
449 | } |