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 | 24 | #define BIT_DIVIDER_MIPS 1043 |
0bc4382a | 25 | static int bits_mips[8] = { 277, 249, 290, 267, 229, 341, 212, 241}; |
c00c310e DW |
26 | |
27 | struct pushpull { | |
28 | unsigned char *buf; | |
29 | unsigned int buflen; | |
30 | unsigned int ofs; | |
31 | unsigned int reserve; | |
32 | }; | |
33 | ||
f6449f4e AM |
34 | struct rubin_state { |
35 | unsigned long p; | |
36 | unsigned long q; | |
37 | unsigned long rec_q; | |
38 | long bit_number; | |
39 | struct pushpull pp; | |
40 | int bit_divider; | |
41 | int bits[8]; | |
42 | }; | |
c00c310e | 43 | |
0bc4382a DW |
44 | static inline void init_pushpull(struct pushpull *pp, char *buf, |
45 | unsigned buflen, unsigned ofs, | |
46 | unsigned reserve) | |
c00c310e DW |
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 | { | |
0bc4382a | 56 | if (pp->ofs >= pp->buflen - (use_reserved?0:pp->reserve)) |
c00c310e | 57 | return -ENOSPC; |
c00c310e | 58 | |
0bc4382a DW |
59 | if (bit) |
60 | pp->buf[pp->ofs >> 3] |= (1<<(7-(pp->ofs & 7))); | |
61 | else | |
62 | pp->buf[pp->ofs >> 3] &= ~(1<<(7-(pp->ofs & 7))); | |
63 | ||
c00c310e DW |
64 | pp->ofs++; |
65 | ||
66 | return 0; | |
67 | } | |
68 | ||
69 | static inline int pushedbits(struct pushpull *pp) | |
70 | { | |
71 | return pp->ofs; | |
72 | } | |
73 | ||
74 | static inline int pullbit(struct pushpull *pp) | |
75 | { | |
76 | int bit; | |
77 | ||
78 | bit = (pp->buf[pp->ofs >> 3] >> (7-(pp->ofs & 7))) & 1; | |
79 | ||
80 | pp->ofs++; | |
81 | return bit; | |
82 | } | |
83 | ||
84 | static inline int pulledbits(struct pushpull *pp) | |
85 | { | |
86 | return pp->ofs; | |
87 | } | |
88 | ||
89 | ||
1da177e4 | 90 | static void init_rubin(struct rubin_state *rs, int div, int *bits) |
182ec4ee | 91 | { |
1da177e4 LT |
92 | int c; |
93 | ||
94 | rs->q = 0; | |
95 | rs->p = (long) (2 * UPPER_BIT_RUBIN); | |
96 | rs->bit_number = (long) 0; | |
97 | rs->bit_divider = div; | |
0bc4382a | 98 | |
1da177e4 LT |
99 | for (c=0; c<8; c++) |
100 | rs->bits[c] = bits[c]; | |
101 | } | |
102 | ||
103 | ||
104 | static int encode(struct rubin_state *rs, long A, long B, int symbol) | |
105 | { | |
106 | ||
107 | long i0, i1; | |
108 | int ret; | |
109 | ||
0bc4382a DW |
110 | while ((rs->q >= UPPER_BIT_RUBIN) || |
111 | ((rs->p + rs->q) <= UPPER_BIT_RUBIN)) { | |
1da177e4 | 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); | |
0bc4382a | 122 | if (i0 <= 0) |
1da177e4 | 123 | i0 = 1; |
0bc4382a DW |
124 | |
125 | if (i0 >= rs->p) | |
1da177e4 | 126 | i0 = rs->p - 1; |
0bc4382a | 127 | |
1da177e4 LT |
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 | ||
0bc4382a DW |
160 | for (rs->bit_number = 0; rs->bit_number++ < RUBIN_REG_SIZE; |
161 | rs->rec_q = rs->rec_q * 2 + (long) (pullbit(&rs->pp))) | |
1da177e4 LT |
162 | ; |
163 | } | |
164 | ||
0bc4382a DW |
165 | static void __do_decode(struct rubin_state *rs, unsigned long p, |
166 | unsigned long q) | |
1da177e4 LT |
167 | { |
168 | register unsigned long lower_bits_rubin = LOWER_BITS_RUBIN; | |
169 | unsigned long rec_q; | |
170 | int c, bits = 0; | |
171 | ||
172 | /* | |
173 | * First, work out how many bits we need from the input stream. | |
174 | * Note that we have already done the initial check on this | |
175 | * loop prior to calling this function. | |
176 | */ | |
177 | do { | |
178 | bits++; | |
179 | q &= lower_bits_rubin; | |
180 | q <<= 1; | |
181 | p <<= 1; | |
182 | } while ((q >= UPPER_BIT_RUBIN) || ((p + q) <= UPPER_BIT_RUBIN)); | |
183 | ||
184 | rs->p = p; | |
185 | rs->q = q; | |
186 | ||
187 | rs->bit_number += bits; | |
188 | ||
189 | /* | |
190 | * Now get the bits. We really want this to be "get n bits". | |
191 | */ | |
192 | rec_q = rs->rec_q; | |
193 | do { | |
194 | c = pullbit(&rs->pp); | |
195 | rec_q &= lower_bits_rubin; | |
196 | rec_q <<= 1; | |
197 | rec_q += c; | |
198 | } while (--bits); | |
199 | rs->rec_q = rec_q; | |
200 | } | |
201 | ||
202 | static int decode(struct rubin_state *rs, long A, long B) | |
203 | { | |
204 | unsigned long p = rs->p, q = rs->q; | |
205 | long i0, threshold; | |
206 | int symbol; | |
207 | ||
208 | if (q >= UPPER_BIT_RUBIN || ((p + q) <= UPPER_BIT_RUBIN)) | |
209 | __do_decode(rs, p, q); | |
210 | ||
211 | i0 = A * rs->p / (A + B); | |
0bc4382a | 212 | if (i0 <= 0) |
1da177e4 | 213 | i0 = 1; |
0bc4382a DW |
214 | |
215 | if (i0 >= rs->p) | |
1da177e4 | 216 | i0 = rs->p - 1; |
1da177e4 LT |
217 | |
218 | threshold = rs->q + i0; | |
219 | symbol = rs->rec_q >= threshold; | |
220 | if (rs->rec_q >= threshold) { | |
221 | rs->q += i0; | |
222 | i0 = rs->p - i0; | |
223 | } | |
224 | ||
225 | rs->p = i0; | |
226 | ||
227 | return symbol; | |
228 | } | |
229 | ||
230 | ||
231 | ||
232 | static int out_byte(struct rubin_state *rs, unsigned char byte) | |
233 | { | |
234 | int i, ret; | |
235 | struct rubin_state rs_copy; | |
236 | rs_copy = *rs; | |
237 | ||
0bc4382a DW |
238 | for (i=0; i<8; i++) { |
239 | ret = encode(rs, rs->bit_divider-rs->bits[i], | |
240 | rs->bits[i], byte & 1); | |
1da177e4 LT |
241 | if (ret) { |
242 | /* Failed. Restore old state */ | |
243 | *rs = rs_copy; | |
244 | return ret; | |
245 | } | |
0bc4382a | 246 | byte >>= 1 ; |
1da177e4 LT |
247 | } |
248 | return 0; | |
249 | } | |
250 | ||
251 | static int in_byte(struct rubin_state *rs) | |
252 | { | |
253 | int i, result = 0, bit_divider = rs->bit_divider; | |
254 | ||
255 | for (i = 0; i < 8; i++) | |
0bc4382a DW |
256 | result |= decode(rs, bit_divider - rs->bits[i], |
257 | rs->bits[i]) << i; | |
1da177e4 LT |
258 | |
259 | return result; | |
260 | } | |
261 | ||
262 | ||
263 | ||
182ec4ee | 264 | static int rubin_do_compress(int bit_divider, int *bits, unsigned char *data_in, |
0bc4382a DW |
265 | unsigned char *cpage_out, uint32_t *sourcelen, |
266 | uint32_t *dstlen) | |
1da177e4 LT |
267 | { |
268 | int outpos = 0; | |
269 | int pos=0; | |
270 | struct rubin_state rs; | |
271 | ||
272 | init_pushpull(&rs.pp, cpage_out, *dstlen * 8, 0, 32); | |
273 | ||
274 | init_rubin(&rs, bit_divider, bits); | |
182ec4ee | 275 | |
1da177e4 LT |
276 | while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos])) |
277 | pos++; | |
182ec4ee | 278 | |
1da177e4 LT |
279 | end_rubin(&rs); |
280 | ||
281 | if (outpos > pos) { | |
282 | /* We failed */ | |
283 | return -1; | |
284 | } | |
182ec4ee TG |
285 | |
286 | /* Tell the caller how much we managed to compress, | |
1da177e4 | 287 | * and how much space it took */ |
182ec4ee | 288 | |
1da177e4 | 289 | outpos = (pushedbits(&rs.pp)+7)/8; |
182ec4ee | 290 | |
1da177e4 LT |
291 | if (outpos >= pos) |
292 | return -1; /* We didn't actually compress */ | |
293 | *sourcelen = pos; | |
294 | *dstlen = outpos; | |
295 | return 0; | |
182ec4ee | 296 | } |
1da177e4 LT |
297 | #if 0 |
298 | /* _compress returns the compressed size, -1 if bigger */ | |
182ec4ee | 299 | int jffs2_rubinmips_compress(unsigned char *data_in, unsigned char *cpage_out, |
1da177e4 LT |
300 | uint32_t *sourcelen, uint32_t *dstlen, void *model) |
301 | { | |
0bc4382a DW |
302 | return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in, |
303 | cpage_out, sourcelen, dstlen); | |
1da177e4 LT |
304 | } |
305 | #endif | |
75c96f85 AB |
306 | static int jffs2_dynrubin_compress(unsigned char *data_in, |
307 | unsigned char *cpage_out, | |
308 | uint32_t *sourcelen, uint32_t *dstlen, | |
309 | void *model) | |
1da177e4 LT |
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); | |
0bc4382a | 324 | for (i=0; i<mysrclen; i++) |
1da177e4 | 325 | histo[data_in[i]]++; |
1da177e4 LT |
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 | ||
0bc4382a DW |
353 | ret = rubin_do_compress(256, bits, data_in, cpage_out+8, &mysrclen, |
354 | &mydstlen); | |
182ec4ee | 355 | if (ret) |
1da177e4 LT |
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 | ||
0bc4382a DW |
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) | |
1da177e4 LT |
375 | { |
376 | int outpos = 0; | |
377 | struct rubin_state rs; | |
182ec4ee | 378 | |
1da177e4 LT |
379 | init_pushpull(&rs.pp, cdata_in, srclen, 0, 0); |
380 | init_decode(&rs, bit_divider, bits); | |
182ec4ee | 381 | |
0bc4382a | 382 | while (outpos < destlen) |
1da177e4 | 383 | page_out[outpos++] = in_byte(&rs); |
182ec4ee | 384 | } |
1da177e4 LT |
385 | |
386 | ||
75c96f85 AB |
387 | static int jffs2_rubinmips_decompress(unsigned char *data_in, |
388 | unsigned char *cpage_out, | |
389 | uint32_t sourcelen, uint32_t dstlen, | |
390 | void *model) | |
1da177e4 | 391 | { |
0bc4382a DW |
392 | rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in, |
393 | cpage_out, sourcelen, dstlen); | |
ef53cb02 | 394 | return 0; |
1da177e4 LT |
395 | } |
396 | ||
75c96f85 AB |
397 | static int jffs2_dynrubin_decompress(unsigned char *data_in, |
398 | unsigned char *cpage_out, | |
399 | uint32_t sourcelen, uint32_t dstlen, | |
400 | void *model) | |
1da177e4 LT |
401 | { |
402 | int bits[8]; | |
403 | int c; | |
404 | ||
405 | for (c=0; c<8; c++) | |
406 | bits[c] = data_in[c]; | |
407 | ||
0bc4382a DW |
408 | rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8, |
409 | dstlen); | |
ef53cb02 | 410 | return 0; |
1da177e4 LT |
411 | } |
412 | ||
413 | static struct jffs2_compressor jffs2_rubinmips_comp = { | |
0bc4382a DW |
414 | .priority = JFFS2_RUBINMIPS_PRIORITY, |
415 | .name = "rubinmips", | |
416 | .compr = JFFS2_COMPR_DYNRUBIN, | |
417 | .compress = NULL, /*&jffs2_rubinmips_compress,*/ | |
418 | .decompress = &jffs2_rubinmips_decompress, | |
1da177e4 | 419 | #ifdef JFFS2_RUBINMIPS_DISABLED |
0bc4382a | 420 | .disabled = 1, |
1da177e4 | 421 | #else |
0bc4382a | 422 | .disabled = 0, |
1da177e4 LT |
423 | #endif |
424 | }; | |
425 | ||
426 | int jffs2_rubinmips_init(void) | |
427 | { | |
0bc4382a | 428 | return jffs2_register_compressor(&jffs2_rubinmips_comp); |
1da177e4 LT |
429 | } |
430 | ||
431 | void jffs2_rubinmips_exit(void) | |
432 | { | |
0bc4382a | 433 | jffs2_unregister_compressor(&jffs2_rubinmips_comp); |
1da177e4 LT |
434 | } |
435 | ||
436 | static struct jffs2_compressor jffs2_dynrubin_comp = { | |
0bc4382a DW |
437 | .priority = JFFS2_DYNRUBIN_PRIORITY, |
438 | .name = "dynrubin", | |
439 | .compr = JFFS2_COMPR_RUBINMIPS, | |
440 | .compress = jffs2_dynrubin_compress, | |
441 | .decompress = &jffs2_dynrubin_decompress, | |
1da177e4 | 442 | #ifdef JFFS2_DYNRUBIN_DISABLED |
0bc4382a | 443 | .disabled = 1, |
1da177e4 | 444 | #else |
0bc4382a | 445 | .disabled = 0, |
1da177e4 LT |
446 | #endif |
447 | }; | |
448 | ||
449 | int jffs2_dynrubin_init(void) | |
450 | { | |
0bc4382a | 451 | return jffs2_register_compressor(&jffs2_dynrubin_comp); |
1da177e4 LT |
452 | } |
453 | ||
454 | void jffs2_dynrubin_exit(void) | |
455 | { | |
0bc4382a | 456 | jffs2_unregister_compressor(&jffs2_dynrubin_comp); |
1da177e4 | 457 | } |