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 | ||
24 | struct rubin_state { | |
25 | unsigned long p; | |
26 | unsigned long q; | |
27 | unsigned long rec_q; | |
28 | long bit_number; | |
29 | struct pushpull pp; | |
30 | int bit_divider; | |
31 | int bits[8]; | |
32 | }; | |
33 | ||
34 | #define BIT_DIVIDER_MIPS 1043 | |
35 | static int bits_mips[8] = { 277,249,290,267,229,341,212,241}; /* mips32 */ | |
36 | ||
37 | #include <linux/errno.h> | |
38 | ||
39 | struct pushpull { | |
40 | unsigned char *buf; | |
41 | unsigned int buflen; | |
42 | unsigned int ofs; | |
43 | unsigned int reserve; | |
44 | }; | |
45 | ||
46 | ||
47 | static inline void init_pushpull(struct pushpull *pp, char *buf, unsigned buflen, unsigned ofs, 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 | ||
61 | if (bit) { | |
62 | pp->buf[pp->ofs >> 3] |= (1<<(7-(pp->ofs &7))); | |
63 | } | |
64 | else { | |
65 | pp->buf[pp->ofs >> 3] &= ~(1<<(7-(pp->ofs &7))); | |
66 | } | |
67 | pp->ofs++; | |
68 | ||
69 | return 0; | |
70 | } | |
71 | ||
72 | static inline int pushedbits(struct pushpull *pp) | |
73 | { | |
74 | return pp->ofs; | |
75 | } | |
76 | ||
77 | static inline int pullbit(struct pushpull *pp) | |
78 | { | |
79 | int bit; | |
80 | ||
81 | bit = (pp->buf[pp->ofs >> 3] >> (7-(pp->ofs & 7))) & 1; | |
82 | ||
83 | pp->ofs++; | |
84 | return bit; | |
85 | } | |
86 | ||
87 | static inline int pulledbits(struct pushpull *pp) | |
88 | { | |
89 | return pp->ofs; | |
90 | } | |
91 | ||
92 | ||
1da177e4 | 93 | static void init_rubin(struct rubin_state *rs, int div, int *bits) |
182ec4ee | 94 | { |
1da177e4 LT |
95 | int c; |
96 | ||
97 | rs->q = 0; | |
98 | rs->p = (long) (2 * UPPER_BIT_RUBIN); | |
99 | rs->bit_number = (long) 0; | |
100 | rs->bit_divider = div; | |
101 | for (c=0; c<8; c++) | |
102 | rs->bits[c] = bits[c]; | |
103 | } | |
104 | ||
105 | ||
106 | static int encode(struct rubin_state *rs, long A, long B, int symbol) | |
107 | { | |
108 | ||
109 | long i0, i1; | |
110 | int ret; | |
111 | ||
112 | while ((rs->q >= UPPER_BIT_RUBIN) || ((rs->p + rs->q) <= UPPER_BIT_RUBIN)) { | |
113 | rs->bit_number++; | |
182ec4ee | 114 | |
1da177e4 LT |
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) | |
182ec4ee | 142 | { |
1da177e4 LT |
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 | { | |
182ec4ee | 156 | init_rubin(rs, div, bits); |
1da177e4 LT |
157 | |
158 | /* behalve lower */ | |
159 | rs->rec_q = 0; | |
160 | ||
161 | for (rs->bit_number = 0; rs->bit_number++ < RUBIN_REG_SIZE; rs->rec_q = rs->rec_q * 2 + (long) (pullbit(&rs->pp))) | |
162 | ; | |
163 | } | |
164 | ||
165 | static void __do_decode(struct rubin_state *rs, unsigned long p, unsigned long q) | |
166 | { | |
167 | register unsigned long lower_bits_rubin = LOWER_BITS_RUBIN; | |
168 | unsigned long rec_q; | |
169 | int c, bits = 0; | |
170 | ||
171 | /* | |
172 | * First, work out how many bits we need from the input stream. | |
173 | * Note that we have already done the initial check on this | |
174 | * loop prior to calling this function. | |
175 | */ | |
176 | do { | |
177 | bits++; | |
178 | q &= lower_bits_rubin; | |
179 | q <<= 1; | |
180 | p <<= 1; | |
181 | } while ((q >= UPPER_BIT_RUBIN) || ((p + q) <= UPPER_BIT_RUBIN)); | |
182 | ||
183 | rs->p = p; | |
184 | rs->q = q; | |
185 | ||
186 | rs->bit_number += bits; | |
187 | ||
188 | /* | |
189 | * Now get the bits. We really want this to be "get n bits". | |
190 | */ | |
191 | rec_q = rs->rec_q; | |
192 | do { | |
193 | c = pullbit(&rs->pp); | |
194 | rec_q &= lower_bits_rubin; | |
195 | rec_q <<= 1; | |
196 | rec_q += c; | |
197 | } while (--bits); | |
198 | rs->rec_q = rec_q; | |
199 | } | |
200 | ||
201 | static int decode(struct rubin_state *rs, long A, long B) | |
202 | { | |
203 | unsigned long p = rs->p, q = rs->q; | |
204 | long i0, threshold; | |
205 | int symbol; | |
206 | ||
207 | if (q >= UPPER_BIT_RUBIN || ((p + q) <= UPPER_BIT_RUBIN)) | |
208 | __do_decode(rs, p, q); | |
209 | ||
210 | i0 = A * rs->p / (A + B); | |
211 | if (i0 <= 0) { | |
212 | i0 = 1; | |
213 | } | |
214 | if (i0 >= rs->p) { | |
215 | i0 = rs->p - 1; | |
216 | } | |
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 | ||
238 | for (i=0;i<8;i++) { | |
239 | ret = encode(rs, rs->bit_divider-rs->bits[i],rs->bits[i],byte&1); | |
240 | if (ret) { | |
241 | /* Failed. Restore old state */ | |
242 | *rs = rs_copy; | |
243 | return ret; | |
244 | } | |
245 | byte=byte>>1; | |
246 | } | |
247 | return 0; | |
248 | } | |
249 | ||
250 | static int in_byte(struct rubin_state *rs) | |
251 | { | |
252 | int i, result = 0, bit_divider = rs->bit_divider; | |
253 | ||
254 | for (i = 0; i < 8; i++) | |
255 | result |= decode(rs, bit_divider - rs->bits[i], rs->bits[i]) << i; | |
256 | ||
257 | return result; | |
258 | } | |
259 | ||
260 | ||
261 | ||
182ec4ee | 262 | static int rubin_do_compress(int bit_divider, int *bits, unsigned char *data_in, |
1da177e4 LT |
263 | unsigned char *cpage_out, uint32_t *sourcelen, uint32_t *dstlen) |
264 | { | |
265 | int outpos = 0; | |
266 | int pos=0; | |
267 | struct rubin_state rs; | |
268 | ||
269 | init_pushpull(&rs.pp, cpage_out, *dstlen * 8, 0, 32); | |
270 | ||
271 | init_rubin(&rs, bit_divider, bits); | |
182ec4ee | 272 | |
1da177e4 LT |
273 | while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos])) |
274 | pos++; | |
182ec4ee | 275 | |
1da177e4 LT |
276 | end_rubin(&rs); |
277 | ||
278 | if (outpos > pos) { | |
279 | /* We failed */ | |
280 | return -1; | |
281 | } | |
182ec4ee TG |
282 | |
283 | /* Tell the caller how much we managed to compress, | |
1da177e4 | 284 | * and how much space it took */ |
182ec4ee | 285 | |
1da177e4 | 286 | outpos = (pushedbits(&rs.pp)+7)/8; |
182ec4ee | 287 | |
1da177e4 LT |
288 | if (outpos >= pos) |
289 | return -1; /* We didn't actually compress */ | |
290 | *sourcelen = pos; | |
291 | *dstlen = outpos; | |
292 | return 0; | |
182ec4ee | 293 | } |
1da177e4 LT |
294 | #if 0 |
295 | /* _compress returns the compressed size, -1 if bigger */ | |
182ec4ee | 296 | int jffs2_rubinmips_compress(unsigned char *data_in, unsigned char *cpage_out, |
1da177e4 LT |
297 | uint32_t *sourcelen, uint32_t *dstlen, void *model) |
298 | { | |
299 | return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen); | |
300 | } | |
301 | #endif | |
75c96f85 AB |
302 | static int jffs2_dynrubin_compress(unsigned char *data_in, |
303 | unsigned char *cpage_out, | |
304 | uint32_t *sourcelen, uint32_t *dstlen, | |
305 | void *model) | |
1da177e4 LT |
306 | { |
307 | int bits[8]; | |
308 | unsigned char histo[256]; | |
309 | int i; | |
310 | int ret; | |
311 | uint32_t mysrclen, mydstlen; | |
312 | ||
313 | mysrclen = *sourcelen; | |
314 | mydstlen = *dstlen - 8; | |
315 | ||
316 | if (*dstlen <= 12) | |
317 | return -1; | |
318 | ||
319 | memset(histo, 0, 256); | |
320 | for (i=0; i<mysrclen; i++) { | |
321 | histo[data_in[i]]++; | |
322 | } | |
323 | memset(bits, 0, sizeof(int)*8); | |
324 | for (i=0; i<256; i++) { | |
325 | if (i&128) | |
326 | bits[7] += histo[i]; | |
327 | if (i&64) | |
328 | bits[6] += histo[i]; | |
329 | if (i&32) | |
330 | bits[5] += histo[i]; | |
331 | if (i&16) | |
332 | bits[4] += histo[i]; | |
333 | if (i&8) | |
334 | bits[3] += histo[i]; | |
335 | if (i&4) | |
336 | bits[2] += histo[i]; | |
337 | if (i&2) | |
338 | bits[1] += histo[i]; | |
339 | if (i&1) | |
340 | bits[0] += histo[i]; | |
341 | } | |
342 | ||
343 | for (i=0; i<8; i++) { | |
344 | bits[i] = (bits[i] * 256) / mysrclen; | |
345 | if (!bits[i]) bits[i] = 1; | |
346 | if (bits[i] > 255) bits[i] = 255; | |
347 | cpage_out[i] = bits[i]; | |
348 | } | |
349 | ||
350 | ret = rubin_do_compress(256, bits, data_in, cpage_out+8, &mysrclen, &mydstlen); | |
182ec4ee | 351 | if (ret) |
1da177e4 LT |
352 | return ret; |
353 | ||
354 | /* Add back the 8 bytes we took for the probabilities */ | |
355 | mydstlen += 8; | |
356 | ||
357 | if (mysrclen <= mydstlen) { | |
358 | /* We compressed */ | |
359 | return -1; | |
360 | } | |
361 | ||
362 | *sourcelen = mysrclen; | |
363 | *dstlen = mydstlen; | |
364 | return 0; | |
365 | } | |
366 | ||
182ec4ee | 367 | static void rubin_do_decompress(int bit_divider, int *bits, unsigned char *cdata_in, |
1da177e4 LT |
368 | unsigned char *page_out, uint32_t srclen, uint32_t destlen) |
369 | { | |
370 | int outpos = 0; | |
371 | struct rubin_state rs; | |
182ec4ee | 372 | |
1da177e4 LT |
373 | init_pushpull(&rs.pp, cdata_in, srclen, 0, 0); |
374 | init_decode(&rs, bit_divider, bits); | |
182ec4ee | 375 | |
1da177e4 LT |
376 | while (outpos < destlen) { |
377 | page_out[outpos++] = in_byte(&rs); | |
378 | } | |
182ec4ee | 379 | } |
1da177e4 LT |
380 | |
381 | ||
75c96f85 AB |
382 | static int jffs2_rubinmips_decompress(unsigned char *data_in, |
383 | unsigned char *cpage_out, | |
384 | uint32_t sourcelen, uint32_t dstlen, | |
385 | void *model) | |
1da177e4 LT |
386 | { |
387 | rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen); | |
388 | return 0; | |
389 | } | |
390 | ||
75c96f85 AB |
391 | static int jffs2_dynrubin_decompress(unsigned char *data_in, |
392 | unsigned char *cpage_out, | |
393 | uint32_t sourcelen, uint32_t dstlen, | |
394 | void *model) | |
1da177e4 LT |
395 | { |
396 | int bits[8]; | |
397 | int c; | |
398 | ||
399 | for (c=0; c<8; c++) | |
400 | bits[c] = data_in[c]; | |
401 | ||
402 | rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8, dstlen); | |
403 | return 0; | |
404 | } | |
405 | ||
406 | static struct jffs2_compressor jffs2_rubinmips_comp = { | |
407 | .priority = JFFS2_RUBINMIPS_PRIORITY, | |
408 | .name = "rubinmips", | |
409 | .compr = JFFS2_COMPR_DYNRUBIN, | |
410 | .compress = NULL, /*&jffs2_rubinmips_compress,*/ | |
411 | .decompress = &jffs2_rubinmips_decompress, | |
412 | #ifdef JFFS2_RUBINMIPS_DISABLED | |
413 | .disabled = 1, | |
414 | #else | |
415 | .disabled = 0, | |
416 | #endif | |
417 | }; | |
418 | ||
419 | int jffs2_rubinmips_init(void) | |
420 | { | |
421 | return jffs2_register_compressor(&jffs2_rubinmips_comp); | |
422 | } | |
423 | ||
424 | void jffs2_rubinmips_exit(void) | |
425 | { | |
426 | jffs2_unregister_compressor(&jffs2_rubinmips_comp); | |
427 | } | |
428 | ||
429 | static struct jffs2_compressor jffs2_dynrubin_comp = { | |
430 | .priority = JFFS2_DYNRUBIN_PRIORITY, | |
431 | .name = "dynrubin", | |
432 | .compr = JFFS2_COMPR_RUBINMIPS, | |
433 | .compress = jffs2_dynrubin_compress, | |
434 | .decompress = &jffs2_dynrubin_decompress, | |
435 | #ifdef JFFS2_DYNRUBIN_DISABLED | |
436 | .disabled = 1, | |
437 | #else | |
438 | .disabled = 0, | |
439 | #endif | |
440 | }; | |
441 | ||
442 | int jffs2_dynrubin_init(void) | |
443 | { | |
444 | return jffs2_register_compressor(&jffs2_dynrubin_comp); | |
445 | } | |
446 | ||
447 | void jffs2_dynrubin_exit(void) | |
448 | { | |
449 | jffs2_unregister_compressor(&jffs2_dynrubin_comp); | |
450 | } |