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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14
15 #include <linux/string.h>
16 #include <linux/types.h>
17 #include <linux/jffs2.h>
18 #include <linux/errno.h>
19 #include "compr.h"
20
21
22 #define RUBIN_REG_SIZE 16
23 #define UPPER_BIT_RUBIN (((long) 1)<<(RUBIN_REG_SIZE-1))
24 #define LOWER_BITS_RUBIN ((((long) 1)<<(RUBIN_REG_SIZE-1))-1)
25
26
27 #define BIT_DIVIDER_MIPS 1043
28 static int bits_mips[8] = { 277, 249, 290, 267, 229, 341, 212, 241};
29
30 struct pushpull {
31 unsigned char *buf;
32 unsigned int buflen;
33 unsigned int ofs;
34 unsigned int reserve;
35 };
36
37 struct rubin_state {
38 unsigned long p;
39 unsigned long q;
40 unsigned long rec_q;
41 long bit_number;
42 struct pushpull pp;
43 int bit_divider;
44 int bits[8];
45 };
46
init_pushpull(struct pushpull * pp,char * buf,unsigned buflen,unsigned ofs,unsigned reserve)47 static inline void init_pushpull(struct pushpull *pp, char *buf,
48 unsigned buflen, unsigned ofs,
49 unsigned reserve)
50 {
51 pp->buf = buf;
52 pp->buflen = buflen;
53 pp->ofs = ofs;
54 pp->reserve = reserve;
55 }
56
pushbit(struct pushpull * pp,int bit,int use_reserved)57 static inline int pushbit(struct pushpull *pp, int bit, int use_reserved)
58 {
59 if (pp->ofs >= pp->buflen - (use_reserved?0:pp->reserve))
60 return -ENOSPC;
61
62 if (bit)
63 pp->buf[pp->ofs >> 3] |= (1<<(7-(pp->ofs & 7)));
64 else
65 pp->buf[pp->ofs >> 3] &= ~(1<<(7-(pp->ofs & 7)));
66
67 pp->ofs++;
68
69 return 0;
70 }
71
pushedbits(struct pushpull * pp)72 static inline int pushedbits(struct pushpull *pp)
73 {
74 return pp->ofs;
75 }
76
pullbit(struct pushpull * pp)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
init_rubin(struct rubin_state * rs,int div,int * bits)88 static void init_rubin(struct rubin_state *rs, int div, int *bits)
89 {
90 int c;
91
92 rs->q = 0;
93 rs->p = (long) (2 * UPPER_BIT_RUBIN);
94 rs->bit_number = (long) 0;
95 rs->bit_divider = div;
96
97 for (c=0; c<8; c++)
98 rs->bits[c] = bits[c];
99 }
100
101
encode(struct rubin_state * rs,long A,long B,int symbol)102 static int encode(struct rubin_state *rs, long A, long B, int symbol)
103 {
104
105 long i0, i1;
106 int ret;
107
108 while ((rs->q >= UPPER_BIT_RUBIN) ||
109 ((rs->p + rs->q) <= UPPER_BIT_RUBIN)) {
110 rs->bit_number++;
111
112 ret = pushbit(&rs->pp, (rs->q & UPPER_BIT_RUBIN) ? 1 : 0, 0);
113 if (ret)
114 return ret;
115 rs->q &= LOWER_BITS_RUBIN;
116 rs->q <<= 1;
117 rs->p <<= 1;
118 }
119 i0 = A * rs->p / (A + B);
120 if (i0 <= 0)
121 i0 = 1;
122
123 if (i0 >= rs->p)
124 i0 = rs->p - 1;
125
126 i1 = rs->p - i0;
127
128 if (symbol == 0)
129 rs->p = i0;
130 else {
131 rs->p = i1;
132 rs->q += i0;
133 }
134 return 0;
135 }
136
137
end_rubin(struct rubin_state * rs)138 static void end_rubin(struct rubin_state *rs)
139 {
140
141 int i;
142
143 for (i = 0; i < RUBIN_REG_SIZE; i++) {
144 pushbit(&rs->pp, (UPPER_BIT_RUBIN & rs->q) ? 1 : 0, 1);
145 rs->q &= LOWER_BITS_RUBIN;
146 rs->q <<= 1;
147 }
148 }
149
150
init_decode(struct rubin_state * rs,int div,int * bits)151 static void init_decode(struct rubin_state *rs, int div, int *bits)
152 {
153 init_rubin(rs, div, bits);
154
155 /* behalve lower */
156 rs->rec_q = 0;
157
158 for (rs->bit_number = 0; rs->bit_number++ < RUBIN_REG_SIZE;
159 rs->rec_q = rs->rec_q * 2 + (long) (pullbit(&rs->pp)))
160 ;
161 }
162
__do_decode(struct rubin_state * rs,unsigned long p,unsigned long q)163 static void __do_decode(struct rubin_state *rs, unsigned long p,
164 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
decode(struct rubin_state * rs,long A,long B)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 threshold = rs->q + i0;
217 symbol = rs->rec_q >= threshold;
218 if (rs->rec_q >= threshold) {
219 rs->q += i0;
220 i0 = rs->p - i0;
221 }
222
223 rs->p = i0;
224
225 return symbol;
226 }
227
228
229
out_byte(struct rubin_state * rs,unsigned char byte)230 static int out_byte(struct rubin_state *rs, unsigned char byte)
231 {
232 int i, ret;
233 struct rubin_state rs_copy;
234 rs_copy = *rs;
235
236 for (i=0; i<8; i++) {
237 ret = encode(rs, rs->bit_divider-rs->bits[i],
238 rs->bits[i], byte & 1);
239 if (ret) {
240 /* Failed. Restore old state */
241 *rs = rs_copy;
242 return ret;
243 }
244 byte >>= 1 ;
245 }
246 return 0;
247 }
248
in_byte(struct rubin_state * rs)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],
255 rs->bits[i]) << i;
256
257 return result;
258 }
259
260
261
rubin_do_compress(int bit_divider,int * bits,unsigned char * data_in,unsigned char * cpage_out,uint32_t * sourcelen,uint32_t * dstlen)262 static int rubin_do_compress(int bit_divider, int *bits, unsigned char *data_in,
263 unsigned char *cpage_out, uint32_t *sourcelen,
264 uint32_t *dstlen)
265 {
266 int outpos = 0;
267 int pos=0;
268 struct rubin_state rs;
269
270 init_pushpull(&rs.pp, cpage_out, *dstlen * 8, 0, 32);
271
272 init_rubin(&rs, bit_divider, bits);
273
274 while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos]))
275 pos++;
276
277 end_rubin(&rs);
278
279 if (outpos > pos) {
280 /* We failed */
281 return -1;
282 }
283
284 /* Tell the caller how much we managed to compress,
285 * and how much space it took */
286
287 outpos = (pushedbits(&rs.pp)+7)/8;
288
289 if (outpos >= pos)
290 return -1; /* We didn't actually compress */
291 *sourcelen = pos;
292 *dstlen = outpos;
293 return 0;
294 }
295 #if 0
296 /* _compress returns the compressed size, -1 if bigger */
297 int jffs2_rubinmips_compress(unsigned char *data_in, unsigned char *cpage_out,
298 uint32_t *sourcelen, uint32_t *dstlen)
299 {
300 return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in,
301 cpage_out, sourcelen, dstlen);
302 }
303 #endif
jffs2_dynrubin_compress(unsigned char * data_in,unsigned char * cpage_out,uint32_t * sourcelen,uint32_t * dstlen)304 static int jffs2_dynrubin_compress(unsigned char *data_in,
305 unsigned char *cpage_out,
306 uint32_t *sourcelen, uint32_t *dstlen)
307 {
308 int bits[8];
309 unsigned char histo[256];
310 int i;
311 int ret;
312 uint32_t mysrclen, mydstlen;
313
314 mysrclen = *sourcelen;
315 mydstlen = *dstlen - 8;
316
317 if (*dstlen <= 12)
318 return -1;
319
320 memset(histo, 0, 256);
321 for (i=0; i<mysrclen; i++)
322 histo[data_in[i]]++;
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,
351 &mydstlen);
352 if (ret)
353 return ret;
354
355 /* Add back the 8 bytes we took for the probabilities */
356 mydstlen += 8;
357
358 if (mysrclen <= mydstlen) {
359 /* We compressed */
360 return -1;
361 }
362
363 *sourcelen = mysrclen;
364 *dstlen = mydstlen;
365 return 0;
366 }
367
rubin_do_decompress(int bit_divider,int * bits,unsigned char * cdata_in,unsigned char * page_out,uint32_t srclen,uint32_t destlen)368 static void rubin_do_decompress(int bit_divider, int *bits,
369 unsigned char *cdata_in,
370 unsigned char *page_out, uint32_t srclen,
371 uint32_t destlen)
372 {
373 int outpos = 0;
374 struct rubin_state rs;
375
376 init_pushpull(&rs.pp, cdata_in, srclen, 0, 0);
377 init_decode(&rs, bit_divider, bits);
378
379 while (outpos < destlen)
380 page_out[outpos++] = in_byte(&rs);
381 }
382
383
jffs2_rubinmips_decompress(unsigned char * data_in,unsigned char * cpage_out,uint32_t sourcelen,uint32_t dstlen)384 static int jffs2_rubinmips_decompress(unsigned char *data_in,
385 unsigned char *cpage_out,
386 uint32_t sourcelen, uint32_t dstlen)
387 {
388 rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in,
389 cpage_out, sourcelen, dstlen);
390 return 0;
391 }
392
jffs2_dynrubin_decompress(unsigned char * data_in,unsigned char * cpage_out,uint32_t sourcelen,uint32_t dstlen)393 static int jffs2_dynrubin_decompress(unsigned char *data_in,
394 unsigned char *cpage_out,
395 uint32_t sourcelen, uint32_t dstlen)
396 {
397 int bits[8];
398 int c;
399
400 for (c=0; c<8; c++)
401 bits[c] = data_in[c];
402
403 rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8,
404 dstlen);
405 return 0;
406 }
407
408 static struct jffs2_compressor jffs2_rubinmips_comp = {
409 .priority = JFFS2_RUBINMIPS_PRIORITY,
410 .name = "rubinmips",
411 .compr = JFFS2_COMPR_DYNRUBIN,
412 .compress = NULL, /*&jffs2_rubinmips_compress,*/
413 .decompress = &jffs2_rubinmips_decompress,
414 #ifdef JFFS2_RUBINMIPS_DISABLED
415 .disabled = 1,
416 #else
417 .disabled = 0,
418 #endif
419 };
420
jffs2_rubinmips_init(void)421 int jffs2_rubinmips_init(void)
422 {
423 return jffs2_register_compressor(&jffs2_rubinmips_comp);
424 }
425
jffs2_rubinmips_exit(void)426 void jffs2_rubinmips_exit(void)
427 {
428 jffs2_unregister_compressor(&jffs2_rubinmips_comp);
429 }
430
431 static struct jffs2_compressor jffs2_dynrubin_comp = {
432 .priority = JFFS2_DYNRUBIN_PRIORITY,
433 .name = "dynrubin",
434 .compr = JFFS2_COMPR_RUBINMIPS,
435 .compress = jffs2_dynrubin_compress,
436 .decompress = &jffs2_dynrubin_decompress,
437 #ifdef JFFS2_DYNRUBIN_DISABLED
438 .disabled = 1,
439 #else
440 .disabled = 0,
441 #endif
442 };
443
jffs2_dynrubin_init(void)444 int jffs2_dynrubin_init(void)
445 {
446 return jffs2_register_compressor(&jffs2_dynrubin_comp);
447 }
448
jffs2_dynrubin_exit(void)449 void jffs2_dynrubin_exit(void)
450 {
451 jffs2_unregister_compressor(&jffs2_dynrubin_comp);
452 }
453