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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * JFFS2 -- Journalling Flash File System, Version 2.
3 *
David Woodhousec00c3102007-04-25 14:16:47 +01004 * Copyright © 2001-2007 Red Hat, Inc.
Linus Torvalds1da177e2005-04-16 15:20:36 -07005 *
6 * Created by Arjan van de Ven <arjanv@redhat.com>
7 *
8 * For licensing information, see the file 'LICENCE' in this directory.
9 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070010 */
11
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <linux/string.h>
13#include <linux/types.h>
14#include <linux/jffs2.h>
David Woodhousec00c3102007-04-25 14:16:47 +010015#include <linux/errno.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#include "compr.h"
17
David Woodhousec00c3102007-04-25 14:16:47 +010018
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
David Woodhousec00c3102007-04-25 14:16:47 +010024#define BIT_DIVIDER_MIPS 1043
David Woodhouse0bc43822008-12-10 15:34:49 +000025static int bits_mips[8] = { 277, 249, 290, 267, 229, 341, 212, 241};
David Woodhousec00c3102007-04-25 14:16:47 +010026
27struct pushpull {
28 unsigned char *buf;
29 unsigned int buflen;
30 unsigned int ofs;
31 unsigned int reserve;
32};
33
Andrew Mortonf6449f42007-04-26 07:27:04 +010034struct 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};
David Woodhousec00c3102007-04-25 14:16:47 +010043
David Woodhouse0bc43822008-12-10 15:34:49 +000044static inline void init_pushpull(struct pushpull *pp, char *buf,
45 unsigned buflen, unsigned ofs,
46 unsigned reserve)
David Woodhousec00c3102007-04-25 14:16:47 +010047{
48 pp->buf = buf;
49 pp->buflen = buflen;
50 pp->ofs = ofs;
51 pp->reserve = reserve;
52}
53
54static inline int pushbit(struct pushpull *pp, int bit, int use_reserved)
55{
David Woodhouse0bc43822008-12-10 15:34:49 +000056 if (pp->ofs >= pp->buflen - (use_reserved?0:pp->reserve))
David Woodhousec00c3102007-04-25 14:16:47 +010057 return -ENOSPC;
David Woodhousec00c3102007-04-25 14:16:47 +010058
David Woodhouse0bc43822008-12-10 15:34:49 +000059 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
David Woodhousec00c3102007-04-25 14:16:47 +010064 pp->ofs++;
65
66 return 0;
67}
68
69static inline int pushedbits(struct pushpull *pp)
70{
71 return pp->ofs;
72}
73
74static 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
84static inline int pulledbits(struct pushpull *pp)
85{
86 return pp->ofs;
87}
88
89
Linus Torvalds1da177e2005-04-16 15:20:36 -070090static void init_rubin(struct rubin_state *rs, int div, int *bits)
Thomas Gleixner182ec4e2005-11-07 11:16:07 +000091{
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 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;
David Woodhouse0bc43822008-12-10 15:34:49 +000098
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 for (c=0; c<8; c++)
100 rs->bits[c] = bits[c];
101}
102
103
104static int encode(struct rubin_state *rs, long A, long B, int symbol)
105{
106
107 long i0, i1;
108 int ret;
109
David Woodhouse0bc43822008-12-10 15:34:49 +0000110 while ((rs->q >= UPPER_BIT_RUBIN) ||
111 ((rs->p + rs->q) <= UPPER_BIT_RUBIN)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 rs->bit_number++;
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000113
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 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);
David Woodhouse0bc43822008-12-10 15:34:49 +0000122 if (i0 <= 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 i0 = 1;
David Woodhouse0bc43822008-12-10 15:34:49 +0000124
125 if (i0 >= rs->p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126 i0 = rs->p - 1;
David Woodhouse0bc43822008-12-10 15:34:49 +0000127
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 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
140static void end_rubin(struct rubin_state *rs)
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000141{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142
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
153static void init_decode(struct rubin_state *rs, int div, int *bits)
154{
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000155 init_rubin(rs, div, bits);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156
157 /* behalve lower */
158 rs->rec_q = 0;
159
David Woodhouse0bc43822008-12-10 15:34:49 +0000160 for (rs->bit_number = 0; rs->bit_number++ < RUBIN_REG_SIZE;
161 rs->rec_q = rs->rec_q * 2 + (long) (pullbit(&rs->pp)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 ;
163}
164
David Woodhouse0bc43822008-12-10 15:34:49 +0000165static void __do_decode(struct rubin_state *rs, unsigned long p,
166 unsigned long q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167{
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
202static 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);
David Woodhouse0bc43822008-12-10 15:34:49 +0000212 if (i0 <= 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 i0 = 1;
David Woodhouse0bc43822008-12-10 15:34:49 +0000214
215 if (i0 >= rs->p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 i0 = rs->p - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217
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
232static 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
David Woodhouse0bc43822008-12-10 15:34:49 +0000238 for (i=0; i<8; i++) {
239 ret = encode(rs, rs->bit_divider-rs->bits[i],
240 rs->bits[i], byte & 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241 if (ret) {
242 /* Failed. Restore old state */
243 *rs = rs_copy;
244 return ret;
245 }
David Woodhouse0bc43822008-12-10 15:34:49 +0000246 byte >>= 1 ;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 }
248 return 0;
249}
250
251static 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++)
David Woodhouse0bc43822008-12-10 15:34:49 +0000256 result |= decode(rs, bit_divider - rs->bits[i],
257 rs->bits[i]) << i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258
259 return result;
260}
261
262
263
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000264static int rubin_do_compress(int bit_divider, int *bits, unsigned char *data_in,
David Woodhouse0bc43822008-12-10 15:34:49 +0000265 unsigned char *cpage_out, uint32_t *sourcelen,
266 uint32_t *dstlen)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 {
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);
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000275
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos]))
277 pos++;
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000278
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 end_rubin(&rs);
280
281 if (outpos > pos) {
282 /* We failed */
283 return -1;
284 }
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000285
286 /* Tell the caller how much we managed to compress,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 * and how much space it took */
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000288
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 outpos = (pushedbits(&rs.pp)+7)/8;
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000290
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 if (outpos >= pos)
292 return -1; /* We didn't actually compress */
293 *sourcelen = pos;
294 *dstlen = outpos;
295 return 0;
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000296}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297#if 0
298/* _compress returns the compressed size, -1 if bigger */
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000299int jffs2_rubinmips_compress(unsigned char *data_in, unsigned char *cpage_out,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 uint32_t *sourcelen, uint32_t *dstlen, void *model)
301{
David Woodhouse0bc43822008-12-10 15:34:49 +0000302 return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in,
303 cpage_out, sourcelen, dstlen);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304}
305#endif
Adrian Bunk75c96f82005-05-05 16:16:09 -0700306static int jffs2_dynrubin_compress(unsigned char *data_in,
307 unsigned char *cpage_out,
308 uint32_t *sourcelen, uint32_t *dstlen,
309 void *model)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310{
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);
David Woodhouse0bc43822008-12-10 15:34:49 +0000324 for (i=0; i<mysrclen; i++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325 histo[data_in[i]]++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326 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
David Woodhouse0bc43822008-12-10 15:34:49 +0000353 ret = rubin_do_compress(256, bits, data_in, cpage_out+8, &mysrclen,
354 &mydstlen);
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000355 if (ret)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 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
David Woodhouse0bc43822008-12-10 15:34:49 +0000371static 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)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375{
376 int outpos = 0;
377 struct rubin_state rs;
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000378
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 init_pushpull(&rs.pp, cdata_in, srclen, 0, 0);
380 init_decode(&rs, bit_divider, bits);
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000381
David Woodhouse0bc43822008-12-10 15:34:49 +0000382 while (outpos < destlen)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383 page_out[outpos++] = in_byte(&rs);
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000384}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385
386
Adrian Bunk75c96f82005-05-05 16:16:09 -0700387static int jffs2_rubinmips_decompress(unsigned char *data_in,
388 unsigned char *cpage_out,
389 uint32_t sourcelen, uint32_t dstlen,
390 void *model)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391{
David Woodhouse0bc43822008-12-10 15:34:49 +0000392 rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in,
393 cpage_out, sourcelen, dstlen);
David Woodhouseef53cb02007-07-10 10:01:22 +0100394 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395}
396
Adrian Bunk75c96f82005-05-05 16:16:09 -0700397static int jffs2_dynrubin_decompress(unsigned char *data_in,
398 unsigned char *cpage_out,
399 uint32_t sourcelen, uint32_t dstlen,
400 void *model)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401{
402 int bits[8];
403 int c;
404
405 for (c=0; c<8; c++)
406 bits[c] = data_in[c];
407
David Woodhouse0bc43822008-12-10 15:34:49 +0000408 rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8,
409 dstlen);
David Woodhouseef53cb02007-07-10 10:01:22 +0100410 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411}
412
413static struct jffs2_compressor jffs2_rubinmips_comp = {
David Woodhouse0bc43822008-12-10 15:34:49 +0000414 .priority = JFFS2_RUBINMIPS_PRIORITY,
415 .name = "rubinmips",
416 .compr = JFFS2_COMPR_DYNRUBIN,
417 .compress = NULL, /*&jffs2_rubinmips_compress,*/
418 .decompress = &jffs2_rubinmips_decompress,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419#ifdef JFFS2_RUBINMIPS_DISABLED
David Woodhouse0bc43822008-12-10 15:34:49 +0000420 .disabled = 1,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421#else
David Woodhouse0bc43822008-12-10 15:34:49 +0000422 .disabled = 0,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423#endif
424};
425
426int jffs2_rubinmips_init(void)
427{
David Woodhouse0bc43822008-12-10 15:34:49 +0000428 return jffs2_register_compressor(&jffs2_rubinmips_comp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429}
430
431void jffs2_rubinmips_exit(void)
432{
David Woodhouse0bc43822008-12-10 15:34:49 +0000433 jffs2_unregister_compressor(&jffs2_rubinmips_comp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434}
435
436static struct jffs2_compressor jffs2_dynrubin_comp = {
David Woodhouse0bc43822008-12-10 15:34:49 +0000437 .priority = JFFS2_DYNRUBIN_PRIORITY,
438 .name = "dynrubin",
439 .compr = JFFS2_COMPR_RUBINMIPS,
440 .compress = jffs2_dynrubin_compress,
441 .decompress = &jffs2_dynrubin_decompress,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442#ifdef JFFS2_DYNRUBIN_DISABLED
David Woodhouse0bc43822008-12-10 15:34:49 +0000443 .disabled = 1,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444#else
David Woodhouse0bc43822008-12-10 15:34:49 +0000445 .disabled = 0,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700446#endif
447};
448
449int jffs2_dynrubin_init(void)
450{
David Woodhouse0bc43822008-12-10 15:34:49 +0000451 return jffs2_register_compressor(&jffs2_dynrubin_comp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452}
453
454void jffs2_dynrubin_exit(void)
455{
David Woodhouse0bc43822008-12-10 15:34:49 +0000456 jffs2_unregister_compressor(&jffs2_dynrubin_comp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457}