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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
25static int bits_mips[8] = { 277,249,290,267,229,341,212,241}; /* mips32 */
26
27#include <linux/errno.h>
28
29struct pushpull {
30 unsigned char *buf;
31 unsigned int buflen;
32 unsigned int ofs;
33 unsigned int reserve;
34};
35
Andrew Mortonf6449f42007-04-26 07:27:04 +010036struct 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};
David Woodhousec00c3102007-04-25 14:16:47 +010045
46static 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
54static 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
71static inline int pushedbits(struct pushpull *pp)
72{
73 return pp->ofs;
74}
75
76static 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
86static inline int pulledbits(struct pushpull *pp)
87{
88 return pp->ofs;
89}
90
91
Linus Torvalds1da177e2005-04-16 15:20:36 -070092static void init_rubin(struct rubin_state *rs, int div, int *bits)
Thomas Gleixner182ec4e2005-11-07 11:16:07 +000093{
Linus Torvalds1da177e2005-04-16 15:20:36 -070094 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
105static 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++;
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);
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
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
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
164static 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
200static 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
231static 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
249static 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
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000261static int rubin_do_compress(int bit_divider, int *bits, unsigned char *data_in,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 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);
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000271
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272 while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos]))
273 pos++;
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000274
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 end_rubin(&rs);
276
277 if (outpos > pos) {
278 /* We failed */
279 return -1;
280 }
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000281
282 /* Tell the caller how much we managed to compress,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 * and how much space it took */
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000284
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 outpos = (pushedbits(&rs.pp)+7)/8;
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000286
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 if (outpos >= pos)
288 return -1; /* We didn't actually compress */
289 *sourcelen = pos;
290 *dstlen = outpos;
291 return 0;
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000292}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293#if 0
294/* _compress returns the compressed size, -1 if bigger */
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000295int jffs2_rubinmips_compress(unsigned char *data_in, unsigned char *cpage_out,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 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
Adrian Bunk75c96f82005-05-05 16:16:09 -0700301static int jffs2_dynrubin_compress(unsigned char *data_in,
302 unsigned char *cpage_out,
303 uint32_t *sourcelen, uint32_t *dstlen,
304 void *model)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305{
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);
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000350 if (ret)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 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
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000366static void rubin_do_decompress(int bit_divider, int *bits, unsigned char *cdata_in,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 unsigned char *page_out, uint32_t srclen, uint32_t destlen)
368{
369 int outpos = 0;
370 struct rubin_state rs;
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000371
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372 init_pushpull(&rs.pp, cdata_in, srclen, 0, 0);
373 init_decode(&rs, bit_divider, bits);
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000374
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 while (outpos < destlen) {
376 page_out[outpos++] = in_byte(&rs);
377 }
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000378}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379
380
Adrian Bunk75c96f82005-05-05 16:16:09 -0700381static int jffs2_rubinmips_decompress(unsigned char *data_in,
382 unsigned char *cpage_out,
383 uint32_t sourcelen, uint32_t dstlen,
384 void *model)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385{
386 rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen);
387 return 0;
388}
389
Adrian Bunk75c96f82005-05-05 16:16:09 -0700390static int jffs2_dynrubin_decompress(unsigned char *data_in,
391 unsigned char *cpage_out,
392 uint32_t sourcelen, uint32_t dstlen,
393 void *model)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394{
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
405static 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
418int jffs2_rubinmips_init(void)
419{
420 return jffs2_register_compressor(&jffs2_rubinmips_comp);
421}
422
423void jffs2_rubinmips_exit(void)
424{
425 jffs2_unregister_compressor(&jffs2_rubinmips_comp);
426}
427
428static 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
441int jffs2_dynrubin_init(void)
442{
443 return jffs2_register_compressor(&jffs2_dynrubin_comp);
444}
445
446void jffs2_dynrubin_exit(void)
447{
448 jffs2_unregister_compressor(&jffs2_dynrubin_comp);
449}