source: rtems/cpukit/libfs/src/jffs2/src/compr_rubin.c @ 0c0f128

4.115
Last change on this file since 0c0f128 was 0c0f128, checked in by Sebastian Huber <sebastian.huber@…>, on 09/12/13 at 13:57:47

JFFS2: Import from Linux

Import of Journalling Flash File System, Version 2 from Linux 3.11.
This part of the Linux kernel is under a separate license which is
similar to the RTEMS license.

The file "cpukit/libfs/src/jffs2/include/linux/jffs2.h" is a copy of
"linux-3.11/include/uapi/linux/jffs2.h".

The file "LICENSE.JFFS2" is a copy of "linux-3.11/fs/jffs2/LICENCE".

The files

"linux-3.11/fs/jffs2/LICENCE",
"linux-3.11/fs/jffs2/acl.h",
"linux-3.11/fs/jffs2/build.c",
"linux-3.11/fs/jffs2/compr.c",
"linux-3.11/fs/jffs2/compr.h",
"linux-3.11/fs/jffs2/compr_rtime.c",
"linux-3.11/fs/jffs2/compr_rubin.c",
"linux-3.11/fs/jffs2/compr_zlib.c",
"linux-3.11/fs/jffs2/debug.c",
"linux-3.11/fs/jffs2/debug.h",
"linux-3.11/fs/jffs2/erase.c",
"linux-3.11/fs/jffs2/gc.c",
"linux-3.11/fs/jffs2/jffs2_fs_i.h",
"linux-3.11/fs/jffs2/jffs2_fs_sb.h",
"linux-3.11/fs/jffs2/nodelist.c",
"linux-3.11/fs/jffs2/nodelist.h",
"linux-3.11/fs/jffs2/nodemgmt.c",
"linux-3.11/fs/jffs2/read.c",
"linux-3.11/fs/jffs2/readinode.c",
"linux-3.11/fs/jffs2/scan.c",
"linux-3.11/fs/jffs2/summary.h",
"linux-3.11/fs/jffs2/write.c", and
"linux-3.11/fs/jffs2/xattr.h"

are copied to "cpukit/libfs/src/jffs2/src".

  • Property mode set to 100644
File size: 8.8 KB
Line 
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
28static int bits_mips[8] = { 277, 249, 290, 267, 229, 341, 212, 241};
29
30struct pushpull {
31        unsigned char *buf;
32        unsigned int buflen;
33        unsigned int ofs;
34        unsigned int reserve;
35};
36
37struct 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
47static 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
57static 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
72static inline int pushedbits(struct pushpull *pp)
73{
74        return pp->ofs;
75}
76
77static 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
87static inline int pulledbits(struct pushpull *pp)
88{
89        return pp->ofs;
90}
91
92
93static void init_rubin(struct rubin_state *rs, int div, int *bits)
94{
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
102        for (c=0; c<8; c++)
103                rs->bits[c] = bits[c];
104}
105
106
107static int encode(struct rubin_state *rs, long A, long B, int symbol)
108{
109
110        long i0, i1;
111        int ret;
112
113        while ((rs->q >= UPPER_BIT_RUBIN) ||
114               ((rs->p + rs->q) <= UPPER_BIT_RUBIN)) {
115                rs->bit_number++;
116
117                ret = pushbit(&rs->pp, (rs->q & UPPER_BIT_RUBIN) ? 1 : 0, 0);
118                if (ret)
119                        return ret;
120                rs->q &= LOWER_BITS_RUBIN;
121                rs->q <<= 1;
122                rs->p <<= 1;
123        }
124        i0 = A * rs->p / (A + B);
125        if (i0 <= 0)
126                i0 = 1;
127
128        if (i0 >= rs->p)
129                i0 = rs->p - 1;
130
131        i1 = rs->p - i0;
132
133        if (symbol == 0)
134                rs->p = i0;
135        else {
136                rs->p = i1;
137                rs->q += i0;
138        }
139        return 0;
140}
141
142
143static void end_rubin(struct rubin_state *rs)
144{
145
146        int i;
147
148        for (i = 0; i < RUBIN_REG_SIZE; i++) {
149                pushbit(&rs->pp, (UPPER_BIT_RUBIN & rs->q) ? 1 : 0, 1);
150                rs->q &= LOWER_BITS_RUBIN;
151                rs->q <<= 1;
152        }
153}
154
155
156static void init_decode(struct rubin_state *rs, int div, int *bits)
157{
158        init_rubin(rs, div, bits);
159
160        /* behalve lower */
161        rs->rec_q = 0;
162
163        for (rs->bit_number = 0; rs->bit_number++ < RUBIN_REG_SIZE;
164             rs->rec_q = rs->rec_q * 2 + (long) (pullbit(&rs->pp)))
165                ;
166}
167
168static void __do_decode(struct rubin_state *rs, unsigned long p,
169                        unsigned long q)
170{
171        register unsigned long lower_bits_rubin = LOWER_BITS_RUBIN;
172        unsigned long rec_q;
173        int c, bits = 0;
174
175        /*
176         * First, work out how many bits we need from the input stream.
177         * Note that we have already done the initial check on this
178         * loop prior to calling this function.
179         */
180        do {
181                bits++;
182                q &= lower_bits_rubin;
183                q <<= 1;
184                p <<= 1;
185        } while ((q >= UPPER_BIT_RUBIN) || ((p + q) <= UPPER_BIT_RUBIN));
186
187        rs->p = p;
188        rs->q = q;
189
190        rs->bit_number += bits;
191
192        /*
193         * Now get the bits.  We really want this to be "get n bits".
194         */
195        rec_q = rs->rec_q;
196        do {
197                c = pullbit(&rs->pp);
198                rec_q &= lower_bits_rubin;
199                rec_q <<= 1;
200                rec_q += c;
201        } while (--bits);
202        rs->rec_q = rec_q;
203}
204
205static int decode(struct rubin_state *rs, long A, long B)
206{
207        unsigned long p = rs->p, q = rs->q;
208        long i0, threshold;
209        int symbol;
210
211        if (q >= UPPER_BIT_RUBIN || ((p + q) <= UPPER_BIT_RUBIN))
212                __do_decode(rs, p, q);
213
214        i0 = A * rs->p / (A + B);
215        if (i0 <= 0)
216                i0 = 1;
217
218        if (i0 >= rs->p)
219                i0 = rs->p - 1;
220
221        threshold = rs->q + i0;
222        symbol = rs->rec_q >= threshold;
223        if (rs->rec_q >= threshold) {
224                rs->q += i0;
225                i0 = rs->p - i0;
226        }
227
228        rs->p = i0;
229
230        return symbol;
231}
232
233
234
235static int out_byte(struct rubin_state *rs, unsigned char byte)
236{
237        int i, ret;
238        struct rubin_state rs_copy;
239        rs_copy = *rs;
240
241        for (i=0; i<8; i++) {
242                ret = encode(rs, rs->bit_divider-rs->bits[i],
243                             rs->bits[i], byte & 1);
244                if (ret) {
245                        /* Failed. Restore old state */
246                        *rs = rs_copy;
247                        return ret;
248                }
249                byte >>= 1 ;
250        }
251        return 0;
252}
253
254static int in_byte(struct rubin_state *rs)
255{
256        int i, result = 0, bit_divider = rs->bit_divider;
257
258        for (i = 0; i < 8; i++)
259                result |= decode(rs, bit_divider - rs->bits[i],
260                                 rs->bits[i]) << i;
261
262        return result;
263}
264
265
266
267static int rubin_do_compress(int bit_divider, int *bits, unsigned char *data_in,
268                             unsigned char *cpage_out, uint32_t *sourcelen,
269                             uint32_t *dstlen)
270        {
271        int outpos = 0;
272        int pos=0;
273        struct rubin_state rs;
274
275        init_pushpull(&rs.pp, cpage_out, *dstlen * 8, 0, 32);
276
277        init_rubin(&rs, bit_divider, bits);
278
279        while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos]))
280                pos++;
281
282        end_rubin(&rs);
283
284        if (outpos > pos) {
285                /* We failed */
286                return -1;
287        }
288
289        /* Tell the caller how much we managed to compress,
290         * and how much space it took */
291
292        outpos = (pushedbits(&rs.pp)+7)/8;
293
294        if (outpos >= pos)
295                return -1; /* We didn't actually compress */
296        *sourcelen = pos;
297        *dstlen = outpos;
298        return 0;
299}
300#if 0
301/* _compress returns the compressed size, -1 if bigger */
302int jffs2_rubinmips_compress(unsigned char *data_in, unsigned char *cpage_out,
303                   uint32_t *sourcelen, uint32_t *dstlen)
304{
305        return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in,
306                                 cpage_out, sourcelen, dstlen);
307}
308#endif
309static int jffs2_dynrubin_compress(unsigned char *data_in,
310                                   unsigned char *cpage_out,
311                                   uint32_t *sourcelen, uint32_t *dstlen)
312{
313        int bits[8];
314        unsigned char histo[256];
315        int i;
316        int ret;
317        uint32_t mysrclen, mydstlen;
318
319        mysrclen = *sourcelen;
320        mydstlen = *dstlen - 8;
321
322        if (*dstlen <= 12)
323                return -1;
324
325        memset(histo, 0, 256);
326        for (i=0; i<mysrclen; i++)
327                histo[data_in[i]]++;
328        memset(bits, 0, sizeof(int)*8);
329        for (i=0; i<256; i++) {
330                if (i&128)
331                        bits[7] += histo[i];
332                if (i&64)
333                        bits[6] += histo[i];
334                if (i&32)
335                        bits[5] += histo[i];
336                if (i&16)
337                        bits[4] += histo[i];
338                if (i&8)
339                        bits[3] += histo[i];
340                if (i&4)
341                        bits[2] += histo[i];
342                if (i&2)
343                        bits[1] += histo[i];
344                if (i&1)
345                        bits[0] += histo[i];
346        }
347
348        for (i=0; i<8; i++) {
349                bits[i] = (bits[i] * 256) / mysrclen;
350                if (!bits[i]) bits[i] = 1;
351                if (bits[i] > 255) bits[i] = 255;
352                cpage_out[i] = bits[i];
353        }
354
355        ret = rubin_do_compress(256, bits, data_in, cpage_out+8, &mysrclen,
356                                &mydstlen);
357        if (ret)
358                return ret;
359
360        /* Add back the 8 bytes we took for the probabilities */
361        mydstlen += 8;
362
363        if (mysrclen <= mydstlen) {
364                /* We compressed */
365                return -1;
366        }
367
368        *sourcelen = mysrclen;
369        *dstlen = mydstlen;
370        return 0;
371}
372
373static void rubin_do_decompress(int bit_divider, int *bits,
374                                unsigned char *cdata_in,
375                                unsigned char *page_out, uint32_t srclen,
376                                uint32_t destlen)
377{
378        int outpos = 0;
379        struct rubin_state rs;
380
381        init_pushpull(&rs.pp, cdata_in, srclen, 0, 0);
382        init_decode(&rs, bit_divider, bits);
383
384        while (outpos < destlen)
385                page_out[outpos++] = in_byte(&rs);
386}
387
388
389static int jffs2_rubinmips_decompress(unsigned char *data_in,
390                                      unsigned char *cpage_out,
391                                      uint32_t sourcelen, uint32_t dstlen)
392{
393        rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in,
394                            cpage_out, sourcelen, dstlen);
395        return 0;
396}
397
398static int jffs2_dynrubin_decompress(unsigned char *data_in,
399                                     unsigned char *cpage_out,
400                                     uint32_t sourcelen, uint32_t dstlen)
401{
402        int bits[8];
403        int c;
404
405        for (c=0; c<8; c++)
406                bits[c] = data_in[c];
407
408        rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8,
409                            dstlen);
410        return 0;
411}
412
413static struct jffs2_compressor jffs2_rubinmips_comp = {
414        .priority = JFFS2_RUBINMIPS_PRIORITY,
415        .name = "rubinmips",
416        .compr = JFFS2_COMPR_DYNRUBIN,
417        .compress = NULL, /*&jffs2_rubinmips_compress,*/
418        .decompress = &jffs2_rubinmips_decompress,
419#ifdef JFFS2_RUBINMIPS_DISABLED
420        .disabled = 1,
421#else
422        .disabled = 0,
423#endif
424};
425
426int jffs2_rubinmips_init(void)
427{
428        return jffs2_register_compressor(&jffs2_rubinmips_comp);
429}
430
431void jffs2_rubinmips_exit(void)
432{
433        jffs2_unregister_compressor(&jffs2_rubinmips_comp);
434}
435
436static struct jffs2_compressor jffs2_dynrubin_comp = {
437        .priority = JFFS2_DYNRUBIN_PRIORITY,
438        .name = "dynrubin",
439        .compr = JFFS2_COMPR_RUBINMIPS,
440        .compress = jffs2_dynrubin_compress,
441        .decompress = &jffs2_dynrubin_decompress,
442#ifdef JFFS2_DYNRUBIN_DISABLED
443        .disabled = 1,
444#else
445        .disabled = 0,
446#endif
447};
448
449int jffs2_dynrubin_init(void)
450{
451        return jffs2_register_compressor(&jffs2_dynrubin_comp);
452}
453
454void jffs2_dynrubin_exit(void)
455{
456        jffs2_unregister_compressor(&jffs2_dynrubin_comp);
457}
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