[PATCH] USB Serial: move old changelog comments out of source code
[linux-2.6] / fs / jffs2 / compr_rubin.c
1 /*
2  * JFFS2 -- Journalling Flash File System, Version 2.
3  *
4  * Copyright (C) 2001, 2002 Red Hat, Inc.
5  *
6  * Created by Arjan van de Ven <arjanv@redhat.com>
7  *
8  * For licensing information, see the file 'LICENCE' in this directory.
9  *
10  * $Id: compr_rubin.c,v 1.20 2004/06/23 16:34:40 havasi Exp $
11  *
12  */
13
14  
15 #include <linux/string.h>
16 #include <linux/types.h>
17 #include <linux/jffs2.h>
18 #include "compr_rubin.h"
19 #include "histo_mips.h"
20 #include "compr.h"
21
22 static void init_rubin(struct rubin_state *rs, int div, int *bits)
23 {       
24         int c;
25
26         rs->q = 0;
27         rs->p = (long) (2 * UPPER_BIT_RUBIN);
28         rs->bit_number = (long) 0;
29         rs->bit_divider = div;
30         for (c=0; c<8; c++)
31                 rs->bits[c] = bits[c];
32 }
33
34
35 static int encode(struct rubin_state *rs, long A, long B, int symbol)
36 {
37
38         long i0, i1;
39         int ret;
40
41         while ((rs->q >= UPPER_BIT_RUBIN) || ((rs->p + rs->q) <= UPPER_BIT_RUBIN)) {
42                 rs->bit_number++;
43                 
44                 ret = pushbit(&rs->pp, (rs->q & UPPER_BIT_RUBIN) ? 1 : 0, 0);
45                 if (ret)
46                         return ret;
47                 rs->q &= LOWER_BITS_RUBIN;
48                 rs->q <<= 1;
49                 rs->p <<= 1;
50         }
51         i0 = A * rs->p / (A + B);
52         if (i0 <= 0) {
53                 i0 = 1;
54         }
55         if (i0 >= rs->p) {
56                 i0 = rs->p - 1;
57         }
58         i1 = rs->p - i0;
59
60         if (symbol == 0)
61                 rs->p = i0;
62         else {
63                 rs->p = i1;
64                 rs->q += i0;
65         }
66         return 0;
67 }
68
69
70 static void end_rubin(struct rubin_state *rs)
71 {                               
72
73         int i;
74
75         for (i = 0; i < RUBIN_REG_SIZE; i++) {
76                 pushbit(&rs->pp, (UPPER_BIT_RUBIN & rs->q) ? 1 : 0, 1);
77                 rs->q &= LOWER_BITS_RUBIN;
78                 rs->q <<= 1;
79         }
80 }
81
82
83 static void init_decode(struct rubin_state *rs, int div, int *bits)
84 {
85         init_rubin(rs, div, bits);              
86
87         /* behalve lower */
88         rs->rec_q = 0;
89
90         for (rs->bit_number = 0; rs->bit_number++ < RUBIN_REG_SIZE; rs->rec_q = rs->rec_q * 2 + (long) (pullbit(&rs->pp)))
91                 ;
92 }
93
94 static void __do_decode(struct rubin_state *rs, unsigned long p, unsigned long q)
95 {
96         register unsigned long lower_bits_rubin = LOWER_BITS_RUBIN;
97         unsigned long rec_q;
98         int c, bits = 0;
99
100         /*
101          * First, work out how many bits we need from the input stream.
102          * Note that we have already done the initial check on this
103          * loop prior to calling this function.
104          */
105         do {
106                 bits++;
107                 q &= lower_bits_rubin;
108                 q <<= 1;
109                 p <<= 1;
110         } while ((q >= UPPER_BIT_RUBIN) || ((p + q) <= UPPER_BIT_RUBIN));
111
112         rs->p = p;
113         rs->q = q;
114
115         rs->bit_number += bits;
116
117         /*
118          * Now get the bits.  We really want this to be "get n bits".
119          */
120         rec_q = rs->rec_q;
121         do {
122                 c = pullbit(&rs->pp);
123                 rec_q &= lower_bits_rubin;
124                 rec_q <<= 1;
125                 rec_q += c;
126         } while (--bits);
127         rs->rec_q = rec_q;
128 }
129
130 static int decode(struct rubin_state *rs, long A, long B)
131 {
132         unsigned long p = rs->p, q = rs->q;
133         long i0, threshold;
134         int symbol;
135
136         if (q >= UPPER_BIT_RUBIN || ((p + q) <= UPPER_BIT_RUBIN))
137                 __do_decode(rs, p, q);
138
139         i0 = A * rs->p / (A + B);
140         if (i0 <= 0) {
141                 i0 = 1;
142         }
143         if (i0 >= rs->p) {
144                 i0 = rs->p - 1;
145         }
146
147         threshold = rs->q + i0;
148         symbol = rs->rec_q >= threshold;
149         if (rs->rec_q >= threshold) {
150                 rs->q += i0;
151                 i0 = rs->p - i0;
152         }
153
154         rs->p = i0;
155
156         return symbol;
157 }
158
159
160
161 static int out_byte(struct rubin_state *rs, unsigned char byte)
162 {
163         int i, ret;
164         struct rubin_state rs_copy;
165         rs_copy = *rs;
166
167         for (i=0;i<8;i++) {
168                 ret = encode(rs, rs->bit_divider-rs->bits[i],rs->bits[i],byte&1);
169                 if (ret) {
170                         /* Failed. Restore old state */
171                         *rs = rs_copy;
172                         return ret;
173                 }
174                 byte=byte>>1;
175         }
176         return 0;
177 }
178
179 static int in_byte(struct rubin_state *rs)
180 {
181         int i, result = 0, bit_divider = rs->bit_divider;
182
183         for (i = 0; i < 8; i++)
184                 result |= decode(rs, bit_divider - rs->bits[i], rs->bits[i]) << i;
185
186         return result;
187 }
188
189
190
191 static int rubin_do_compress(int bit_divider, int *bits, unsigned char *data_in, 
192                       unsigned char *cpage_out, uint32_t *sourcelen, uint32_t *dstlen)
193         {
194         int outpos = 0;
195         int pos=0;
196         struct rubin_state rs;
197
198         init_pushpull(&rs.pp, cpage_out, *dstlen * 8, 0, 32);
199
200         init_rubin(&rs, bit_divider, bits);
201         
202         while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos]))
203                 pos++;
204         
205         end_rubin(&rs);
206
207         if (outpos > pos) {
208                 /* We failed */
209                 return -1;
210         }
211         
212         /* Tell the caller how much we managed to compress, 
213          * and how much space it took */
214         
215         outpos = (pushedbits(&rs.pp)+7)/8;
216         
217         if (outpos >= pos)
218                 return -1; /* We didn't actually compress */
219         *sourcelen = pos;
220         *dstlen = outpos;
221         return 0;
222 }                  
223 #if 0
224 /* _compress returns the compressed size, -1 if bigger */
225 int jffs2_rubinmips_compress(unsigned char *data_in, unsigned char *cpage_out, 
226                    uint32_t *sourcelen, uint32_t *dstlen, void *model)
227 {
228         return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen);
229 }
230 #endif
231 static int jffs2_dynrubin_compress(unsigned char *data_in,
232                                    unsigned char *cpage_out,
233                                    uint32_t *sourcelen, uint32_t *dstlen,
234                                    void *model)
235 {
236         int bits[8];
237         unsigned char histo[256];
238         int i;
239         int ret;
240         uint32_t mysrclen, mydstlen;
241
242         mysrclen = *sourcelen;
243         mydstlen = *dstlen - 8;
244
245         if (*dstlen <= 12)
246                 return -1;
247
248         memset(histo, 0, 256);
249         for (i=0; i<mysrclen; i++) {
250                 histo[data_in[i]]++;
251         }
252         memset(bits, 0, sizeof(int)*8);
253         for (i=0; i<256; i++) {
254                 if (i&128)
255                         bits[7] += histo[i];
256                 if (i&64)
257                         bits[6] += histo[i];
258                 if (i&32)
259                         bits[5] += histo[i];
260                 if (i&16)
261                         bits[4] += histo[i];
262                 if (i&8)
263                         bits[3] += histo[i];
264                 if (i&4)
265                         bits[2] += histo[i];
266                 if (i&2)
267                         bits[1] += histo[i];
268                 if (i&1)
269                         bits[0] += histo[i];
270         }
271
272         for (i=0; i<8; i++) {
273                 bits[i] = (bits[i] * 256) / mysrclen;
274                 if (!bits[i]) bits[i] = 1;
275                 if (bits[i] > 255) bits[i] = 255;
276                 cpage_out[i] = bits[i];
277         }
278
279         ret = rubin_do_compress(256, bits, data_in, cpage_out+8, &mysrclen, &mydstlen);
280         if (ret) 
281                 return ret;
282
283         /* Add back the 8 bytes we took for the probabilities */
284         mydstlen += 8;
285
286         if (mysrclen <= mydstlen) {
287                 /* We compressed */
288                 return -1;
289         }
290
291         *sourcelen = mysrclen;
292         *dstlen = mydstlen;
293         return 0;
294 }
295
296 static void rubin_do_decompress(int bit_divider, int *bits, unsigned char *cdata_in, 
297                          unsigned char *page_out, uint32_t srclen, uint32_t destlen)
298 {
299         int outpos = 0;
300         struct rubin_state rs;
301         
302         init_pushpull(&rs.pp, cdata_in, srclen, 0, 0);
303         init_decode(&rs, bit_divider, bits);
304         
305         while (outpos < destlen) {
306                 page_out[outpos++] = in_byte(&rs);
307         }
308 }                  
309
310
311 static int jffs2_rubinmips_decompress(unsigned char *data_in,
312                                       unsigned char *cpage_out,
313                                       uint32_t sourcelen, uint32_t dstlen,
314                                       void *model)
315 {
316         rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen);
317         return 0;
318 }
319
320 static int jffs2_dynrubin_decompress(unsigned char *data_in,
321                                      unsigned char *cpage_out,
322                                      uint32_t sourcelen, uint32_t dstlen,
323                                      void *model)
324 {
325         int bits[8];
326         int c;
327
328         for (c=0; c<8; c++)
329                 bits[c] = data_in[c];
330
331         rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8, dstlen);
332         return 0;
333 }
334
335 static struct jffs2_compressor jffs2_rubinmips_comp = {
336     .priority = JFFS2_RUBINMIPS_PRIORITY,
337     .name = "rubinmips",
338     .compr = JFFS2_COMPR_DYNRUBIN,
339     .compress = NULL, /*&jffs2_rubinmips_compress,*/
340     .decompress = &jffs2_rubinmips_decompress,
341 #ifdef JFFS2_RUBINMIPS_DISABLED
342     .disabled = 1,
343 #else
344     .disabled = 0,
345 #endif
346 };
347
348 int jffs2_rubinmips_init(void)
349 {
350     return jffs2_register_compressor(&jffs2_rubinmips_comp);
351 }
352
353 void jffs2_rubinmips_exit(void)
354 {
355     jffs2_unregister_compressor(&jffs2_rubinmips_comp);
356 }
357
358 static struct jffs2_compressor jffs2_dynrubin_comp = {
359     .priority = JFFS2_DYNRUBIN_PRIORITY,
360     .name = "dynrubin",
361     .compr = JFFS2_COMPR_RUBINMIPS,
362     .compress = jffs2_dynrubin_compress,
363     .decompress = &jffs2_dynrubin_decompress,
364 #ifdef JFFS2_DYNRUBIN_DISABLED
365     .disabled = 1,
366 #else
367     .disabled = 0,
368 #endif
369 };
370
371 int jffs2_dynrubin_init(void)
372 {
373     return jffs2_register_compressor(&jffs2_dynrubin_comp);
374 }
375
376 void jffs2_dynrubin_exit(void)
377 {
378     jffs2_unregister_compressor(&jffs2_dynrubin_comp);
379 }