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1da177e4 LT |
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 | int jffs2_dynrubin_compress(unsigned char *data_in, unsigned char *cpage_out, | |
232 | uint32_t *sourcelen, uint32_t *dstlen, void *model) | |
233 | { | |
234 | int bits[8]; | |
235 | unsigned char histo[256]; | |
236 | int i; | |
237 | int ret; | |
238 | uint32_t mysrclen, mydstlen; | |
239 | ||
240 | mysrclen = *sourcelen; | |
241 | mydstlen = *dstlen - 8; | |
242 | ||
243 | if (*dstlen <= 12) | |
244 | return -1; | |
245 | ||
246 | memset(histo, 0, 256); | |
247 | for (i=0; i<mysrclen; i++) { | |
248 | histo[data_in[i]]++; | |
249 | } | |
250 | memset(bits, 0, sizeof(int)*8); | |
251 | for (i=0; i<256; i++) { | |
252 | if (i&128) | |
253 | bits[7] += histo[i]; | |
254 | if (i&64) | |
255 | bits[6] += histo[i]; | |
256 | if (i&32) | |
257 | bits[5] += histo[i]; | |
258 | if (i&16) | |
259 | bits[4] += histo[i]; | |
260 | if (i&8) | |
261 | bits[3] += histo[i]; | |
262 | if (i&4) | |
263 | bits[2] += histo[i]; | |
264 | if (i&2) | |
265 | bits[1] += histo[i]; | |
266 | if (i&1) | |
267 | bits[0] += histo[i]; | |
268 | } | |
269 | ||
270 | for (i=0; i<8; i++) { | |
271 | bits[i] = (bits[i] * 256) / mysrclen; | |
272 | if (!bits[i]) bits[i] = 1; | |
273 | if (bits[i] > 255) bits[i] = 255; | |
274 | cpage_out[i] = bits[i]; | |
275 | } | |
276 | ||
277 | ret = rubin_do_compress(256, bits, data_in, cpage_out+8, &mysrclen, &mydstlen); | |
278 | if (ret) | |
279 | return ret; | |
280 | ||
281 | /* Add back the 8 bytes we took for the probabilities */ | |
282 | mydstlen += 8; | |
283 | ||
284 | if (mysrclen <= mydstlen) { | |
285 | /* We compressed */ | |
286 | return -1; | |
287 | } | |
288 | ||
289 | *sourcelen = mysrclen; | |
290 | *dstlen = mydstlen; | |
291 | return 0; | |
292 | } | |
293 | ||
294 | static void rubin_do_decompress(int bit_divider, int *bits, unsigned char *cdata_in, | |
295 | unsigned char *page_out, uint32_t srclen, uint32_t destlen) | |
296 | { | |
297 | int outpos = 0; | |
298 | struct rubin_state rs; | |
299 | ||
300 | init_pushpull(&rs.pp, cdata_in, srclen, 0, 0); | |
301 | init_decode(&rs, bit_divider, bits); | |
302 | ||
303 | while (outpos < destlen) { | |
304 | page_out[outpos++] = in_byte(&rs); | |
305 | } | |
306 | } | |
307 | ||
308 | ||
309 | int jffs2_rubinmips_decompress(unsigned char *data_in, unsigned char *cpage_out, | |
310 | uint32_t sourcelen, uint32_t dstlen, void *model) | |
311 | { | |
312 | rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen); | |
313 | return 0; | |
314 | } | |
315 | ||
316 | int jffs2_dynrubin_decompress(unsigned char *data_in, unsigned char *cpage_out, | |
317 | uint32_t sourcelen, uint32_t dstlen, void *model) | |
318 | { | |
319 | int bits[8]; | |
320 | int c; | |
321 | ||
322 | for (c=0; c<8; c++) | |
323 | bits[c] = data_in[c]; | |
324 | ||
325 | rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8, dstlen); | |
326 | return 0; | |
327 | } | |
328 | ||
329 | static struct jffs2_compressor jffs2_rubinmips_comp = { | |
330 | .priority = JFFS2_RUBINMIPS_PRIORITY, | |
331 | .name = "rubinmips", | |
332 | .compr = JFFS2_COMPR_DYNRUBIN, | |
333 | .compress = NULL, /*&jffs2_rubinmips_compress,*/ | |
334 | .decompress = &jffs2_rubinmips_decompress, | |
335 | #ifdef JFFS2_RUBINMIPS_DISABLED | |
336 | .disabled = 1, | |
337 | #else | |
338 | .disabled = 0, | |
339 | #endif | |
340 | }; | |
341 | ||
342 | int jffs2_rubinmips_init(void) | |
343 | { | |
344 | return jffs2_register_compressor(&jffs2_rubinmips_comp); | |
345 | } | |
346 | ||
347 | void jffs2_rubinmips_exit(void) | |
348 | { | |
349 | jffs2_unregister_compressor(&jffs2_rubinmips_comp); | |
350 | } | |
351 | ||
352 | static struct jffs2_compressor jffs2_dynrubin_comp = { | |
353 | .priority = JFFS2_DYNRUBIN_PRIORITY, | |
354 | .name = "dynrubin", | |
355 | .compr = JFFS2_COMPR_RUBINMIPS, | |
356 | .compress = jffs2_dynrubin_compress, | |
357 | .decompress = &jffs2_dynrubin_decompress, | |
358 | #ifdef JFFS2_DYNRUBIN_DISABLED | |
359 | .disabled = 1, | |
360 | #else | |
361 | .disabled = 0, | |
362 | #endif | |
363 | }; | |
364 | ||
365 | int jffs2_dynrubin_init(void) | |
366 | { | |
367 | return jffs2_register_compressor(&jffs2_dynrubin_comp); | |
368 | } | |
369 | ||
370 | void jffs2_dynrubin_exit(void) | |
371 | { | |
372 | jffs2_unregister_compressor(&jffs2_dynrubin_comp); | |
373 | } |