1/* 2 * JFFS2 -- Journalling Flash File System, Version 2. 3 * 4 * Copyright �� 2001-2007 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 */ 11 12#include <linux/string.h> 13#include <linux/types.h> 14#include <linux/jffs2.h> 15#include <linux/errno.h> 16#include "compr.h" 17 18 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 24#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 36struct 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}; 45 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 92static void init_rubin(struct rubin_state *rs, int div, int *bits) 93{ 94 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++; 113 114 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) 141{ 142 143 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{ 155 init_rubin(rs, div, bits); 156 157 /* 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 261static int rubin_do_compress(int bit_divider, int *bits, unsigned char *data_in, 262 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); 271 272 while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos])) 273 pos++; 274 275 end_rubin(&rs); 276 277 if (outpos > pos) { 278 /* We failed */ 279 return -1; 280 } 281 282 /* Tell the caller how much we managed to compress, 283 * and how much space it took */ 284 285 outpos = (pushedbits(&rs.pp)+7)/8; 286 287 if (outpos >= pos) 288 return -1; /* We didn't actually compress */ 289 *sourcelen = pos; 290 *dstlen = outpos; 291 return 0; 292} 293static int jffs2_dynrubin_compress(unsigned char *data_in, 294 unsigned char *cpage_out, 295 uint32_t *sourcelen, uint32_t *dstlen, 296 void *model) 297{ 298 int bits[8]; 299 unsigned char histo[256]; 300 int i; 301 int ret; 302 uint32_t mysrclen, mydstlen; 303 304 mysrclen = *sourcelen; 305 mydstlen = *dstlen - 8; 306 307 if (*dstlen <= 12) 308 return -1; 309 310 memset(histo, 0, 256); 311 for (i=0; i<mysrclen; i++) { 312 histo[data_in[i]]++; 313 } 314 memset(bits, 0, sizeof(int)*8); 315 for (i=0; i<256; i++) { 316 if (i&128) 317 bits[7] += histo[i]; 318 if (i&64) 319 bits[6] += histo[i]; 320 if (i&32) 321 bits[5] += histo[i]; 322 if (i&16) 323 bits[4] += histo[i]; 324 if (i&8) 325 bits[3] += histo[i]; 326 if (i&4) 327 bits[2] += histo[i]; 328 if (i&2) 329 bits[1] += histo[i]; 330 if (i&1) 331 bits[0] += histo[i]; 332 } 333 334 for (i=0; i<8; i++) { 335 bits[i] = (bits[i] * 256) / mysrclen; 336 if (!bits[i]) bits[i] = 1; 337 if (bits[i] > 255) bits[i] = 255; 338 cpage_out[i] = bits[i]; 339 } 340 341 ret = rubin_do_compress(256, bits, data_in, cpage_out+8, &mysrclen, &mydstlen); 342 if (ret) 343 return ret; 344 345 /* Add back the 8 bytes we took for the probabilities */ 346 mydstlen += 8; 347 348 if (mysrclen <= mydstlen) { 349 /* We compressed */ 350 return -1; 351 } 352 353 *sourcelen = mysrclen; 354 *dstlen = mydstlen; 355 return 0; 356} 357 358static void rubin_do_decompress(int bit_divider, int *bits, unsigned char *cdata_in, 359 unsigned char *page_out, uint32_t srclen, uint32_t destlen) 360{ 361 int outpos = 0; 362 struct rubin_state rs; 363 364 init_pushpull(&rs.pp, cdata_in, srclen, 0, 0); 365 init_decode(&rs, bit_divider, bits); 366 367 while (outpos < destlen) { 368 page_out[outpos++] = in_byte(&rs); 369 } 370} 371 372 373static int jffs2_rubinmips_decompress(unsigned char *data_in, 374 unsigned char *cpage_out, 375 uint32_t sourcelen, uint32_t dstlen, 376 void *model) 377{ 378 rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen); 379 return 0; 380} 381 382static int jffs2_dynrubin_decompress(unsigned char *data_in, 383 unsigned char *cpage_out, 384 uint32_t sourcelen, uint32_t dstlen, 385 void *model) 386{ 387 int bits[8]; 388 int c; 389 390 for (c=0; c<8; c++) 391 bits[c] = data_in[c]; 392 393 rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8, dstlen); 394 return 0; 395} 396 397static struct jffs2_compressor jffs2_rubinmips_comp = { 398 .priority = JFFS2_RUBINMIPS_PRIORITY, 399 .name = "rubinmips", 400 .compr = JFFS2_COMPR_DYNRUBIN, 401 .compress = NULL, /*&jffs2_rubinmips_compress,*/ 402 .decompress = &jffs2_rubinmips_decompress, 403#ifdef JFFS2_RUBINMIPS_DISABLED 404 .disabled = 1, 405#else 406 .disabled = 0, 407#endif 408}; 409 410int jffs2_rubinmips_init(void) 411{ 412 return jffs2_register_compressor(&jffs2_rubinmips_comp); 413} 414 415void jffs2_rubinmips_exit(void) 416{ 417 jffs2_unregister_compressor(&jffs2_rubinmips_comp); 418} 419 420static struct jffs2_compressor jffs2_dynrubin_comp = { 421 .priority = JFFS2_DYNRUBIN_PRIORITY, 422 .name = "dynrubin", 423 .compr = JFFS2_COMPR_RUBINMIPS, 424 .compress = jffs2_dynrubin_compress, 425 .decompress = &jffs2_dynrubin_decompress, 426#ifdef JFFS2_DYNRUBIN_DISABLED 427 .disabled = 1, 428#else 429 .disabled = 0, 430#endif 431}; 432 433int jffs2_dynrubin_init(void) 434{ 435 return jffs2_register_compressor(&jffs2_dynrubin_comp); 436} 437 438void jffs2_dynrubin_exit(void) 439{ 440 jffs2_unregister_compressor(&jffs2_dynrubin_comp); 441} 442