2 * JFFS2 -- Journalling Flash File System, Version 2.
4 * Copyright © 2001-2007 Red Hat, Inc.
6 * Created by Arjan van de Ven <arjanv@redhat.com>
8 * For licensing information, see the file 'LICENCE' in this directory.
12 #include <linux/string.h>
13 #include <linux/types.h>
14 #include <linux/jffs2.h>
15 #include <linux/errno.h>
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)
34 #define BIT_DIVIDER_MIPS 1043
35 static int bits_mips[8] = { 277,249,290,267,229,341,212,241}; /* mips32 */
37 #include <linux/errno.h>
47 static inline void init_pushpull(struct pushpull *pp, char *buf, unsigned buflen, unsigned ofs, unsigned reserve)
52 pp->reserve = reserve;
55 static inline int pushbit(struct pushpull *pp, int bit, int use_reserved)
57 if (pp->ofs >= pp->buflen - (use_reserved?0:pp->reserve)) {
62 pp->buf[pp->ofs >> 3] |= (1<<(7-(pp->ofs &7)));
65 pp->buf[pp->ofs >> 3] &= ~(1<<(7-(pp->ofs &7)));
72 static inline int pushedbits(struct pushpull *pp)
77 static inline int pullbit(struct pushpull *pp)
81 bit = (pp->buf[pp->ofs >> 3] >> (7-(pp->ofs & 7))) & 1;
87 static inline int pulledbits(struct pushpull *pp)
93 static void init_rubin(struct rubin_state *rs, int div, int *bits)
98 rs->p = (long) (2 * UPPER_BIT_RUBIN);
99 rs->bit_number = (long) 0;
100 rs->bit_divider = div;
102 rs->bits[c] = bits[c];
106 static int encode(struct rubin_state *rs, long A, long B, int symbol)
112 while ((rs->q >= UPPER_BIT_RUBIN) || ((rs->p + rs->q) <= UPPER_BIT_RUBIN)) {
115 ret = pushbit(&rs->pp, (rs->q & UPPER_BIT_RUBIN) ? 1 : 0, 0);
118 rs->q &= LOWER_BITS_RUBIN;
122 i0 = A * rs->p / (A + B);
141 static void end_rubin(struct rubin_state *rs)
146 for (i = 0; i < RUBIN_REG_SIZE; i++) {
147 pushbit(&rs->pp, (UPPER_BIT_RUBIN & rs->q) ? 1 : 0, 1);
148 rs->q &= LOWER_BITS_RUBIN;
154 static void init_decode(struct rubin_state *rs, int div, int *bits)
156 init_rubin(rs, div, bits);
161 for (rs->bit_number = 0; rs->bit_number++ < RUBIN_REG_SIZE; rs->rec_q = rs->rec_q * 2 + (long) (pullbit(&rs->pp)))
165 static void __do_decode(struct rubin_state *rs, unsigned long p, unsigned long q)
167 register unsigned long lower_bits_rubin = LOWER_BITS_RUBIN;
172 * First, work out how many bits we need from the input stream.
173 * Note that we have already done the initial check on this
174 * loop prior to calling this function.
178 q &= lower_bits_rubin;
181 } while ((q >= UPPER_BIT_RUBIN) || ((p + q) <= UPPER_BIT_RUBIN));
186 rs->bit_number += bits;
189 * Now get the bits. We really want this to be "get n bits".
193 c = pullbit(&rs->pp);
194 rec_q &= lower_bits_rubin;
201 static int decode(struct rubin_state *rs, long A, long B)
203 unsigned long p = rs->p, q = rs->q;
207 if (q >= UPPER_BIT_RUBIN || ((p + q) <= UPPER_BIT_RUBIN))
208 __do_decode(rs, p, q);
210 i0 = A * rs->p / (A + B);
218 threshold = rs->q + i0;
219 symbol = rs->rec_q >= threshold;
220 if (rs->rec_q >= threshold) {
232 static int out_byte(struct rubin_state *rs, unsigned char byte)
235 struct rubin_state rs_copy;
239 ret = encode(rs, rs->bit_divider-rs->bits[i],rs->bits[i],byte&1);
241 /* Failed. Restore old state */
250 static int in_byte(struct rubin_state *rs)
252 int i, result = 0, bit_divider = rs->bit_divider;
254 for (i = 0; i < 8; i++)
255 result |= decode(rs, bit_divider - rs->bits[i], rs->bits[i]) << i;
262 static int rubin_do_compress(int bit_divider, int *bits, unsigned char *data_in,
263 unsigned char *cpage_out, uint32_t *sourcelen, uint32_t *dstlen)
267 struct rubin_state rs;
269 init_pushpull(&rs.pp, cpage_out, *dstlen * 8, 0, 32);
271 init_rubin(&rs, bit_divider, bits);
273 while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos]))
283 /* Tell the caller how much we managed to compress,
284 * and how much space it took */
286 outpos = (pushedbits(&rs.pp)+7)/8;
289 return -1; /* We didn't actually compress */
295 /* _compress returns the compressed size, -1 if bigger */
296 int jffs2_rubinmips_compress(unsigned char *data_in, unsigned char *cpage_out,
297 uint32_t *sourcelen, uint32_t *dstlen, void *model)
299 return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen);
302 static int jffs2_dynrubin_compress(unsigned char *data_in,
303 unsigned char *cpage_out,
304 uint32_t *sourcelen, uint32_t *dstlen,
308 unsigned char histo[256];
311 uint32_t mysrclen, mydstlen;
313 mysrclen = *sourcelen;
314 mydstlen = *dstlen - 8;
319 memset(histo, 0, 256);
320 for (i=0; i<mysrclen; i++) {
323 memset(bits, 0, sizeof(int)*8);
324 for (i=0; i<256; i++) {
343 for (i=0; i<8; i++) {
344 bits[i] = (bits[i] * 256) / mysrclen;
345 if (!bits[i]) bits[i] = 1;
346 if (bits[i] > 255) bits[i] = 255;
347 cpage_out[i] = bits[i];
350 ret = rubin_do_compress(256, bits, data_in, cpage_out+8, &mysrclen, &mydstlen);
354 /* Add back the 8 bytes we took for the probabilities */
357 if (mysrclen <= mydstlen) {
362 *sourcelen = mysrclen;
367 static void rubin_do_decompress(int bit_divider, int *bits, unsigned char *cdata_in,
368 unsigned char *page_out, uint32_t srclen, uint32_t destlen)
371 struct rubin_state rs;
373 init_pushpull(&rs.pp, cdata_in, srclen, 0, 0);
374 init_decode(&rs, bit_divider, bits);
376 while (outpos < destlen) {
377 page_out[outpos++] = in_byte(&rs);
382 static int jffs2_rubinmips_decompress(unsigned char *data_in,
383 unsigned char *cpage_out,
384 uint32_t sourcelen, uint32_t dstlen,
387 rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen);
391 static int jffs2_dynrubin_decompress(unsigned char *data_in,
392 unsigned char *cpage_out,
393 uint32_t sourcelen, uint32_t dstlen,
400 bits[c] = data_in[c];
402 rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8, dstlen);
406 static struct jffs2_compressor jffs2_rubinmips_comp = {
407 .priority = JFFS2_RUBINMIPS_PRIORITY,
409 .compr = JFFS2_COMPR_DYNRUBIN,
410 .compress = NULL, /*&jffs2_rubinmips_compress,*/
411 .decompress = &jffs2_rubinmips_decompress,
412 #ifdef JFFS2_RUBINMIPS_DISABLED
419 int jffs2_rubinmips_init(void)
421 return jffs2_register_compressor(&jffs2_rubinmips_comp);
424 void jffs2_rubinmips_exit(void)
426 jffs2_unregister_compressor(&jffs2_rubinmips_comp);
429 static struct jffs2_compressor jffs2_dynrubin_comp = {
430 .priority = JFFS2_DYNRUBIN_PRIORITY,
432 .compr = JFFS2_COMPR_RUBINMIPS,
433 .compress = jffs2_dynrubin_compress,
434 .decompress = &jffs2_dynrubin_decompress,
435 #ifdef JFFS2_DYNRUBIN_DISABLED
442 int jffs2_dynrubin_init(void)
444 return jffs2_register_compressor(&jffs2_dynrubin_comp);
447 void jffs2_dynrubin_exit(void)
449 jffs2_unregister_compressor(&jffs2_dynrubin_comp);