2 * JFFS2 -- Journalling Flash File System, Version 2.
4 * Copyright (C) 2001, 2002 Red Hat, Inc.
6 * Created by Arjan van de Ven <arjanv@redhat.com>
8 * For licensing information, see the file 'LICENCE' in this directory.
10 * $Id: compr_rubin.c,v 1.20 2004/06/23 16:34:40 havasi Exp $
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"
22 static void init_rubin(struct rubin_state *rs, int div, int *bits)
27 rs->p = (long) (2 * UPPER_BIT_RUBIN);
28 rs->bit_number = (long) 0;
29 rs->bit_divider = div;
31 rs->bits[c] = bits[c];
35 static int encode(struct rubin_state *rs, long A, long B, int symbol)
41 while ((rs->q >= UPPER_BIT_RUBIN) || ((rs->p + rs->q) <= UPPER_BIT_RUBIN)) {
44 ret = pushbit(&rs->pp, (rs->q & UPPER_BIT_RUBIN) ? 1 : 0, 0);
47 rs->q &= LOWER_BITS_RUBIN;
51 i0 = A * rs->p / (A + B);
70 static void end_rubin(struct rubin_state *rs)
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;
83 static void init_decode(struct rubin_state *rs, int div, int *bits)
85 init_rubin(rs, div, bits);
90 for (rs->bit_number = 0; rs->bit_number++ < RUBIN_REG_SIZE; rs->rec_q = rs->rec_q * 2 + (long) (pullbit(&rs->pp)))
94 static void __do_decode(struct rubin_state *rs, unsigned long p, unsigned long q)
96 register unsigned long lower_bits_rubin = LOWER_BITS_RUBIN;
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.
107 q &= lower_bits_rubin;
110 } while ((q >= UPPER_BIT_RUBIN) || ((p + q) <= UPPER_BIT_RUBIN));
115 rs->bit_number += bits;
118 * Now get the bits. We really want this to be "get n bits".
122 c = pullbit(&rs->pp);
123 rec_q &= lower_bits_rubin;
130 static int decode(struct rubin_state *rs, long A, long B)
132 unsigned long p = rs->p, q = rs->q;
136 if (q >= UPPER_BIT_RUBIN || ((p + q) <= UPPER_BIT_RUBIN))
137 __do_decode(rs, p, q);
139 i0 = A * rs->p / (A + B);
147 threshold = rs->q + i0;
148 symbol = rs->rec_q >= threshold;
149 if (rs->rec_q >= threshold) {
161 static int out_byte(struct rubin_state *rs, unsigned char byte)
164 struct rubin_state rs_copy;
168 ret = encode(rs, rs->bit_divider-rs->bits[i],rs->bits[i],byte&1);
170 /* Failed. Restore old state */
179 static int in_byte(struct rubin_state *rs)
181 int i, result = 0, bit_divider = rs->bit_divider;
183 for (i = 0; i < 8; i++)
184 result |= decode(rs, bit_divider - rs->bits[i], rs->bits[i]) << i;
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)
196 struct rubin_state rs;
198 init_pushpull(&rs.pp, cpage_out, *dstlen * 8, 0, 32);
200 init_rubin(&rs, bit_divider, bits);
202 while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos]))
212 /* Tell the caller how much we managed to compress,
213 * and how much space it took */
215 outpos = (pushedbits(&rs.pp)+7)/8;
218 return -1; /* We didn't actually compress */
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)
228 return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen);
231 int jffs2_dynrubin_compress(unsigned char *data_in, unsigned char *cpage_out,
232 uint32_t *sourcelen, uint32_t *dstlen, void *model)
235 unsigned char histo[256];
238 uint32_t mysrclen, mydstlen;
240 mysrclen = *sourcelen;
241 mydstlen = *dstlen - 8;
246 memset(histo, 0, 256);
247 for (i=0; i<mysrclen; i++) {
250 memset(bits, 0, sizeof(int)*8);
251 for (i=0; i<256; i++) {
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];
277 ret = rubin_do_compress(256, bits, data_in, cpage_out+8, &mysrclen, &mydstlen);
281 /* Add back the 8 bytes we took for the probabilities */
284 if (mysrclen <= mydstlen) {
289 *sourcelen = mysrclen;
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)
298 struct rubin_state rs;
300 init_pushpull(&rs.pp, cdata_in, srclen, 0, 0);
301 init_decode(&rs, bit_divider, bits);
303 while (outpos < destlen) {
304 page_out[outpos++] = in_byte(&rs);
309 int jffs2_rubinmips_decompress(unsigned char *data_in, unsigned char *cpage_out,
310 uint32_t sourcelen, uint32_t dstlen, void *model)
312 rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen);
316 int jffs2_dynrubin_decompress(unsigned char *data_in, unsigned char *cpage_out,
317 uint32_t sourcelen, uint32_t dstlen, void *model)
323 bits[c] = data_in[c];
325 rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8, dstlen);
329 static struct jffs2_compressor jffs2_rubinmips_comp = {
330 .priority = JFFS2_RUBINMIPS_PRIORITY,
332 .compr = JFFS2_COMPR_DYNRUBIN,
333 .compress = NULL, /*&jffs2_rubinmips_compress,*/
334 .decompress = &jffs2_rubinmips_decompress,
335 #ifdef JFFS2_RUBINMIPS_DISABLED
342 int jffs2_rubinmips_init(void)
344 return jffs2_register_compressor(&jffs2_rubinmips_comp);
347 void jffs2_rubinmips_exit(void)
349 jffs2_unregister_compressor(&jffs2_rubinmips_comp);
352 static struct jffs2_compressor jffs2_dynrubin_comp = {
353 .priority = JFFS2_DYNRUBIN_PRIORITY,
355 .compr = JFFS2_COMPR_RUBINMIPS,
356 .compress = jffs2_dynrubin_compress,
357 .decompress = &jffs2_dynrubin_decompress,
358 #ifdef JFFS2_DYNRUBIN_DISABLED
365 int jffs2_dynrubin_init(void)
367 return jffs2_register_compressor(&jffs2_dynrubin_comp);
370 void jffs2_dynrubin_exit(void)
372 jffs2_unregister_compressor(&jffs2_dynrubin_comp);