1/*
2 * JFFS2 -- Journalling Flash File System, Version 2.
3 *
4 * Copyright (C) 2001 Red Hat, Inc.
5 *
6 * Created by Arjan van de Ven <arjanv@redhat.com>
7 *
8 * Heavily modified by Russ Dill <Russ.Dill@asu.edu> in an attempt at
9 * a little more speed.
10 *
11 * The original JFFS, from which the design for JFFS2 was derived,
12 * was designed and implemented by Axis Communications AB.
13 *
14 * The contents of this file are subject to the Red Hat eCos Public
15 * License Version 1.1 (the "Licence"); you may not use this file
16 * except in compliance with the Licence.  You may obtain a copy of
17 * the Licence at http://www.redhat.com/
18 *
19 * Software distributed under the Licence is distributed on an "AS IS"
20 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.
21 * See the Licence for the specific language governing rights and
22 * limitations under the Licence.
23 *
24 * The Original Code is JFFS2 - Journalling Flash File System, version 2
25 *
26 * Alternatively, the contents of this file may be used under the
27 * terms of the GNU General Public License version 2 (the "GPL"), in
28 * which case the provisions of the GPL are applicable instead of the
29 * above.  If you wish to allow the use of your version of this file
30 * only under the terms of the GPL and not to allow others to use your
31 * version of this file under the RHEPL, indicate your decision by
32 * deleting the provisions above and replace them with the notice and
33 * other provisions required by the GPL.  If you do not delete the
34 * provisions above, a recipient may use your version of this file
35 * under either the RHEPL or the GPL.
36 *
37 * $Id: compr_rubin.c,v 1.2 2002/01/24 22:58:42 rfeany Exp $
38 *
39 */
40
41#include <config.h>
42#include <jffs2/jffs2.h>
43#include <jffs2/compr_rubin.h>
44
45
46void rubin_do_decompress(unsigned char *bits, unsigned char *in,
47			 unsigned char *page_out, __u32 destlen)
48{
49	register char *curr = (char *)page_out;
50	char *end = (char *)(page_out + destlen);
51	register unsigned long temp;
52	register unsigned long result;
53	register unsigned long p;
54	register unsigned long q;
55	register unsigned long rec_q;
56	register unsigned long bit;
57	register long i0;
58	unsigned long i;
59
60	/* init_pushpull */
61	temp = *(u32 *) in;
62	bit = 16;
63
64	/* init_rubin */
65	q = 0;
66	p = (long) (2 * UPPER_BIT_RUBIN);
67
68	/* init_decode */
69	rec_q = (in[0] << 8) | in[1];
70
71	while (curr < end) {
72		/* in byte */
73
74		result = 0;
75		for (i = 0; i < 8; i++) {
76			/* decode */
77
78			while ((q & UPPER_BIT_RUBIN) || ((p + q) <= UPPER_BIT_RUBIN)) {
79				q &= ~UPPER_BIT_RUBIN;
80				q <<= 1;
81				p <<= 1;
82				rec_q &= ~UPPER_BIT_RUBIN;
83				rec_q <<= 1;
84				rec_q |= (temp >> (bit++ ^ 7)) & 1;
85				if (bit > 31) {
86					u32 *p = (u32 *)in;
87					bit = 0;
88					temp = *(++p);
89					in = (unsigned char *)p;
90				}
91			}
92			i0 =  (bits[i] * p) >> 8;
93
94			if (i0 <= 0) i0 = 1;
95			/* if it fails, it fails, we have our crc
96			if (i0 >= p) i0 = p - 1; */
97
98			result >>= 1;
99			if (rec_q < q + i0) {
100				/* result |= 0x00; */
101				p = i0;
102			} else {
103				result |= 0x80;
104				p -= i0;
105				q += i0;
106			}
107		}
108		*(curr++) = result;
109	}
110}
111
112void dynrubin_decompress(unsigned char *data_in, unsigned char *cpage_out,
113		   unsigned long sourcelen, unsigned long dstlen)
114{
115	unsigned char bits[8];
116	int c;
117
118	for (c=0; c<8; c++)
119		bits[c] = (256 - data_in[c]);
120
121	rubin_do_decompress(bits, data_in+8, cpage_out, dstlen);
122}
123