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/*
* JFFS2 -- Journalling Flash File System, Version 2.
*
* Copyright (C) 2001 Red Hat, Inc.
*
* Created by Arjan van de Ven <arjanv@redhat.com>
*
* Heavily modified by Russ Dill <Russ.Dill@asu.edu> in an attempt at
* a little more speed.
*
* The original JFFS, from which the design for JFFS2 was derived,
* was designed and implemented by Axis Communications AB.
*
* The contents of this file are subject to the Red Hat eCos Public
* License Version 1.1 (the "Licence"); you may not use this file
* except in compliance with the Licence. You may obtain a copy of
* the Licence at http://www.redhat.com/
*
* Software distributed under the Licence is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.
* See the Licence for the specific language governing rights and
* limitations under the Licence.
*
* The Original Code is JFFS2 - Journalling Flash File System, version 2
*
* Alternatively, the contents of this file may be used under the
* terms of the GNU General Public License version 2 (the "GPL"), in
* which case the provisions of the GPL are applicable instead of the
* above. If you wish to allow the use of your version of this file
* only under the terms of the GPL and not to allow others to use your
* version of this file under the RHEPL, indicate your decision by
* deleting the provisions above and replace them with the notice and
* other provisions required by the GPL. If you do not delete the
* provisions above, a recipient may use your version of this file
* under either the RHEPL or the GPL.
*
* $Id: compr_rubin.c,v 1.2 2002/01/24 22:58:42 rfeany Exp $
*
*/
#include <config.h>
#include <jffs2/jffs2.h>
#include <jffs2/compr_rubin.h>
void rubin_do_decompress(unsigned char *bits, unsigned char *in,
unsigned char *page_out, __u32 destlen)
{
register char *curr = (char *)page_out;
char *end = (char *)(page_out + destlen);
register unsigned long temp;
register unsigned long result;
register unsigned long p;
register unsigned long q;
register unsigned long rec_q;
register unsigned long bit;
register long i0;
unsigned long i;
/* init_pushpull */
temp = *(u32 *) in;
bit = 16;
/* init_rubin */
q = 0;
p = (long) (2 * UPPER_BIT_RUBIN);
/* init_decode */
rec_q = (in[0] << 8) | in[1];
while (curr < end) {
/* in byte */
result = 0;
for (i = 0; i < 8; i++) {
/* decode */
while ((q & UPPER_BIT_RUBIN) || ((p + q) <= UPPER_BIT_RUBIN)) {
q &= ~UPPER_BIT_RUBIN;
q <<= 1;
p <<= 1;
rec_q &= ~UPPER_BIT_RUBIN;
rec_q <<= 1;
rec_q |= (temp >> (bit++ ^ 7)) & 1;
if (bit > 31) {
u32 *p = (u32 *)in;
bit = 0;
temp = *(++p);
in = (unsigned char *)p;
}
}
i0 = (bits[i] * p) >> 8;
if (i0 <= 0) i0 = 1;
/* if it fails, it fails, we have our crc
if (i0 >= p) i0 = p - 1; */
result >>= 1;
if (rec_q < q + i0) {
/* result |= 0x00; */
p = i0;
} else {
result |= 0x80;
p -= i0;
q += i0;
}
}
*(curr++) = result;
}
}
void dynrubin_decompress(unsigned char *data_in, unsigned char *cpage_out,
unsigned long sourcelen, unsigned long dstlen)
{
unsigned char bits[8];
int c;
for (c=0; c<8; c++)
bits[c] = (256 - data_in[c]);
rubin_do_decompress(bits, data_in+8, cpage_out, dstlen);
}
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