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