/*
   * 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);
  }