/* * JFFS2 -- Journalling Flash File System, Version 2. * * Copyright (C) 2001 Red Hat, Inc. * * Created by Arjan van de Ven <arjanv@redhat.com> * * 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_rtime.c,v 1.2 2002/01/24 22:58:42 rfeany Exp $ * * * Very simple lz77-ish encoder. * * Theory of operation: Both encoder and decoder have a list of "last * occurances" for every possible source-value; after sending the * first source-byte, the second byte indicated the "run" length of * matches * * The algorithm is intended to only send "whole bytes", no bit-messing. * */ #include <config.h> #include <jffs2/jffs2.h> void rtime_decompress(unsigned char *data_in, unsigned char *cpage_out, u32 srclen, u32 destlen) { int positions[256]; int outpos; int pos; int i; outpos = pos = 0; for (i = 0; i < 256; positions[i++] = 0); while (outpos<destlen) { unsigned char value; int backoffs; int repeat; value = data_in[pos++]; cpage_out[outpos++] = value; /* first the verbatim copied byte */ repeat = data_in[pos++]; backoffs = positions[value]; positions[value]=outpos; if (repeat) { if (backoffs + repeat >= outpos) { while(repeat) { cpage_out[outpos++] = cpage_out[backoffs++]; repeat--; } } else { for (i = 0; i < repeat; i++) *(cpage_out + outpos + i) = *(cpage_out + backoffs + i); outpos+=repeat; } } } }