1 files changed, 91 insertions, 0 deletions
diff --git a/fs/jffs2/compr_rtime.c b/fs/jffs2/compr_rtime.c
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+++ b/fs/jffs2/compr_rtime.c
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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>
+ *
+ * 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>
+#if (CONFIG_COMMANDS & CFG_CMD_JFFS2)
+
+#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;
+			}
+		}
+	}
+}
+
+#endif /* CFG_CMD_JFFS2 */