1 files changed, 86 insertions, 0 deletions
diff --git a/fs/jffs2/compr_rtime.c b/fs/jffs2/compr_rtime.c
new file mode 100644
index 0000000000..d74d7d3d79
--- /dev/null
+++ b/fs/jffs2/compr_rtime.c
@@ -0,0 +1,86 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2001-2007 Red Hat, Inc.
+ * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
+ *
+ * Created by Arjan van de Ven <arjanv@redhat.com>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ *
+ *
+ * Very simple lz77-ish encoder.
+ *
+ * Theory of operation: Both encoder and decoder have a list of "last
+ * occurrences" 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 <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/jffs2.h>
+#include "compr.h"
+
+static int jffs2_rtime_decompress(unsigned char *data_in,
+				  unsigned char *cpage_out,
+				  uint32_t srclen, uint32_t destlen)
+{
+	unsigned short positions[256];
+	int outpos = 0;
+	int pos=0;
+
+	memset(positions,0,sizeof(positions));
+
+	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 {
+				memcpy(&cpage_out[outpos],&cpage_out[backoffs],repeat);
+				outpos+=repeat;
+			}
+		}
+	}
+	return 0;
+}
+
+static struct jffs2_compressor jffs2_rtime_comp = {
+    .priority = JFFS2_RTIME_PRIORITY,
+    .name = "rtime",
+    .compr = JFFS2_COMPR_RTIME,
+    .decompress = &jffs2_rtime_decompress,
+#ifdef JFFS2_RTIME_DISABLED
+    .disabled = 1,
+#else
+    .disabled = 0,
+#endif
+};
+
+int jffs2_rtime_init(void)
+{
+    return jffs2_register_compressor(&jffs2_rtime_comp);
+}
+
+void jffs2_rtime_exit(void)
+{
+    jffs2_unregister_compressor(&jffs2_rtime_comp);
+}