1 files changed, 132 insertions, 0 deletions

diff --git a/fs/jffs2/compr_rtime.c b/fs/jffs2/compr_rtime.c
new file mode 100644
index 000000000000..393129418666
--- /dev/null
+++ b/fs/jffs2/compr_rtime.c
@@ -0,0 +1,132 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright (C) 2001-2003 Red Hat, Inc.
+ *
+ * Created by Arjan van de Ven <arjanv@redhat.com>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ * $Id: compr_rtime.c,v 1.14 2004/06/23 16:34:40 havasi Exp $
+ *
+ *
+ * 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/errno.h>
+#include <linux/string.h> 
+#include <linux/jffs2.h> 
+#include "compr.h"
+
+/* _compress returns the compressed size, -1 if bigger */
+static int jffs2_rtime_compress(unsigned char *data_in,
+                                unsigned char *cpage_out,
+                                uint32_t *sourcelen, uint32_t *dstlen,
+                                void *model)
+{
+        short positions[256];
+        int outpos = 0;
+        int pos=0;
+
+        memset(positions,0,sizeof(positions)); 
+        
+        while (pos < (*sourcelen) && outpos <= (*dstlen)-2) {
+                int backpos, runlen=0;
+                unsigned char value;
+                
+                value = data_in[pos];
+
+                cpage_out[outpos++] = data_in[pos++];
+                
+                backpos = positions[value];
+                positions[value]=pos;
+                
+                while ((backpos < pos) && (pos < (*sourcelen)) &&
+                       (data_in[pos]==data_in[backpos++]) && (runlen<255)) {
+                        pos++;
+                        runlen++;
+                }
+                cpage_out[outpos++] = runlen;
+        }
+
+        if (outpos >= pos) {
+                /* We failed */
+                return -1;
+        }
+        
+        /* Tell the caller how much we managed to compress, and how much space it took */
+        *sourcelen = pos;
+        *dstlen = outpos;
+        return 0;
+}                  
+
+
+static int jffs2_rtime_decompress(unsigned char *data_in,
+                                  unsigned char *cpage_out,
+                                  uint32_t srclen, uint32_t destlen,
+                                  void *model)
+{
+        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,
+    .compress = &jffs2_rtime_compress,
+    .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);
+}