Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / fs / jffs2 / compr_rtime.c

diff --git a/kernel/fs/jffs2/compr_rtime.c b/kernel/fs/jffs2/compr_rtime.c
new file mode 100644 (file)
index 0000000..406d9cc
--- /dev/null
+++ b/kernel/fs/jffs2/compr_rtime.c
@@ -0,0 +1,130 @@
+/*
+ * 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/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)
+{
+       unsigned 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)
+{
+       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,
+    .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);
+}