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-rw-r--r--nxcomp/BlockCache.cpp69
1 files changed, 69 insertions, 0 deletions
diff --git a/nxcomp/BlockCache.cpp b/nxcomp/BlockCache.cpp
new file mode 100644
index 000000000..f885290f0
--- /dev/null
+++ b/nxcomp/BlockCache.cpp
@@ -0,0 +1,69 @@
+/**************************************************************************/
+/* */
+/* Copyright (c) 2001, 2010 NoMachine, http://www.nomachine.com/. */
+/* */
+/* NXCOMP, NX protocol compression and NX extensions to this software */
+/* are copyright of NoMachine. Redistribution and use of the present */
+/* software is allowed according to terms specified in the file LICENSE */
+/* which comes in the source distribution. */
+/* */
+/* Check http://www.nomachine.com/licensing.html for applicability. */
+/* */
+/* NX and NoMachine are trademarks of Medialogic S.p.A. */
+/* */
+/* All rights reserved. */
+/* */
+/**************************************************************************/
+
+#include <string.h>
+#include "BlockCache.h"
+
+
+int BlockCache::compare(unsigned int size, const unsigned char *data,
+ int overwrite)
+{
+ int match = 0;
+ if (size == size_)
+ {
+ match = 1;
+ for (unsigned int i = 0; i < size_; i++)
+ if (data[i] != buffer_[i])
+ {
+ match = 0;
+ break;
+ }
+ }
+ if (!match && overwrite)
+ set(size, data);
+ return match;
+}
+
+
+void BlockCache::set(unsigned int size, const unsigned char *data)
+{
+ if (size_ < size)
+ {
+ delete[]buffer_;
+ buffer_ = new unsigned char[size];
+ }
+ size_ = size;
+ memcpy(buffer_, data, size);
+ checksum_ = checksum(size, data);
+}
+
+
+unsigned int BlockCache::checksum(unsigned int size, const unsigned char *data)
+{
+ unsigned int sum = 0;
+ unsigned int shift = 0;
+ const unsigned char *next = data;
+ for (unsigned int i = 0; i < size; i++)
+ {
+ unsigned int value = (unsigned int) *next++;
+ sum += (value << shift);
+ shift++;
+ if (shift == 8)
+ shift = 0;
+ }
+ return sum;
+}