Diff: tvmet/loop/Gemtv.h

Revision:

15:9c5aaeda36dc

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tvmet/loop/Gemtv.h	Sat Apr 06 20:57:54 2013 +0000
@@ -0,0 +1,110 @@
+/*
+ * Tiny Vector Matrix Library
+ * Dense Vector Matrix Libary of Tiny size using Expression Templates
+ *
+ * Copyright (C) 2001 - 2007 Olaf Petzold <opetzold@users.sourceforge.net>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * $Id: Gemtv.h,v 1.7 2007-06-23 15:58:59 opetzold Exp $
+ */
+
+#ifndef TVMET_LOOP_GEMTV_H
+#define TVMET_LOOP_GEMTV_H
+
+namespace tvmet {
+
+namespace loop {
+
+
+/**
+ * \class gemtv Gemtv.h "tvmet/loop/Gemtv.h"
+ * \brief class for transposed(matrix)-vector product using loop unrolling.
+ *        using formula
+ *        \f[
+ *        M^T\,v
+ *        \f]
+ * \par Example:
+ * \code
+ * template<class T, std::size_t Rows, std::size_t Cols>
+ * inline
+ * void
+ * prod(const Matrix<T, Rows, Cols>& lhs, const Vector<T, Rows>& rhs,
+ *     Vector<T, Cols>& dest)
+ * {
+ *   for (std::size_t i = 0; i != Cols; ++i) {
+ *     dest(i) = tvmet::loop::gemtv<Rows, Cols>().prod(lhs, rhs, i);
+ *   }
+ * }
+ * \endcode
+ */
+template<std::size_t Rows, std::size_t Cols>
+class gemtv
+{
+  gemtv(const gemtv&);
+  gemtv& operator=(const gemtv&);
+
+private:
+  enum {
+    count     = Rows,
+    N         = (count+7)/8
+  };
+
+public:
+  gemtv() { }
+
+public:
+  template<class E1, class E2>
+  static inline
+  typename PromoteTraits<
+    typename E1::value_type,
+    typename E2::value_type
+    >::value_type
+  prod(const E1& lhs, const E2& rhs, std::size_t i) {
+    typename PromoteTraits<
+      typename E1::value_type,
+      typename E2::value_type
+    >::value_type                  sum(0);
+    std::size_t                 j(0);
+    std::size_t                 n(N);
+
+    // Duff's device
+    switch(count % 8) {
+    case 0: do { sum += lhs(j, i) * rhs(j); ++j;
+    case 7:      sum += lhs(j, i) * rhs(j); ++j;
+    case 6:      sum += lhs(j, i) * rhs(j); ++j;
+    case 5:      sum += lhs(j, i) * rhs(j); ++j;
+    case 4:      sum += lhs(j, i) * rhs(j); ++j;
+    case 3:      sum += lhs(j, i) * rhs(j); ++j;
+    case 2:      sum += lhs(j, i) * rhs(j); ++j;
+    case 1:      sum += lhs(j, i) * rhs(j); ++j;
+            } while(--n != 0);
+    }
+
+    return sum;
+  }
+};
+
+
+} // namespace loop
+
+} // namespace tvmet
+
+#endif /* TVMET_LOOP_GEMTV_H */
+
+// Local Variables:
+// mode:C++
+// tab-width:8
+// End: