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TbbTsqr_FillWithZerosTask.hpp
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00002 // ***********************************************************************
00003 //
00004 //                 Anasazi: Block Eigensolvers Package
00005 //                 Copyright (2010) Sandia Corporation
00006 //
00007 // Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
00008 // license for use of this work by or on behalf of the U.S. Government.
00009 //
00010 // This library is free software; you can redistribute it and/or modify
00011 // it under the terms of the GNU Lesser General Public License as
00012 // published by the Free Software Foundation; either version 2.1 of the
00013 // License, or (at your option) any later version.
00014 //
00015 // This library is distributed in the hope that it will be useful, but
00016 // WITHOUT ANY WARRANTY; without even the implied warranty of
00017 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00018 // Lesser General Public License for more details.
00019 //
00020 // You should have received a copy of the GNU Lesser General Public
00021 // License along with this library; if not, write to the Free Software
00022 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
00023 // USA
00024 // Questions? Contact Michael A. Heroux (maherou@sandia.gov)
00025 //
00026 // ***********************************************************************
00027 // @HEADER
00028 
00029 #ifndef __TSQR_TBB_FillWithZerosTask_hpp
00030 #define __TSQR_TBB_FillWithZerosTask_hpp
00031 
00032 #include <tbb/task.h>
00033 #include <TbbTsqr_Partitioner.hpp>
00034 #include <Tsqr_SequentialTsqr.hpp>
00035 
00038 
00039 namespace TSQR {
00040   namespace TBB {
00041     
00042     template< class LocalOrdinal, class Scalar >
00043     class FillWithZerosTask : public tbb::task {
00044     private:
00045       typedef MatView< LocalOrdinal, Scalar > mat_view;
00046       typedef std::pair< mat_view, mat_view > split_type;
00047 
00048     public:
00049       FillWithZerosTask (const size_t P_first, 
00050        const size_t P_last,
00051        MatView< LocalOrdinal, Scalar > C,
00052        const SequentialTsqr< LocalOrdinal, Scalar >& seq,
00053        const bool contiguous_cache_blocks = false)
00054   : P_first_ (P_first), 
00055     P_last_ (P_last), 
00056     C_ (C),
00057     seq_ (seq), 
00058     contiguous_cache_blocks_ (contiguous_cache_blocks)
00059       {}
00060 
00061       tbb::task* 
00062       execute () 
00063       {
00064   if (P_first_ > P_last_ || C_.empty())
00065     return NULL;
00066   else if (P_first_ == P_last_)
00067     {
00068       // Fill my partition with zeros.
00069       seq_.fill_with_zeros (C_.nrows(), C_.ncols(), C_.get(), 
00070           C_.lda(), contiguous_cache_blocks_);
00071       return NULL;
00072     }
00073   else
00074     {
00075       // "c": continuation task
00076       tbb::empty_task& c = *new( allocate_continuation() ) tbb::empty_task;
00077 
00078       // Recurse on two intervals: [P_first, P_mid] and [P_mid+1, P_last]
00079       const size_t P_mid = (P_first_ + P_last_) / 2;
00080       split_type C_split = 
00081         partitioner_.split (C_, P_first_, P_mid, P_last_, 
00082           contiguous_cache_blocks_);
00083       FillWithZerosTask& topTask = *new( c.allocate_child() )
00084         FillWithZerosTask (P_first_, P_mid, C_split.first, seq_, 
00085          contiguous_cache_blocks_);
00086       FillWithZerosTask& botTask = *new( c.allocate_child() )
00087         FillWithZerosTask (P_mid+1, P_last_, C_split.second, seq_, 
00088          contiguous_cache_blocks_);
00089 
00090       // Set reference count of parent (in this case, the
00091       // continuation task) to 2 (since 2 children -- no
00092       // additional task since no waiting).
00093       c.set_ref_count (2);
00094       c.spawn (botTask);
00095       return &topTask; // scheduler bypass optimization
00096     }
00097       }
00098 
00099     private:
00100       size_t P_first_, P_last_;
00101       mat_view C_;
00102       SequentialTsqr< LocalOrdinal, Scalar > seq_;
00103       Partitioner< LocalOrdinal, Scalar > partitioner_;
00104       bool contiguous_cache_blocks_;
00105     };
00106   } // namespace TBB
00107 } // namespace TSQR
00108 
00109 
00110 #endif // __TSQR_TBB_FillWithZerosTask_hpp
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