eigen/Eigen/src/Core/util/BlasUtil.h

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2009 Gael Guennebaud <g.gael@free.fr>
//
// Eigen 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 3 of the License, or (at your option) any later version.
//
// Alternatively, you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of
// the License, or (at your option) any later version.
//
// Eigen 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 or the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License and a copy of the GNU General Public License along with
// Eigen. If not, see <http://www.gnu.org/licenses/>.

#ifndef EIGEN_BLASUTIL_H
#define EIGEN_BLASUTIL_H

// This file contains many lightweight helper classes used to
// implement and control fast level 2 and level 3 BLAS-like routines.

// forward declarations
template<typename Scalar, typename Packet, int PacketSize, int mr, int nr, typename Conj>
struct ei_gebp_kernel;

template<typename Scalar, int PacketSize, int nr>
struct ei_gemm_pack_rhs;

template<typename Scalar, int mr, int StorageOrder>
struct ei_gemm_pack_lhs;

template<
  typename Scalar,
  int LhsStorageOrder, bool ConjugateLhs,
  int RhsStorageOrder, bool ConjugateRhs,
  int ResStorageOrder>
struct ei_general_matrix_matrix_product;

template<bool ConjugateLhs, bool ConjugateRhs, typename Scalar, typename RhsType>
static void ei_cache_friendly_product_colmajor_times_vector(
  int size, const Scalar* lhs, int lhsStride, const RhsType& rhs, Scalar* res, Scalar alpha);

template<bool ConjugateLhs, bool ConjugateRhs, typename Scalar, typename ResType>
static void ei_cache_friendly_product_rowmajor_times_vector(
  const Scalar* lhs, int lhsStride, const Scalar* rhs, int rhsSize, ResType& res, Scalar alpha);

// Provides scalar/packet-wise product and product with accumulation
// with optional conjugation of the arguments.
template<bool ConjLhs, bool ConjRhs> struct ei_conj_helper;

template<> struct ei_conj_helper<false,false>
{
  template<typename T>
  EIGEN_STRONG_INLINE T pmadd(const T& x, const T& y, const T& c) const { return  ei_pmadd(x,y,c); }
  template<typename T>
  EIGEN_STRONG_INLINE T pmul(const T& x, const T& y) const { return  ei_pmul(x,y); }
};

template<> struct ei_conj_helper<false,true>
{
  template<typename T> std::complex<T>
  pmadd(const std::complex<T>& x, const std::complex<T>& y, const std::complex<T>& c) const
  { return c + pmul(x,y); }

  template<typename T> std::complex<T> pmul(const std::complex<T>& x, const std::complex<T>& y) const
  { return std::complex<T>(ei_real(x)*ei_real(y) + ei_imag(x)*ei_imag(y), ei_imag(x)*ei_real(y) - ei_real(x)*ei_imag(y)); }
};

template<> struct ei_conj_helper<true,false>
{
  template<typename T> std::complex<T>
  pmadd(const std::complex<T>& x, const std::complex<T>& y, const std::complex<T>& c) const
  { return c + pmul(x,y); }

  template<typename T> std::complex<T> pmul(const std::complex<T>& x, const std::complex<T>& y) const
  { return std::complex<T>(ei_real(x)*ei_real(y) + ei_imag(x)*ei_imag(y), ei_real(x)*ei_imag(y) - ei_imag(x)*ei_real(y)); }
};

template<> struct ei_conj_helper<true,true>
{
  template<typename T> std::complex<T>
  pmadd(const std::complex<T>& x, const std::complex<T>& y, const std::complex<T>& c) const
  { return c + pmul(x,y); }

  template<typename T> std::complex<T> pmul(const std::complex<T>& x, const std::complex<T>& y) const
  { return std::complex<T>(ei_real(x)*ei_real(y) - ei_imag(x)*ei_imag(y), - ei_real(x)*ei_imag(y) - ei_imag(x)*ei_real(y)); }
};

// lightweight helper class to access matrix coefficients
template<typename Scalar, int StorageOrder>
class ei_blas_data_mapper
{
  public:
    ei_blas_data_mapper(Scalar* data, int stride) : m_data(data), m_stride(stride) {}
    EIGEN_STRONG_INLINE Scalar& operator()(int i, int j)
    { return m_data[StorageOrder==RowMajor ? j + i*m_stride : i + j*m_stride]; }
  protected:
    Scalar* EIGEN_RESTRICT m_data;
    int m_stride;
};

// lightweight helper class to access matrix coefficients (const version)
template<typename Scalar, int StorageOrder>
class ei_const_blas_data_mapper
{
  public:
    ei_const_blas_data_mapper(const Scalar* data, int stride) : m_data(data), m_stride(stride) {}
    EIGEN_STRONG_INLINE const Scalar& operator()(int i, int j) const
    { return m_data[StorageOrder==RowMajor ? j + i*m_stride : i + j*m_stride]; }
  protected:
    const Scalar* EIGEN_RESTRICT m_data;
    int m_stride;
};

//
// template <int L2MemorySize,typename Scalar>
// struct ei_L2_block_traits {
//   enum {width = 8 * ei_meta_sqrt<L2MemorySize/(64*sizeof(Scalar))>::ret };
// };

// Defines various constant controlling level 3 blocking
template<typename Scalar>
struct ei_product_blocking_traits
{
  typedef typename ei_packet_traits<Scalar>::type PacketType;
  enum {
    PacketSize = sizeof(PacketType)/sizeof(Scalar),
    #if (defined __i386__)
    HalfRegisterCount = 4,
    #else
    HalfRegisterCount = 8,
    #endif

    // register block size along the N direction
    nr = HalfRegisterCount/2,

    // register block size along the M direction
    mr = 2 * PacketSize,

    // max cache block size along the K direction
    Max_kc = 8 * ei_meta_sqrt<EIGEN_TUNE_FOR_CPU_CACHE_SIZE/(64*sizeof(Scalar))>::ret,

    // max cache block size along the M direction
    Max_mc = 2*Max_kc
  };
};

#endif // EIGEN_BLASUTIL_H