backend/lapack/mplapack/common.hpp

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#pragma once
 
#include <uni20/backend/blas/blas_int.hpp>
#include <uni20/config.hpp>
 
#if UNI20_HAS_MPLAPACK_FLOAT128
// clang-format off
#include <mplapack_config.h>
#include <mplapack_binary128.h>
// clang-format on
#endif
 
#include <algorithm>
#include <vector>
 
namespace uni20::lapack::mplapack::detail
{
 
#if UNI20_HAS_MPLAPACK_FLOAT128
 
inline std::size_t lapack_int_work_size(blas_int count)
{
  return static_cast<std::size_t>(std::max<blas_int>(1, count));
}
 
inline std::vector<mplapackint> make_mplapack_int_work(blas_int count)
{
  return std::vector<mplapackint>(lapack_int_work_size(count));
}
 
inline std::vector<mplapackint> to_mplapack_ints(blas_int const* values, blas_int count)
{
  std::vector<mplapackint> result = make_mplapack_int_work(count);
  for (blas_int i = 0; i < count; ++i)
  {
    result[static_cast<std::size_t>(i)] = static_cast<mplapackint>(values[i]);
  }
  return result;
}
 
inline void copy_from_mplapack_ints(std::vector<mplapackint> const& source, blas_int* target, blas_int count)
{
  for (blas_int i = 0; i < count; ++i)
  {
    target[i] = static_cast<blas_int>(source[static_cast<std::size_t>(i)]);
  }
}
 
inline void copy_from_mplapack_query_int_work(std::vector<mplapackint> const& source, blas_int* target, blas_int lwork)
{
  if (target == nullptr || (lwork != -1 && lwork <= 0))
  {
    return;
  }
  copy_from_mplapack_ints(source, target, 1);
}
 
using uni20::blas::checked_blas_int;
 
inline blas_int gelsd_iwork_size(blas_int m, blas_int n)
{
  blas_int const minmn = std::min(m, n);
  if (minmn <= 0)
  {
    return 1;
  }
 
  // LAPACK's bound uses SMLSIZ from ILAENV. Using divisor 2 overestimates the
  // subdivision depth, avoiding a runtime dependency on ILAENV in this wrapper.
  std::size_t levels = 0;
  for (std::size_t size = static_cast<std::size_t>(minmn) / 2; size > 0; size /= 2)
  {
    ++levels;
  }
  std::size_t const minmn_size = static_cast<std::size_t>(minmn);
  std::size_t const required = 3 * minmn_size * levels + 11 * minmn_size;
  return checked_blas_int(std::max<std::size_t>(1, required));
}
 
#endif
 
} // namespace uni20::lapack::mplapack::detail