walberla::stencil::$name Struct Reference

Detailed Description

Defines a D-dimensional stencil info with Q directions.

A stencil is defined by picking a subset of all possible directions. These directions are listed in the dir array. So when iterating a stencil, one iterates the dir array which contains the directions. To get the properties for these directions, the global arrays of Directions.h can be used:

using namespace stencil;
for( uint_t i = 0; i < $name::Size; ++i )
{
   int cx = cx[ $name::dir[i] ];
   Direction inverse = inverseDir[ $name::dir[i] ];
}

Since all these arrays are constant, the lookup can be resolved at compile time and no performance overhead should be generated.

For more convenient iteration, use the provided iterator. The following code is equivalent to the code example above:

using namespace stencil;
for( auto dir = $name::begin(); dir != $name::end(); ++dir )
{
  int cx = dir.cx();
  Direction inverse = dir.inverseDir();
}

#include <Stencil.in.h>

Iteration
using	iterator = stencil::Iterator< $name >
static constexpr iterator	begin ()
static constexpr iterator	beginNoCenter ()
static constexpr iterator	end ()

Member Variables
static constexpr std::string_view	NAME = "$name"
static constexpr uint_t	D = $D
static constexpr uint_t	Q = $Q
static constexpr uint_t	POS_Q = $Q / 2
static constexpr uint_t	Dimension = $D
static constexpr uint_t	Size = $Q
static constexpr bool	containsCenter = $containsCenter
static constexpr uint_t	noCenterFirstIdx = $noCenterFirstIndex
static constexpr std::array< Direction, $Q >	dir = { $dirs }
	Set of directions.
static constexpr std::array< Direction, POS_Q >	dir_pos = { $dir_pos }
	Contains only half of the directions ( the positive ones ).
static constexpr std::array< uint_t, NR_OF_DIRECTIONS >	idx = { $indexFromDir }
	Maps direction enums, to an index.
static constexpr std::array< std::array< Direction, $Q/2 >, NR_OF_DIRECTIONS >	d_per_d { { $d_per_d } }
	Maps a direction to a set of sub-directions.
static constexpr std::array< uint_t, NR_OF_DIRECTIONS >	d_per_d_length { $d_per_d_length }
	Length of the d_per_d array For usage see documentation of d_per_d.
static constexpr size_t	subdirsLength { $subdirs_length }
static constexpr std::array< Direction, $subdirs_length >	subdirs { $subdirs }
static constexpr std::array< size_t, NR_OF_DIRECTIONS+1 >	subdirsPtr { $subdirsPtr }
static constexpr std::array< std::array< Direction, NR_OF_DIRECTIONS >, NR_OF_DIRECTIONS >	dir_neighbors { { $dir_neighbors } }
	Views directions as cells in a 3x3x3 grid.
static constexpr std::array< uint_t, NR_OF_DIRECTIONS >	dir_neighbors_length { $dir_neighbors_length }
	Length of the dir_neighbors array For usage see documentation of dir_neighbors.
static constexpr bool	containsDir (Direction d)
static constexpr uint_t	invDirIdx (Direction d)

Member Typedef Documentation

iterator

using walberla::stencil::$name::iterator = stencil::Iterator< $name >

Member Function Documentation

begin()

constexpr iterator walberla::stencil::$name::begin ( )

inlinestaticconstexpr

beginNoCenter()

constexpr iterator walberla::stencil::$name::beginNoCenter ( )

inlinestaticconstexpr

containsDir()

constexpr bool walberla::stencil::$name::containsDir ( Direction d )

inlinestaticconstexpr

end()

constexpr iterator walberla::stencil::$name::end ( )

inlinestaticconstexpr

invDirIdx()

constexpr uint_t walberla::stencil::$name::invDirIdx ( Direction d )

inlinestaticconstexpr

Member Data Documentation

containsCenter

bool walberla::stencil::$name::containsCenter = $containsCenter

staticconstexpr

D

uint_t walberla::stencil::$name::D = $D

staticconstexpr

d_per_d

std::array< std::array< Direction, $Q / 2 >, NR_OF_DIRECTIONS > walberla::stencil::$name::d_per_d { { $d_per_d } }

staticconstexpr

Maps a direction to a set of sub-directions.

A sub-direction is defined as a direction that contains the letters of the original direction i.e. SW is a sub-direction of S and W. the following code shows how to iterate over all sub-directions, that are contained in the stencil of W

template<typename Stencil>
//...
stencil::Direction dir = stencil::W;
for (int i=0; i < Stencil::d_per_d_length[dir]; ++i)
   stencil::Direction subDirection = Stencil::d_per_d[dir][i];

d_per_d_length

std::array< uint_t, NR_OF_DIRECTIONS > walberla::stencil::$name::d_per_d_length { $d_per_d_length }

staticconstexpr

Length of the d_per_d array For usage see documentation of d_per_d.

Dimension

uint_t walberla::stencil::$name::Dimension = $D

staticconstexpr

dir

std::array< Direction, $Q > walberla::stencil::$name::dir = { $dirs }

staticconstexpr

Set of directions.

dir_neighbors

std::array< std::array< Direction, NR_OF_DIRECTIONS >, NR_OF_DIRECTIONS > walberla::stencil::$name::dir_neighbors { { $dir_neighbors } }

staticconstexpr

Views directions as cells in a 3x3x3 grid.

Describes neighborhood between cells/directions.

Basis a 3x3x3 grid where every cell corresponds to a direction. The following array provides answer to the question: What are the neighboring cells of a given cell using the current stencil. If a neighbor is not in this 3x3x3 grid it can not be described by a direction and is not returned. Therefore N , for example, has more neighbors that NW. By definition, the neighbors of C are identical to the dir[] array without C itself.

dir_neighbors_length

std::array< uint_t, NR_OF_DIRECTIONS > walberla::stencil::$name::dir_neighbors_length { $dir_neighbors_length }

staticconstexpr

Length of the dir_neighbors array For usage see documentation of dir_neighbors.

dir_pos

std::array< Direction, POS_Q > walberla::stencil::$name::dir_pos = { $dir_pos }

staticconstexpr

Contains only half of the directions ( the positive ones ).

Use this f.e. in situations where direction have to be handled pairwise, the direction together with its inverse direction.

idx

std::array< uint_t, NR_OF_DIRECTIONS > walberla::stencil::$name::idx = { $indexFromDir }

staticconstexpr

Maps direction enums, to an index.

Use this when working with fields: The direction enum cannot be used as field index directly. Consider having a D2Q4 stencil, then the fourth field index f ranges from 0 to 3, but the direction enums are S=1,N=2,E=3,W=4 start at 1. So a stencil class is needed to map back from direction to field index

NAME

std::string_view walberla::stencil::$name::NAME = "$name"

staticconstexpr

noCenterFirstIdx

uint_t walberla::stencil::$name::noCenterFirstIdx = $noCenterFirstIndex

staticconstexpr

POS_Q

uint_t walberla::stencil::$name::POS_Q = $Q / 2

staticconstexpr

Q

uint_t walberla::stencil::$name::Q = $Q

staticconstexpr

Size

uint_t walberla::stencil::$name::Size = $Q

staticconstexpr

subdirs

std::array< Direction, $subdirs_length > walberla::stencil::$name::subdirs { $subdirs }

staticconstexpr

subdirsLength

size_t walberla::stencil::$name::subdirsLength { $subdirs_length }

staticconstexpr

subdirsPtr

std::array< size_t, NR_OF_DIRECTIONS + 1 > walberla::stencil::$name::subdirsPtr { $subdirsPtr }

staticconstexpr

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The documentation for this struct was generated from the following file:

• /builds/administration/walberla-website/walberla/src/stencil/Stencil.in.h