stapl::skeletons::skeletons_impl::reduce_to_pow_two_pd< Op > Class Template Reference

This parametric dependency is used in the preprocessing phase of various algorithms that only accept power-of-two input sizes. More...

Public Member Functions
	reduce_to_pow_two_pd (Op op)
template<typename Coord , typename Visitor , typename In >
void	case_of (Coord const &skeleton_size, Coord const &coord, Visitor &visitor, In &&in_flow) const
	If coord is <i, ...> it wraps the Op and sends it to the visitor. If q is the closest smaller power of two to n (r = n - q) and i < 2*r the following inputs are used: More...
template<typename Size , typename Coord , typename FlowIndex >
std::size_t	consumer_count (Size const &, Coord const &, FlowIndex) const
	Determines how many of the instances of this parametric dependency will be consuming from a producer with a given coordinate. This is a reverse query as compared to case_of. More...
Op	get_op () const
template<typename Coord >
int	get_result_id (Coord const &, Coord const &) const
template<typename Coord , typename Span >
void	configure (Coord &&, Span &&)

Public Types
using	op_type = Op

Static Public Attributes
static constexpr std::size_t	in_port_size = 1
static constexpr std::size_t	op_arity = 2

Detailed Description

template<typename Op>
class stapl::skeletons::skeletons_impl::reduce_to_pow_two_pd< Op >

This parametric dependency is used in the preprocessing phase of various algorithms that only accept power-of-two input sizes.

This method of size reduction is known as 2-to-1 preprocessing phase which is used in reduction algorithm. Basically, if the input size is n and the closest smaller power-of-two is m. The first 2*(n - m) = 2*r elements are combined given the Op in order to form r elements. The other r elements are just copied using the stapl::identity.

Template Parameters

Op	the workfunction to be applied on each pair of elements

Member Function Documentation

case_of()

template<typename Op >

template<typename Coord , typename Visitor , typename In >

void stapl::skeletons::skeletons_impl::reduce_to_pow_two_pd< Op >::case_of	(	Coord const &	skeleton_size,
		Coord const &	coord,
		Visitor &	visitor,
		In &&	in_flow
	)		const

If coord is <i, ...> it wraps the Op and sends it to the visitor. If q is the closest smaller power of two to n (r = n - q) and i < 2*r the following inputs are used:

• in<0>[i*2]
• in<0>[i*2 +1]

Otherwise identity is used with the following input:

• in<0>[i+r]

Parameters

skeleton_size	<n, m, p, ...> where each element is potentially multi-dimensional.
coord	<i, j, k, ...> where i < n, j < m, k < p
visitor	the information about Op and input is passed so that later this information can be converted to a node in the dependence graph
in_flow	a tuple of input flows to consume from

consumer_count()

template<typename Op >

template<typename Size , typename Coord , typename FlowIndex >

std::size_t stapl::skeletons::skeletons_impl::reduce_to_pow_two_pd< Op >::consumer_count	(	Size const &	,
		Coord const &	,
		FlowIndex
	)		const

Determines how many of the instances of this parametric dependency will be consuming from a producer with a given coordinate. This is a reverse query as compared to case_of.

Template Parameters

FlowIndex

the flow index to which this request is sent

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

• reduce_to_pow_two_pd.hpp