shuffle.cuh File Reference

Templated warp-shuffle operation variants. More...

#include <kat/on_device/common.cuh>
#include "detail/shuffle.cuh"

Functions
template<typename T >
KAT_FD T	kat::shuffle_arbitrary (const T &t, int source_lane)
	Have each lane in a warp get a value from an (arbitrary) other lane. More...
template<typename T >
KAT_FD T	kat::shuffle_down (const T &t, unsigned int delta)
template<typename T >
KAT_FD T	kat::shuffle_up (const T &t, unsigned int delta)
template<typename T >
KAT_FD T	kat::shuffle_xor (const T &t, int mask)
	Have pairs of lanes exchange a value, with the pairing performed by XORing bits of the lane index. More...

Detailed Description

Templated warp-shuffle operation variants.

Function Documentation

shuffle_arbitrary()

template<typename T >

KAT_FD T kat::shuffle_arbitrary	(	const T &	t,
		int	source_lane
	)

Have each lane in a warp get a value from an (arbitrary) other lane.

Template Parameters

T	the type of datum to be shared with other lane(s); may be of arbitrary size, but (at least for now) must be plain-old-data.

Parameters

t	Each lane shares own value, which other lanes can choose to receive.
source_lane	The lane whose value the current lane wants to get

Returns

the t value of source_lane

shuffle_down()

template<typename T >

KAT_FD T kat::shuffle_down	(	const T &	t,
		unsigned int	delta
	)

Parameters

t	Each lane shares own value, which a lane with a higher index will get.
delta	The difference in lane index to the source lane of the new value, i.e. a lane with index i gets the new value from lane i + delta.

Returns

The t value of the lane with index delta less than the calling lane's; a lane with a high index, above warp_size - delta, has its own t returned unchanged.

shuffle_up()

template<typename T >

KAT_FD T kat::shuffle_up	(	const T &	t,
		unsigned int	delta
	)

Template Parameters

T	the type of datum to be shared with other lane(s); may be of arbitrary size, but (at least for now) must be plain-old-data.

Parameters

t	Each lane shares own value, which a lane with a lower index will get.
delta	The difference in lane index to the source lane of the new value, i.e. a lane with index i gets the new value from the lane of index i - delta.

Returns

The t value of the lane with index delta less than the calling lane's; a lane with a low index, under delta, has its own t returned unchanged.

shuffle_xor()

template<typename T >

KAT_FD T kat::shuffle_xor	(	const T &	t,
		int	mask
	)

Have pairs of lanes exchange a value, with the pairing performed by XORing bits of the lane index.

Template Parameters

T	the type of datum to be shared with other lane(s); may be of arbitrary size, but (at least for now) must be plain-old-data.

Parameters

t	The value to exchange with a counterpart lane
mask	Determines how lanes will be paired: The lane with index i is paired with the lane with index i ^ mask.

Returns

The t value of the paired lane