sdfg::tiles::Swizzle Struct Reference

XOR-swizzle as a composition functor over a Layout. More...

#include <sdfg/tiles/swizzle.h>

Public Member Functions
bool	is_identity () const
symbolic::Expression	apply (const symbolic::Expression &offset) const
	Permute a linear offset (a symbolic bit_xor of shifted/masked fields).
bool	operator== (const Swizzle &other) const

Public Attributes
int	bits = 0
	B: width of the swizzled field (0 = identity).
int	base = 0
	M: low bit position left untouched below the field.
int	shift = 0
	S: distance between the two fields (sign = direction).

Detailed Description

XOR-swizzle as a composition functor over a Layout.

XOR is nonlinear, so a swizzle is not a (shape, stride) layout; following CuTe's Swizzle<B, M, S> it rides on top of a layout's offset. Applied identically to writes and reads, it is a pure relabelling (bank spreading).

Swizzle{bits=B, base=M, shift=S} XORs the B-bit field at position M with the field at M + |S|: yyy = (o >> (M + |S|)) & ((1 << B) - 1); o' = o XOR (yyy << M) an involution; bits == 0 is the identity.

Member Function Documentation

apply()

symbolic::Expression sdfg::tiles::Swizzle::apply

(

const symbolic::Expression &

offset

)

const

Permute a linear offset (a symbolic bit_xor of shifted/masked fields).

is_identity()

bool sdfg::tiles::Swizzle::is_identity ( ) const

inline

operator==()

bool sdfg::tiles::Swizzle::operator== ( const Swizzle & other ) const

inline

Member Data Documentation

base

int sdfg::tiles::Swizzle::base = 0

M: low bit position left untouched below the field.

bits

int sdfg::tiles::Swizzle::bits = 0

B: width of the swizzled field (0 = identity).

shift

int sdfg::tiles::Swizzle::shift = 0

S: distance between the two fields (sign = direction).

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

• opt/include/sdfg/tiles/swizzle.h