MemoryBase< V, Parent, Dimension, RowMemory > Class Template Reference

Detailed Description

template<typename V, typename Parent, int Dimension, typename RowMemory>
class Vc::MemoryBase< V, Parent, Dimension, RowMemory >

Common interface to all Memory classes, independent of allocation on the stack or heap.

Parameters

V	The vector type you want to operate on. (e.g. float_v or uint_v)
Parent	This type is the complete type of the class that derives from MemoryBase.
Dimension	The number of dimensions the implementation provides.
RowMemory	Class to be used to work on a single row.

#include <Vc/Memory>

Inherits MemoryDimensionBase< V, Parent, Dimension, RowMemory >.

Public Types
typedef V::EntryType	EntryType
	The type of the scalar entries in the array.

Public Member Functions
size_t	entriesCount () const
size_t	vectorsCount () const
VectorPointerHelper< V, AlignedFlag >	vector (size_t i)
const VectorPointerHelperConst < V, AlignedFlag >	vector (size_t i) const
	Const overload of the above function.
template<typename A >
VectorPointerHelper< V, A >	vectorAt (size_t i, A align=Vc::Aligned)
template<typename A >
const VectorPointerHelperConst < V, A >	vectorAt (size_t i, A align=Vc::Aligned) const
	Const overload of the above function.
VectorPointerHelper< V, UnalignedFlag >	vector (size_t i, int shift)
const VectorPointerHelperConst < V, UnalignedFlag >	vector (size_t i, int shift) const
	Const overload of the above function.
VectorPointerHelper< V, AlignedFlag >	firstVector ()
const VectorPointerHelperConst < V, AlignedFlag >	firstVector () const
	Const overload of the above function.
VectorPointerHelper< V, AlignedFlag >	lastVector ()
const VectorPointerHelperConst < V, AlignedFlag >	lastVector () const
	Const overload of the above function.

Member Function Documentation

size_t entriesCount

(

)

const

Returns

the number of scalar entries in the array. This function is optimized away if a constant size array is used.

Reimplemented in Memory< V, 0u, 0u >, Memory< V, Size, 0u >, and Memory< V, Size1, Size2 >.

size_t vectorsCount

(

)

const

Returns

the number of vector entries that span the array. This function is optimized away if a constant size array is used.

Reimplemented in Memory< V, 0u, 0u >, Memory< V, Size, 0u >, and Memory< V, Size1, Size2 >.

VectorPointerHelper<V, AlignedFlag> vector

(

size_t

i

)

Parameters

i	Selects the offset, where the vector should be read.

Returns

a smart object to wrap the i-th vector in the memory.

The return value can be used as any other vector object. I.e. you can substitute something like

float_v a = ..., b = ...;
a += b;

with

mem.vector(i) += b;

This function ensures that only aligned loads and stores are used. Thus it only allows to access memory at fixed strides. If access to known offsets from the aligned vectors is needed the vector(size_t, int) function can be used.

const VectorPointerHelperConst<V, AlignedFlag> vector

(

size_t

i

)

const

Const overload of the above function.

Parameters

i	Selects the offset, where the vector should be read.

Returns

a smart object to wrap the i-th vector in the memory.

VectorPointerHelper<V, A> vectorAt	(	size_t	i,
		A	align = Vc::Aligned
	)

Returns

a smart object to wrap the vector starting from the i-th scalar entry in the memory.

Example:

Memory<float_v, N> mem;
mem.setZero();
for (int i = 0; i < mem.entriesCount(); i += float_v::Size) {
    mem.vectorAt(i) += b;
}

Parameters

i	Specifies the scalar entry from where the vector will be loaded/stored. I.e. the values scalar(i), scalar(i + 1), ..., scalar(i + V::Size - 1) will be read/overwritten.
align	You must take care to determine whether an unaligned load/store is required. Per default an aligned load/store is used. If i is not a multiple of V::Size you must pass Vc::Unaligned here.

const VectorPointerHelperConst<V, A> vectorAt	(	size_t	i,
		A	align = Vc::Aligned
	)		const

Const overload of the above function.

Returns

a smart object to wrap the vector starting from the i-th scalar entry in the memory.

Parameters

i	Specifies the scalar entry from where the vector will be loaded/stored. I.e. the values scalar(i), scalar(i + 1), ..., scalar(i + V::Size - 1) will be read/overwritten.
align	You must take care to determine whether an unaligned load/store is required. Per default an aligned load/store is used. If i is not a multiple of V::Size you must pass Vc::Unaligned here.

VectorPointerHelper<V, UnalignedFlag> vector	(	size_t	i,
		int	shift
	)

Returns

a smart object to wrap the i-th vector + shift in the memory.

This function ensures that only unaligned loads and stores are used. It allows to access memory at any location aligned to the entry type.

Parameters

i	Selects the memory location of the i-th vector. Thus if V::Size == 4 and i is set to 3 the base address for the load/store will be the 12th entry (same as &mem[12]).
shift	Shifts the base address determined by parameter i by shift many entries. Thus vector(3, 1) for V::Size == 4 will load/store the 13th - 16th entries (same as &mem[13]).

Note

Any shift value is allowed as long as you make sure it stays within bounds of the allocated memory. Shift values that are a multiple of V::Size will not result in aligned loads. You have to use the above vector(size_t) function for aligned loads instead.

Thus a simple way to access vectors randomly is to set i to 0 and use shift as the parameter to select the memory address:

// don't use:
mem.vector(i / V::Size, i % V::Size) += 1;
// instead use:
mem.vector(0, i) += 1;

VectorPointerHelper<V, AlignedFlag> firstVector

(

)

Returns

the first vector in the allocated memory.

This function is simply a shorthand for vector(0).

VectorPointerHelper<V, AlignedFlag> lastVector

(

)

Returns

the last vector in the allocated memory.

This function is simply a shorthand for vector(vectorsCount() - 1).