Memory< V, Size1, Size2 > Class Template Reference

Detailed Description

template<typename V, size_t Size1, size_t Size2>
class Vc::Memory< V, Size1, Size2 >

A helper class for fixed-size two-dimensional arrays.

Parameters

V	The vector type you want to operate on. (e.g. float_v or uint_v)
Size1	Number of rows
Size2	Number of columns

#include <Vc/Memory>

Inherits VectorAlignedBaseT< V >, and MemoryBase< V, Memory< V, Size1, Size2 >, 2, Memory< V, Size2 > >.

Public Member Functions
constexpr size_t	rowsCount () const
constexpr size_t	entriesCount () const
constexpr size_t	vectorsCount () const
template<typename Parent , typename RM >
Memory &	operator= (const MemoryBase< V, Parent, 2, RM > &rhs)
	Copies the data from a different object.
Memory &	operator= (const V &v)
	Initialize all data with the given vector.
VectorPointerHelper< V, AlignedFlag >	vector (size_t i)
const VectorPointerHelperConst < V, AlignedFlag >	vector (size_t i) 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, A >	vectorAt (size_t i, A align=Vc::Aligned)
const VectorPointerHelperConst < V, A >	vectorAt (size_t i, A align=Vc::Aligned) 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

constexpr size_t rowsCount

(

)

const

Returns

the number of rows in the array.

Note

This function can be eliminated by an optimizing compiler.

constexpr size_t entriesCount

(

)

const

Returns

the number of scalar entries in the whole array.

Warning

Do not use this function for scalar iteration over the array since there will be padding between rows if Size2 is not divisible by V::Size.

Note

This function can be optimized into a compile-time constant.

Reimplemented from MemoryBase< V, Memory< V, Size1, Size2 >, 2, Memory< V, Size2 > >.

constexpr size_t vectorsCount

(

)

const

Returns

the number of vectors in the whole array.

Note

This function can be optimized into a compile-time constant.

Reimplemented from MemoryBase< V, Memory< V, Size1, Size2 >, 2, Memory< V, Size2 > >.

Memory& operator=

(

const MemoryBase< V, Parent, 2, RM > &

rhs

)

Copies the data from a different object.

Parameters

rhs	The object to copy the data from.

Returns

reference to the modified Memory object.

Note

Both objects must have the exact same vectorsCount().

Memory& operator=

(

const V &

v

)

Initialize all data with the given vector.

Parameters

v	This vector will be used to initialize the memory.

Returns

reference to the modified Memory object.

VectorPointerHelper<V, AlignedFlag> vector ( size_t  i )

inherited

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

inherited

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, UnalignedFlag> vector ( size_t  i, int  shift  )

inherited

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

inherited

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

inherited

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, AlignedFlag> firstVector ( )

inherited

Returns

the first vector in the allocated memory.

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

VectorPointerHelper<V, AlignedFlag> lastVector ( )

inherited

Returns

the last vector in the allocated memory.

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