PLMD::LoopUnroller< n > Class Template Reference

Utiliy class for loop unrolling. More...

#include <LoopUnroller.h>

Public Member Functions
template<>
void	_add (double *d, const double *a)
template<>
double	_dot (const double *d, const double *v)
template<>
void	_mul (double *d, const double s)
template<>
void	_neg (double *d, const double *a)
template<>
void	_sub (double *d, const double *a)
template<>
double	_sum2 (const double *d)
template<>
void	_zero (double *d)

Static Public Member Functions
static void	_add (double *d, const double *v)
	Add v to d. More...
static double	_dot (const double *d, const double *v)
	Dot product of d and v Same as r=0.0; for(unsigned i=0;i<n;i++) r+=d[i]*v[i]; return r; More...
static void	_mul (double *d, const double s)
	Multiply d by s. More...
static void	_neg (double *d, const double *v)
	Set d to -v. More...
static void	_sub (double *d, const double *v)
	Subtract v from d. More...
static double	_sum2 (const double *d)
	Squared modulo of d; Same as r=0.0; for(unsigned i=0;i<n;i++) r+=d[i]*d[i]; return r; More...
static void	_zero (double *d)
	Set to zero. More...

Detailed Description

template<unsigned n>
class PLMD::LoopUnroller< n >

Utiliy class for loop unrolling.

Many c++ compilers do not unroll small loops such as those used in the PLMD::Vector and PLMD::Tensor classes. This class provides methods to perform basic vector operations with unrolled loops. The methods work on double* so that they can be used in principles in other places of the code, but they are designed to be used in PLMD::Vector and PLMD::Tensor .

In case in the future we see that some compiler better optimize explicit loops, it should be easy to replace the methods here with loops. Alternatively, we could provide two paths using a cpp macro (e.g. __PLUMED_UNROLL_LOOPS or so).

All the methods for class LoopUnroller<n> act on n elements. Implementation is made using template metaprogramming, that is:

• LoopUnroller<1>::xxx acts on the element [0] of the array.
• LoopUnroller<n>::xxx calls LoopUnroller<n-1>::xxx then acts on element [n-1] of the array.

Here xxx is any of the methods of the class.

Member Function Documentation

_add() [1/2]

template<unsigned n>

void PLMD::LoopUnroller< n >::_add ( double *  d, const double *  v  )

static

Add v to d.

Same as for(unsigned i=0;i<n;i++) d[i]+=v[i];

_add() [2/2]

template<>

void PLMD::LoopUnroller< 1 >::_add ( double *  d, const double *  a  )

inline

_dot() [1/2]

template<unsigned n>

double PLMD::LoopUnroller< n >::_dot ( const double *  d, const double *  v  )

static

Dot product of d and v Same as r=0.0; for(unsigned i=0;i<n;i++) r+=d[i]*v[i]; return r;

_dot() [2/2]

template<>

double PLMD::LoopUnroller< 1 >::_dot ( const double *  d, const double *  v  )

inline

_mul() [1/2]

template<unsigned n>

void PLMD::LoopUnroller< n >::_mul ( double *  d, const double  s  )

static

Multiply d by s.

Same as for(unsigned i=0;i<n;i++) d[i]*=s;

_mul() [2/2]

template<>

void PLMD::LoopUnroller< 1 >::_mul ( double *  d, const double  s  )

inline

_neg() [1/2]

template<unsigned n>

void PLMD::LoopUnroller< n >::_neg ( double *  d, const double *  v  )

static

Set d to -v.

Same as for(unsigned i=0;i<n;i++) d[i]=-v[i];

_neg() [2/2]

template<>

void PLMD::LoopUnroller< 1 >::_neg ( double *  d, const double *  a  )

inline

_sub() [1/2]

template<unsigned n>

void PLMD::LoopUnroller< n >::_sub ( double *  d, const double *  v  )

static

Subtract v from d.

Same as for(unsigned i=0;i<n;i++) d[i]-=v[i];

_sub() [2/2]

template<>

void PLMD::LoopUnroller< 1 >::_sub ( double *  d, const double *  a  )

inline

_sum2() [1/2]

template<unsigned n>

double PLMD::LoopUnroller< n >::_sum2 ( const double *  d )

static

Squared modulo of d; Same as r=0.0; for(unsigned i=0;i<n;i++) r+=d[i]*d[i]; return r;

_sum2() [2/2]

template<>

double PLMD::LoopUnroller< 1 >::_sum2 ( const double *  d )

inline

_zero() [1/2]

template<unsigned n>

void PLMD::LoopUnroller< n >::_zero ( double *  d )

static

Set to zero.

Same as for(unsigned i=0;i<n;i++) d[i]=0.0;

_zero() [2/2]

template<>

void PLMD::LoopUnroller< 1 >::_zero ( double *  d )

inline

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

• tools/LoopUnroller.h