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many2one.cpp
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Wed, Nov 13, 10:32

many2one.cpp
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#include "mpi.h"
#include "stdio.h"
#include "stdlib.h"
#include "many2one.h"
#include "memory.h"
/* ---------------------------------------------------------------------- */
Many2One::Many2One(MPI_Comm caller_comm)
{
comm = caller_comm;
MPI_Comm_rank(comm,&me);
MPI_Comm_size(comm,&nprocs);
memory = new Memory(comm);
if (me == 0) {
counts = new int[nprocs];
multicounts = new int[nprocs];
displs = new int[nprocs];
multidispls = new int[nprocs];
} else counts = multicounts = displs = multidispls = NULL;
idall = NULL;
}
/* ---------------------------------------------------------------------- */
Many2One::~Many2One()
{
delete memory;
delete [] counts;
delete [] multicounts;
delete [] displs;
delete [] multidispls;
memory->sfree(idall);
}
/* ---------------------------------------------------------------------- */
void Many2One::setup(int nsrc_in, int *id, int ndest)
{
nsrc = nsrc_in;
MPI_Allreduce(&nsrc,&nall,1,MPI_INT,MPI_SUM,comm);
MPI_Gather(&nsrc,1,MPI_INT,counts,1,MPI_INT,0,comm);
if (me == 0) {
displs[0] = 0;
for (int i = 1; i < nprocs; i++)
displs[i] = displs[i-1] + counts[i-1];
}
// gather IDs into idall
idall = NULL;
if (me == 0)
idall = (int *) memory->smalloc(nall*sizeof(int),"many2one:idall");
MPI_Gatherv(id,nsrc,MPI_INT,idall,counts,displs,MPI_INT,0,comm);
}
/* ---------------------------------------------------------------------- */
void Many2One::gather(double *src, int n, double *dest)
{
int i,j,ii,jj,m;
if (me == 0)
for (int i = 0; i < nprocs; i++) {
multicounts[i] = n*counts[i];
multidispls[i] = n*displs[i];
}
// allgather src into desttmp
double *desttmp = NULL;
if (me == 0)
desttmp = (double *) memory->smalloc(n*nall*sizeof(double),
"many2one:idsttmp");
MPI_Gatherv(src,n*nsrc,MPI_DOUBLE,desttmp,multicounts,multidispls,
MPI_DOUBLE,0,comm);
// use idall to move datums from desttmp to dest
if (me == 0) {
if (n == 1)
for (i = 0; i < nall; i++) {
j = idall[i] - 1;
dest[j] = desttmp[i];
}
else
for (i = 0; i < nall; i++) {
j = idall[i] - 1;
ii = n*i;
jj = n*j;
for (m = 0; m < n; m++)
dest[jj++] = desttmp[ii++];
}
}
memory->sfree(desttmp);
}

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