56 lines
1.1 KiB
C
56 lines
1.1 KiB
C
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#include <mpi.h>
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#include <string.h>
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#include <stdio.h>
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#include "binom_reduce.h"
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void swap(void **a, void **b) {
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void *temp;
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temp = *a;
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*a = *b;
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*b = temp;
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}
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int Binom_Reduce(const void *sendbuf, void *recvbuf, int count,
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MPI_Datatype datatype, MPI_Op op, int root, MPI_Comm comm) {
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if (root != 0) {
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fprintf(stderr, "Sorry, root!=0 not allowed");
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return -1;
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}
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int r, p, size;
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MPI_Status status;
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void *recv;
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void *reduced;
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MPI_Comm_rank(comm, &r);
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MPI_Comm_size(comm, &p);
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MPI_Type_size(datatype, &size);
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MPI_Alloc_mem(count * size, MPI_INFO_NULL, &recv);
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MPI_Alloc_mem(count * size, MPI_INFO_NULL, &reduced);
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memcpy(reduced, sendbuf, count * size);
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int i = 1;
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while ((r + i) % (2 * i) != 0 && i < p) {
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if (r + i < p) {
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MPI_Recv(recv, count, datatype, r + i, i, comm, &status);
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MPI_Reduce_local(reduced, recv, count, datatype, op);
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swap(&reduced, &recv);
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}
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i <<= 1;
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}
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if (r != root) {
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MPI_Send(reduced, count, datatype, r - i, i, comm);
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} else {
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memcpy(recvbuf, reduced, count * size);
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}
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MPI_Free_mem(reduced);
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MPI_Free_mem(recv);
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return 0;
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}
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