86 lines
1.6 KiB
C
86 lines
1.6 KiB
C
/*
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* fib_reduce.c
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*
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* Created on: 18 Jun 2016
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* Author: johannes
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*/
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#include <stdio.h>
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#include <string.h>
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#include <mpi.h>
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#include "fib_reduce.h"
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int Fib_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_right;
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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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int temp;
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int right = 1;
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int fib = 1;
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while (fib - 1 < p) {
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temp = fib;
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fib += right;
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right = temp;
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}
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int left = fib - right;
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int i = 0;
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int parent = 0;
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while (i != r) {
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parent = i;
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if (r >= i + left) {
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i += left;
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temp = left;
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left = right - left;
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right = temp;
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} else {
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i++;
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right -= left;
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left -= right;
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}
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}
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if (r == root) {
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recv_right = recvbuf;
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} else {
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MPI_Alloc_mem(size * count, MPI_INFO_NULL, &recv_right);
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}
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if (right - 1 > 0 && r + 1 < p) {
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void *recv_left;
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MPI_Alloc_mem(count * size, MPI_INFO_NULL, &recv_left);
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MPI_Recv(recv_left, count, datatype, r + 1, 0, comm, &status);
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MPI_Reduce_local(sendbuf, recv_left, count, datatype, op);
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if (left - 1 > 0 && r + left < p) {
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MPI_Recv(recv_right, count, datatype, r + left, 0, comm, &status);
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MPI_Reduce_local(recv_left, recv_right, count, datatype, op);
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} else {
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memcpy(recv_right, recv_left, count * size);
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}
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MPI_Free_mem(recv_left);
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} else {
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memcpy(recv_right, sendbuf, count * size);
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}
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if (r != root) {
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MPI_Send(recv_right, count, datatype, parent, 0, comm);
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MPI_Free_mem(recv_right);
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}
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return 0;
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}
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