From ce7e11c41b5f24e0e90f9432fa6c0567a8a12750 Mon Sep 17 00:00:00 2001
From: Johannes Winklehner <johannes.winklehner@gmail.com>
Date: Thu, 16 Jun 2016 17:45:55 +0200
Subject: [PATCH] Binary Tree Reduce wird bald funktionieren

---
 hpc_mpi/src/bin_reduce.c | 64 ++++++++++++++++++++++++++++++++++++++++
 hpc_mpi/src/bin_reduce.h | 14 +++++++++
 hpc_mpi/src/hpc_mpi.c    | 13 ++++++--
 3 files changed, 89 insertions(+), 2 deletions(-)
 create mode 100644 hpc_mpi/src/bin_reduce.c
 create mode 100644 hpc_mpi/src/bin_reduce.h

diff --git a/hpc_mpi/src/bin_reduce.c b/hpc_mpi/src/bin_reduce.c
new file mode 100644
index 0000000..fce1f0f
--- /dev/null
+++ b/hpc_mpi/src/bin_reduce.c
@@ -0,0 +1,64 @@
+/*
+ * bin_reduce.c
+ *
+ *  Created on: 16 Jun 2016
+ *      Author: johannes
+ */
+
+#include <stdio.h>
+#include "mpi.h"
+#include "bin_reduce.h"
+
+int int_log2(int x) {
+	int r;
+	while (x >>= 1) {
+		r++;
+	}
+	return r;
+}
+
+int Bin_Reduce(const void *sendbuf, void *recvbuf, int count,
+		MPI_Datatype datatype, MPI_Op op, int root, MPI_Comm comm) {
+	if (root != 0) {
+		fprintf(stderr, "Sorry, root!=0 not allowed");
+		return -1;
+	}
+
+	int r, p;
+
+	MPI_Comm_rank(comm, &r);
+	MPI_Comm_size(comm, &p);
+
+	int tree_depth = int_log2(p);
+	int i = 0;
+	int depth;
+	int parent = 0;
+
+	// maximum possible number of nodes with current depth
+	int max_nodes = (1 << (tree_depth + 1)) - 1;
+
+	for (depth = 1; i != r; depth++) {
+		parent = i;
+		max_nodes /= 2;
+		if (r > i + max_nodes) {
+			i += max_nodes + 1;
+		} else {
+			i++;
+		}
+	}
+
+	printf("%i: %i\n", r, parent);
+
+	/*if (depth != tree_depth) {
+	 MPI_Recv();
+	 MPI_Reduce_local();
+	 MPI_Recv();
+	 MPI_Reduce_local();
+	 }
+
+	 if (r != root) {
+	 MPI_Send();
+	 }*/
+
+	return 0;
+}
diff --git a/hpc_mpi/src/bin_reduce.h b/hpc_mpi/src/bin_reduce.h
new file mode 100644
index 0000000..aa421b0
--- /dev/null
+++ b/hpc_mpi/src/bin_reduce.h
@@ -0,0 +1,14 @@
+/*
+ * bin_reduce.h
+ *
+ *  Created on: 16 Jun 2016
+ *      Author: johannes
+ */
+
+#ifndef BIN_REDUCE_H_
+#define BIN_REDUCE_H_
+
+int Bin_Reduce(const void *sendbuf, void *recvbuf, int count,
+		MPI_Datatype datatype, MPI_Op op, int root, MPI_Comm comm);
+
+#endif /* BIN_REDUCE_H_ */
diff --git a/hpc_mpi/src/hpc_mpi.c b/hpc_mpi/src/hpc_mpi.c
index 7776d2e..58a1710 100644
--- a/hpc_mpi/src/hpc_mpi.c
+++ b/hpc_mpi/src/hpc_mpi.c
@@ -10,6 +10,7 @@
 #include <stdio.h>
 #include <string.h>
 #include "mpi.h"
+#include "bin_reduce.h"
 
 int Binom_Reduce(const void *sendbuf, void *recvbuf, int count,
 		MPI_Datatype datatype, MPI_Op op, int root, MPI_Comm comm);
@@ -31,10 +32,12 @@ int main(int argc, char* argv[]) {
 	int a = my_rank;
 	int recv;
 
-	Binom_Reduce(&a, &recv, 1, MPI_INT, MPI_SUM, 0, MPI_COMM_WORLD);
+	Bin_Reduce(&a, &recv, 1, MPI_INT, MPI_SUM, 0, MPI_COMM_WORLD);
+
+	//Binom_Reduce(&a, &recv, 1, MPI_INT, MPI_SUM, 0, MPI_COMM_WORLD);
 
 	if (my_rank == 0) {
-		printf("%i\n", recv);
+		//printf("%i\n", recv);
 	}
 	/* shut down MPI */
 	MPI_Finalize();
@@ -79,3 +82,9 @@ int Binom_Reduce(const void *sendbuf, void *recvbuf, int count,
 
 	return 0;
 }
+
+int Fib_Reduce(const void *sendbuf, void *recvbuf, int count,
+		MPI_Datatype datatype, MPI_Op op, int root, MPI_Comm comm) {
+	return 0;
+}
+