X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/1c080fdf88d3dc8cbf7413b1f8b3ce66d475070a..d47debaeffa6807956ee9cc7da90759efe49beda:/src/smpi/sample/ring_c.c

diff --git a/src/smpi/sample/ring_c.c b/src/smpi/sample/ring_c.c
new file mode 100644
index 0000000000..c301ab33b5
--- /dev/null
+++ b/src/smpi/sample/ring_c.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2004-2006 The Trustees of Indiana University and Indiana
+ *                         University Research and Technology
+ *                         Corporation.  All rights reserved.
+ * Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
+ *
+ * Simple ring test program
+ */
+
+#include <stdio.h>
+#include "mpi.h"
+
+int main(int argc, char *argv[])
+{
+    int rank, size, next, prev, message, tag = 201;
+
+    /* Start up MPI */
+
+    MPI_Init(&argc, &argv);
+    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+    MPI_Comm_size(MPI_COMM_WORLD, &size);
+ 
+    /* Calculate the rank of the next process in the ring.  Use the
+       modulus operator so that the last process "wraps around" to
+       rank zero. */
+
+    next = (rank + 1) % size;
+    prev = (rank + size - 1) % size;
+
+    /* If we are the "master" process (i.e., MPI_COMM_WORLD rank 0),
+       put the number of times to go around the ring in the
+       message. */
+
+    if (0 == rank) {
+        message = 10;
+
+        printf("Process 0 sending %d to %d, tag %d (%d processes in ring)\n", 
+               message, next, tag, size);
+        MPI_Send(&message, 1, MPI_INT, next, tag, MPI_COMM_WORLD); 
+        printf("Process 0 sent to %d\n", next);
+    }
+
+    /* Pass the message around the ring.  The exit mechanism works as
+       follows: the message (a positive integer) is passed around the
+       ring.  Each time it passes rank 0, it is decremented.  When
+       each processes receives a message containing a 0 value, it
+       passes the message on to the next process and then quits.  By
+       passing the 0 message first, every process gets the 0 message
+       and can quit normally. */
+
+    sleep(3);
+
+    while (1) {
+        MPI_Recv(&message, 1, MPI_INT, prev, tag, MPI_COMM_WORLD, 
+                 MPI_STATUS_IGNORE);
+
+        if (0 == rank) {
+            --message;
+            printf("Process 0 decremented value: %d\n", message);
+        }
+
+        MPI_Send(&message, 1, MPI_INT, next, tag, MPI_COMM_WORLD);
+        if (0 == message) {
+            printf("Process %d exiting\n", rank);
+            break;
+        }
+    }
+
+    /* The last process does one extra send to process 0, which needs
+       to be received before the program can exit */
+
+    if (0 == rank) {
+        MPI_Recv(&message, 1, MPI_INT, prev, tag, MPI_COMM_WORLD,
+                 MPI_STATUS_IGNORE);
+    }
+    
+    /* All done */
+
+    MPI_Finalize();
+    return 0;
+}