}
+/**
+ * MPI_Scatter user entry point
+ **/
+//int SMPI_MPI_Scatter(void *sendbuf, int sendcount, MPI_Datatype datatype,
+// void *recvbuf, int recvcount, MPI_Datatype recvtype,int root,
+// MPI_Comm comm);
+int SMPI_MPI_Scatter(void *sendbuf, int sendcount, MPI_Datatype datatype,
+ void *recvbuf, int recvcount, MPI_Datatype recvtype,
+ int root, MPI_Comm comm)
+{
+ int retval = MPI_SUCCESS;
+ int i;
+ int cnt=0;
+ int rank;
+ int tag=0;
+ char *cbuf; // to manipulate the void * buffers
+ smpi_mpi_request_t *requests;
+ smpi_mpi_request_t request;
+ smpi_mpi_status_t status;
+
+
+ smpi_bench_end();
+
+ rank = smpi_mpi_comm_rank(comm);
+
+ requests = xbt_malloc((comm->size-1) * sizeof(smpi_mpi_request_t));
+ if (rank == root) {
+ // i am the root: distribute my sendbuf
+ for (i=0; i < comm->size; i++) {
+ cbuf = sendbuf;
+ cbuf += i*sendcount*datatype->size;
+ if ( i!=root ) { // send to processes ...
+
+ retval = smpi_create_request((void *)cbuf, sendcount,
+ datatype, root, i, tag, comm, &(requests[cnt++]));
+ if (NULL != requests[cnt] && MPI_SUCCESS == retval) {
+ if (MPI_SUCCESS == retval) {
+ smpi_mpi_isend(requests[cnt]);
+ }
+ }
+ cnt++;
+ }
+ else { // ... except if it's me.
+ memcpy(recvbuf, (void *)cbuf, recvcount*recvtype->size*sizeof(char));
+ }
+ }
+ for(i=0; i<cnt; i++) { // wait for send to complete
+ /* FIXME: waitall() should be slightly better */
+ smpi_mpi_wait(requests[i], &status);
+ xbt_mallocator_release(smpi_global->request_mallocator, requests[i]);
+
+ }
+ }
+ else { // i am a non-root process: wait data from the root
+ retval = smpi_create_request(recvbuf,recvcount,
+ recvtype, root, rank, tag, comm, &request);
+ if (NULL != request && MPI_SUCCESS == retval) {
+ if (MPI_SUCCESS == retval) {
+ smpi_mpi_irecv(request);
+ }
+ }
+ smpi_mpi_wait(request, &status);
+ xbt_mallocator_release(smpi_global->request_mallocator, request);
+ }
+ xbt_free(requests);
+
+ smpi_bench_begin();
+
+ return retval;
+}
+
+
+
