Add `fmpi_halo_exchange_1d()`

include/fmpi_domain.h

@@ -65,6 +65,12 @@ void fmpi_domain_set_inner(
     const struct fmpi_ctx * ctx, const struct fmpi_domain * domain,
     const void * data
 );
+/*------------------------------------------------------------------------------
+    fmpi_halo_exchange_1d()
+------------------------------------------------------------------------------*/
+int fmpi_halo_exchange_1d(
+    const struct fmpi_ctx * ctx, const struct fmpi_domain * domain
+);
 /*==============================================================================
     GUARD
 ==============================================================================*/

src/fmpi_domain.c

@@ -89,6 +89,40 @@ void fmpi_domain_set_inner(
     assert(data != NULL);
     memcpy(domain->inner.raw, data, domain->inner.size);
 }
+/*------------------------------------------------------------------------------
+    fmpi_halo_exchange_1d()
+------------------------------------------------------------------------------*/
+int fmpi_halo_exchange_1d(
+    const struct fmpi_ctx * const ctx, const struct fmpi_domain * const domain
+){
+    assert(ctx != NULL);
+    assert(domain != NULL);
+
+    const size_t idx_1 = domain->halo.type.size;
+    const size_t idx_nm2 = (domain->halo.cnt-2) * domain->halo.type.size;
+    const size_t idx_nm1 = idx_nm2 + idx_1;
+
+          void * const buf_0   = domain->halo.raw;
+    const void * const buf_1   = (char *)buf_0 + idx_1;
+    const void * const buf_nm2 = (char *)buf_0 + idx_nm2;
+          void * const buf_nm1 = (char *)buf_0 + idx_nm1;
+
+    const int rank = ctx->mpi->rank;
+    const int left = (rank != 0) ? (rank - 1) : MPI_PROC_NULL;
+    const int right = (rank != (ctx->mpi->size-1)) ? (rank + 1) : MPI_PROC_NULL;
+    MPI_Datatype type = fmpi_mpi_type(domain->halo.type.base);
+    MPI_Sendrecv(
+        buf_nm2, 1, type, right, 0,
+        buf_0  , 1, type, left , 0,
+        ctx->mpi->world, MPI_STATUS_IGNORE
+    );
+    MPI_Sendrecv(
+        buf_1  , 1, type, left , 1,
+        buf_nm1, 1, type, right, 1,
+        ctx->mpi->world, MPI_STATUS_IGNORE
+    );
+    return FMPI_SUCCESS;
+}
 /*==============================================================================
     PRIVATE FUNCTION DEFINITION
 ==============================================================================*/

src/fmpi_task.c

@@ -128,36 +128,7 @@ int fmpi_task_run_sync(
     }
     if(task->stencil.type != FMPI_STENCIL_NONE) {
         fmpi_domain_set_inner(ctx, &task->domains[0], task->args.out.raw);
-
-        const int rank = ctx->mpi->rank;
-        size_t type_size = task->domains[0].inner.type.size;
-        
-        const size_t idx_1 = type_size;
-        const size_t idx_nm2 = (task->domains[0].halo.cnt-2) * type_size;
-        const size_t idx_nm1 = idx_nm2 + idx_1;
-
-              void * const buf_0   = task->domains[0].halo.raw;
-        const void * const buf_1   = (char *)buf_0 + idx_1;
-        const void * const buf_nm2 = (char *)buf_0 + idx_nm2;
-              void * const buf_nm1 = (char *)buf_0 + idx_nm1;
-
-        MPI_Datatype type = fmpi_mpi_type(task->domains[0].halo.type.base);
-        if((rank % 2) == 0) {
-            int left = (rank != 0) ? (rank - 1) : MPI_PROC_NULL;
-            int right = rank + 1;
-            MPI_Send(buf_nm2, 1, type, right, 0, ctx->mpi->world);
-            MPI_Recv(buf_0  , 1, type, left,  1, ctx->mpi->world, MPI_STATUS_IGNORE);
-            MPI_Send(buf_1  , 1, type, left,  2, ctx->mpi->world);
-            MPI_Recv(buf_nm1, 1, type, right, 3, ctx->mpi->world, MPI_STATUS_IGNORE);
-
-        } else {
-            int left = rank - 1;
-            int right = (rank != (ctx->mpi->size-1)) ? (rank + 1) : MPI_PROC_NULL;
-            MPI_Recv(buf_0  , 1, type, left,  0, ctx->mpi->world, MPI_STATUS_IGNORE);
-            MPI_Send(buf_nm2, 1, type, right, 1, ctx->mpi->world);
-            MPI_Recv(buf_nm1, 1, type, right, 2, ctx->mpi->world, MPI_STATUS_IGNORE);
-            MPI_Send(buf_1  , 1, type, left,  3, ctx->mpi->world);
-        }
+        fmpi_halo_exchange_1d(ctx, &task->domains[0]);
         const int err = fmpi_futhark_free_data_sync(
             ctx->fut, task->args.in[0].gpu, task->domains[0].halo.type.base,
             task->domains[0].halo.dim_cnt