From 9a16fa090a936f5f920f9c931b9d404adda144e1 Mon Sep 17 00:00:00 2001
From: Achim Gsell <achim.gsell@psi.ch>
Date: Fri, 8 Apr 2016 19:06:15 +0200
Subject: [PATCH] example/H5Block/write_field.c: - slice in Z direction

---
 examples/H5Block/write_field.c | 59 ++++++++++++++++++++++------------
 1 file changed, 38 insertions(+), 21 deletions(-)

diff --git a/examples/H5Block/write_field.c b/examples/H5Block/write_field.c
index 815647e..679cedd 100644
--- a/examples/H5Block/write_field.c
+++ b/examples/H5Block/write_field.c
@@ -10,17 +10,24 @@
 #include "H5hut.h"
 
 // name of output file
-const char* fname = "example_setnparticles.h5";
+const char* fname = "example_write_field.h5";
 
 // H5hut verbosity level
 const h5_int64_t h5_verbosity = H5_VERBOSE_DEFAULT;
 
 // number of particles we are going to write per core
-const ssize_t dim_x = 32;
+const ssize_t dim_x = 8;
 const ssize_t dim_y = 8;
-const ssize_t dim_z = 8;
+const ssize_t dim_z = 32;
 
-#define idx(i, j, k)	(i + j*dim_y + k*dim_x*dim_y)
+
+inline ssize_t idx (
+	ssize_t i, ssize_t i_dim,
+	ssize_t j, ssize_t j_dim,
+	ssize_t k
+	) {
+	return (i + j*i_dim + k*i_dim*j_dim);
+}
 
 int
 main (
@@ -33,41 +40,51 @@ main (
         MPI_Comm comm = MPI_COMM_WORLD;
         int comm_size = 1;
         MPI_Comm_size (comm, &comm_size);
-        int comm_rank = 0;
+	int comm_rank = 0;
         MPI_Comm_rank (comm, &comm_rank);
         H5AbortOnError ();
         H5SetVerbosityLevel (h5_verbosity);
-	H5SetDebugMask (-1);
 
-	// slice field in X direction
-
-	ssize_t n_slices = dim_x / comm_size;
-	ssize_t remaining_slices = dim_x % comm_size;
-	ssize_t i_start = comm_rank * n_slices;
+	// slice field in Z direction
+	ssize_t dim = dim_z;
+	ssize_t n_slices = dim / comm_size;
+	ssize_t remaining_slices = dim % comm_size;
+	ssize_t start;
 	if (comm_rank < remaining_slices) {
 		n_slices++;
-		i_start += comm_rank;
+		start = comm_rank * n_slices;
 	} else {
-		i_start += remaining_slices;
+		start = comm_rank*n_slices + remaining_slices;
 	}
-	ssize_t i_end = i_start + n_slices;
+	ssize_t end = start + n_slices - 1;
 
+	// setting our view
+	ssize_t i_start = 0;
+	ssize_t i_end = dim_x - 1;
+	ssize_t j_start = 0;
+	ssize_t j_end = dim_y - 1;
+	ssize_t k_start = start;
+	ssize_t k_end = end;
+	
 	// create fake data
-        h5_int64_t data[(i_end-i_start+1) * dim_y * dim_z];
-	for (int k = 0; k < dim_z; k++) {
-		for (int j = 0; j < dim_y; j++) {
-			for (int i = i_start; i < i_end; i++) {
-				data[idx(i-i_start,j,k)] = (h5_int64_t)idx(i,j,k);
+	ssize_t i_dim = i_end - i_start + 1;
+	ssize_t j_dim = j_end - j_start + 1;
+        h5_int64_t data[(i_end-i_start+1) * (j_end-j_start+1) * (k_end-k_start+1)];
+	for (int k = k_start; k <= k_end; k++) {
+		for (int j = j_start; j <= j_end; j++) {
+			for (int i = i_start; i <= i_end; i++) {
+				ssize_t _idx = idx (i-i_start, i_dim, j-j_start, j_dim, k-k_start);
+				data[_idx] = (h5_int64_t)idx (i, dim_x, j, dim_y, k);
 			}
 		}
 	}
-	
 
         // open file and create first step
         h5_file_t file = H5OpenFile (fname, H5_O_WRONLY, H5_PROP_DEFAULT);
         H5SetStep (file, 0); 
 
-	H5Block3dSetView (file, i_start, i_end, 0, dim_y-1, 0, dim_z-1);
+	// set view on data for this core
+	H5Block3dSetView (file, i_start, i_end, j_start, j_end, k_start, k_end);
 	
         // write data
         H5Block3dWriteScalarFieldInt64 (file, "data", data);