examples/H5Part/read_strided{.c,f.f90}

- compute and set a canonical view

examples/H5Part/read_strided.c

@@ -13,8 +13,8 @@
 const char* fname = "example_strided.h5";
 
 // H5hut verbosity level
-//const h5_int64_t h5_verbosity = H5_VERBOSE_DEFAULT;
-const h5_int64_t h5_verbosity = H5_DEBUG_ALL;
+const h5_int64_t h5_verbosity = H5_VERBOSE_DEFAULT;
+//const h5_int64_t h5_verbosity = H5_DEBUG_ALL;
 
 int
 main (
@@ -35,11 +35,18 @@ main (
         h5_file_t file = H5OpenFile (fname, H5_O_RDONLY, H5_PROP_DEFAULT);
         H5SetStep (file, 0);
 
-        // Get number of particles in datasets
-        h5_int64_t num_particles = H5PartGetNumParticles (file);
+        // compute number of particles this process has to read
+        h5_ssize_t num_particles_total = H5PartGetNumParticles (file);
+        h5_ssize_t num_particles = num_particles_total / comm_size;
+        if (comm_rank+1 == comm_size)
+                num_particles += num_particles_total % comm_size;
 
+	printf ("[proc %d]: particles in view: %lld\n", comm_rank, (long long)num_particles);
+	printf ("[proc %d]: total number of particles: %lld\n",
+		comm_rank, (long long unsigned)num_particles_total);
+	
         // set number of particles and memory stride
-        H5PartSetNumParticlesStrided (file, 98, 6);
+        H5PartSetNumParticlesStrided (file, num_particles, 6);
 
         // read data
         h5_float64_t* data = calloc (6*num_particles, sizeof (*data));
@@ -51,7 +58,7 @@ main (
         H5PartReadDataFloat64 (file, "pz", data+5);
 
 	// print dataset "x"
-        for (int i = 0; i < num_particles*6-6; i+=6) {
+        for (int i = 0; i < num_particles*6; i+=6) {
                 printf ("[proc %d]: local index = %d, value = %6.3f\n",
                         comm_rank, i, data[i]);
         }

examples/H5Part/read_stridedf.f90

@@ -20,7 +20,7 @@ program read_stridedf
   
   integer   :: comm, comm_size, comm_rank, mpi_ierror
   integer*8 :: file, h5_ierror
-  integer*8 :: num_particles
+  integer*8 :: num_particles, num_particles_total
   real*8, allocatable :: data(:)
   integer*8 :: i, start
   
@@ -36,10 +36,17 @@ program read_stridedf
   file = h5_openfile (fname, H5_O_RDONLY, H5_PROP_DEFAULT)
   h5_ierror = h5_setstep(file, 1_8)
 
-  ! Get number of particles in datasets
-  num_particles = h5pt_getnpoints (file)
-    
-  ! set number of particles and memory stride
+  ! compute number of particles this process has to read
+  num_particles_total = h5pt_getnpoints (file)
+  num_particles = num_particles_total / comm_size
+  if (comm_rank+1 == comm_size) then
+     num_particles = num_particles + mod (num_particles_total, comm_size)
+  end if
+
+  write (*, "('Total number of particles: ', i8)") num_particles_total
+  write (*, "('Number of particles on this core: ', i8)") num_particles
+
+  ! set number of particeles and memory stride
   h5_ierror = h5pt_setnpoints_strided (file, num_particles, 6_8)
 
   ! read data