comparison src/fftw-3.3.8/threads/openmp.c @ 82:d0c2a83c1364

Add FFTW 3.3.8 source, and a Linux build

+/*
+ * Copyright (c) 2003, 2007-14 Matteo Frigo
+ * Copyright (c) 2003, 2007-14 Massachusetts Institute of Technology
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+/* openmp.c: thread spawning via OpenMP  */
+
+#include "threads/threads.h"
+
+#if !defined(_OPENMP)
+#error OpenMP enabled but not using an OpenMP compiler
+#endif
+
+int X(ithreads_init)(void)
+{
+     return 0; /* no error */
+}
+
+/* Distribute a loop from 0 to loopmax-1 over nthreads threads.
+   proc(d) is called to execute a block of iterations from d->min
+   to d->max-1.  d->thr_num indicate the number of the thread
+   that is executing proc (from 0 to nthreads-1), and d->data is
+   the same as the data parameter passed to X(spawn_loop).
+
+   This function returns only after all the threads have completed. */
+void X(spawn_loop)(int loopmax, int nthr, spawn_function proc, void *data)
+{
+     int block_size;
+     spawn_data d;
+     int i;
+
+     A(loopmax >= 0);
+     A(nthr > 0);
+     A(proc);
+
+     if (!loopmax) return;
+
+     /* Choose the block size and number of threads in order to (1)
+        minimize the critical path and (2) use the fewest threads that
+        achieve the same critical path (to minimize overhead).
+        e.g. if loopmax is 5 and nthr is 4, we should use only 3
+        threads with block sizes of 2, 2, and 1. */
+     block_size = (loopmax + nthr - 1) / nthr;
+     nthr = (loopmax + block_size - 1) / block_size;
+
+#pragma omp parallel for private(d)
+     for (i = 0; i < nthr; ++i) {
+	  d.max = (d.min = i * block_size) + block_size;
+	  if (d.max > loopmax)
+	       d.max = loopmax;
+	  d.thr_num = i;
+	  d.data = data;
+	  proc(&d);
+     }
+}
+
+void X(threads_cleanup)(void)
+{
+}
+
+/* FIXME [Matteo Frigo 2015-05-25] What does "thread-safe"
+   mean for openmp? */
+void X(threads_register_planner_hooks)(void)
+{
+}