src/sn-batcher.c: Add program to create batcher mergesort networks.

[sort-networks.git] / src / sn-batcher.c

diff --git a/src/sn-batcher.c b/src/sn-batcher.c
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+++ b/src/sn-batcher.c
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+/**
+ * collectd - src/sn-batcher.c
+ * Copyright (C) 2008,2009  Florian octo Forster
+ *
+ * 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; only version 2 of the License is applicable.
+ *
+ * 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 St, Fifth Floor, Boston, MA  02110-1301 USA
+ *
+ * Authors:
+ *   Florian octo Forster <octo at verplant.org>
+ **/
+
+#ifndef _ISOC99_SOURCE
+# define _ISOC99_SOURCE
+#endif
+#ifndef _POSIX_C_SOURCE
+# define _POSIX_C_SOURCE 200112L
+#endif
+
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "sn_network.h"
+
+static sn_network_t *create_batcher_sort (size_t inputs_num)
+{
+  sn_network_t *n;
+  sn_network_t *n_small;
+
+  if (inputs_num == 2)
+  {
+    sn_stage_t *s;
+    sn_comparator_t c;
+
+    n = sn_network_create (2);
+    if (n == NULL)
+    {
+      fprintf (stderr, "create_batcher_sort: sn_network_create failed.\n");
+      return (NULL);
+    }
+
+    s = sn_stage_create (0);
+    if (s == NULL)
+    {
+      sn_network_destroy (n);
+      fprintf (stderr, "create_batcher_sort: sn_stage_create failed.\n");
+      return (NULL);
+    }
+
+    c.min = 0;
+    c.max = 1;
+
+    sn_stage_comparator_add (s, &c);
+    sn_network_stage_add (n, s);
+
+    return (n);
+  }
+  else if ((inputs_num < 2) || ((inputs_num % 2) != 0))
+  {
+    fprintf (stderr, "create_batcher_sort: Inputs must be a power of two, "
+       "sorry.\n");
+    return (NULL);
+  }
+
+  n_small = create_batcher_sort (inputs_num / 2);
+  if (n_small == NULL)
+    return (NULL);
+
+  n = sn_network_combine_bitonic (n_small, n_small);
+  if (n == NULL)
+  {
+    sn_network_destroy (n_small);
+    fprintf (stderr, "create_batcher_sort: sn_network_combine_bitonic "
+       "failed.\n");
+    return (NULL);
+  }
+
+  sn_network_destroy (n_small);
+  sn_network_compress (n);
+
+  return (n);
+} /* sn_network_t *create_batcher_sort */
+
+int main (int argc, char **argv)
+{
+  sn_network_t *n;
+  size_t inputs_num;
+
+  if (argc != 2)
+  {
+    printf ("Usage: %s <num inputs>\n", argv[0]);
+    return (0);
+  }
+
+  inputs_num = (size_t) atoi (argv[1]);
+  if (inputs_num < 2)
+  {
+    fprintf (stderr, "Invalid number of inputs: %zu\n", inputs_num);
+    return (1);
+  }
+
+  n = create_batcher_sort (inputs_num);
+  if (n == NULL)
+  {
+    printf ("n == NULL!\n");
+    return (1);
+  }
+
+  sn_network_write (n, stdout);
+
+  return (0);
+} /* int main */
+
+/* vim: set shiftwidth=2 softtabstop=2 : */