X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=src%2Fsn_network.c;h=1b3dd3630515aaa92adbdd18eeed51cd2a2fb427;hb=2b64b183834075911f9e53a6f0132d116bf45a76;hp=0705a91d543a1a5ed3fcd8b1f522b1109a08dea6;hpb=bc19ee0ad538c81aee72110e77e24bf0d5540ae5;p=sort-networks.git

diff --git a/src/sn_network.c b/src/sn_network.c
index 0705a91..1b3dd36 100644
--- a/src/sn_network.c
+++ b/src/sn_network.c
@@ -1,5 +1,5 @@
 /**
- * collectd - src/sn_network.c
+ * libsortnetwork - src/sn_network.c
  * Copyright (C) 2008-2010  Florian octo Forster
  *
  * This program is free software; you can redistribute it and/or modify it
@@ -38,6 +38,7 @@
 #include <strings.h>
 #include <ctype.h>
 #include <assert.h>
+#include <errno.h>
 
 #include "sn_network.h"
 #include "sn_random.h"
@@ -134,10 +135,85 @@ sn_network_t *sn_network_create_odd_even_mergesort (int inputs_num) /* {{{ */
   }
 } /* }}} sn_network_t *sn_network_create_odd_even_mergesort */
 
+static int sn_network_create_pairwise_internal (sn_network_t *n, /* {{{ */
+    int *inputs, int inputs_num)
+{
+  int i;
+  int inputs_copy[inputs_num];
+  int m;
+
+  for (i = 1; i < inputs_num; i += 2)
+  {
+    sn_comparator_t *c = sn_comparator_create (inputs[i-1], inputs[i]);
+    sn_network_comparator_add (n, c);
+    sn_comparator_destroy (c);
+  }
+
+  if (inputs_num <= 2)
+    return (0);
+
+  /* Sort "pairs" recursively. Like with odd-even mergesort, odd and even lines
+   * are handled recursively and later reunited. */
+  for (i = 0; i < inputs_num; i += 2)
+    inputs_copy[(int) (i / 2)] = inputs[i];
+  /* Recursive call #1 with first set of lines */
+  sn_network_create_pairwise_internal (n, inputs_copy,
+      (int) ((inputs_num + 1) / 2));
+
+  for (i = 1; i < inputs_num; i += 2)
+    inputs_copy[(int) (i / 2)] = inputs[i];
+  /* Recursive call #2 with second set of lines */
+  sn_network_create_pairwise_internal (n, inputs_copy,
+      (int) (inputs_num/ 2));
+
+  /* m is the "amplitude" of the sorted pairs. This is a bit tricky to read due
+   * to different indices being used in the paper, unfortunately. */
+  m = inputs_num / 2;
+  while (m > 1)
+  {
+    for (i = 1; (i + (m - 1)) < inputs_num; i += 2)
+    {
+      int left = i;
+      int right = i + (m - 1);
+      sn_comparator_t *c;
+
+      assert (left < right);
+      c = sn_comparator_create (inputs[left], inputs[right]);
+      sn_network_comparator_add (n, c);
+      sn_comparator_destroy (c);
+    }
+
+    m = m / 2;
+  } /* while (m > 1) */
+
+  return (0);
+} /* }}} int sn_network_create_pairwise_internal */
+
+sn_network_t *sn_network_create_pairwise (int inputs_num) /* {{{ */
+{
+  sn_network_t *n = sn_network_create (inputs_num);
+  int inputs[inputs_num];
+  int i;
+
+  if (n == NULL)
+    return (NULL);
+
+  for (i = 0; i < inputs_num; i++)
+    inputs[i] = i;
+  
+  sn_network_create_pairwise_internal (n, inputs, inputs_num);
+  sn_network_compress (n);
+
+  return (n);
+} /* }}} sn_network_t *sn_network_create_pairwise */
+
 int sn_network_stage_add (sn_network_t *n, sn_stage_t *s) /* {{{ */
 {
   sn_stage_t **temp;
 
+  if ((n == NULL) || (s == NULL))
+    return (EINVAL);
+
   temp = (sn_stage_t **) realloc (n->stages, (n->stages_num + 1)
       * sizeof (sn_stage_t *));
   if (temp == NULL)
@@ -156,7 +232,8 @@ int sn_network_stage_remove (sn_network_t *n, int s_num) /* {{{ */
   int nmemb = n->stages_num - (s_num + 1);
   sn_stage_t **temp;
 
-  assert (s_num < n->stages_num);
+  if ((n == NULL) || (s_num >= n->stages_num))
+    return (EINVAL);
 
   sn_stage_destroy (n->stages[s_num]);
   n->stages[s_num] = NULL;
@@ -225,7 +302,7 @@ int sn_network_comparator_add (sn_network_t *n, /* {{{ */
   sn_stage_t *s;
 
   if ((n == NULL) || (c == NULL))
-    return (-1);
+    return (EINVAL);
 
   if (n->stages_num > 0)
   {
@@ -274,6 +351,9 @@ int sn_network_invert (sn_network_t *n) /* {{{ */
 {
   int i;
 
+  if (n == NULL)
+    return (EINVAL);
+
   for (i = 0; i < n->stages_num; i++)
     sn_stage_invert (n->stages[i]);
 
@@ -284,6 +364,12 @@ int sn_network_shift (sn_network_t *n, int sw) /* {{{ */
 {
   int i;
 
+  if ((n == NULL) || (sw < 0))
+    return (EINVAL);
+
+  if (sw == 0)
+    return (0);
+
   for (i = 0; i < n->stages_num; i++)
     sn_stage_shift (n->stages[i], sw, SN_NETWORK_INPUT_NUM (n));
 
@@ -658,11 +744,11 @@ static sn_network_t *sn_network_combine_bitonic_shift (sn_network_t *n0, /* {{{
   return (n);
 } /* }}} sn_network_t *sn_network_combine_bitonic_shift */
 
-sn_network_t *sn_network_combine_bitonic (sn_network_t *n0, /* {{{ */
+sn_network_t *sn_network_combine_bitonic_merge (sn_network_t *n0, /* {{{ */
     sn_network_t *n1)
 {
   return (sn_network_combine_bitonic_shift (n0, n1, /* do_shift = */ 0));
-} /* }}} sn_network_t *sn_network_combine_bitonic */
+} /* }}} sn_network_t *sn_network_combine_bitonic_merge */
 
 sn_network_t *sn_network_combine_odd_even_merge (sn_network_t *n0, /* {{{ */
     sn_network_t *n1)
@@ -697,27 +783,12 @@ sn_network_t *sn_network_combine_odd_even_merge (sn_network_t *n0, /* {{{ */
 
   sn_network_compress (n);
   return (n);
-} /* }}} sn_network_t *sn_network_combine */
+} /* }}} sn_network_t *sn_network_combine_odd_even_merge */
 
 sn_network_t *sn_network_combine (sn_network_t *n0, /* {{{ */
-    sn_network_t *n1, int is_power_of_two)
+    sn_network_t *n1)
 {
-  sn_network_t *n;
-
-  if ((is_power_of_two != 0) && (sn_bounded_random (0, 9) == 0))
-  {
-    DPRINTF ("sn_network_combine: Using the bitonic merger.\n");
-    n = sn_network_combine_bitonic_shift (n0, n1, /* do_shift = */ 1);
-  }
-  else
-  {
-    DPRINTF ("sn_network_combine: Using the odd-even merger.\n");
-    n = sn_network_combine_odd_even_merge (n0, n1);
-  }
-
-  sn_network_compress (n);
-
-  return (n);
+  return (sn_network_combine_odd_even_merge (n0, n1));
 } /* }}} sn_network_t *sn_network_combine */
 
 int sn_network_sort (sn_network_t *n, int *values) /* {{{ */