move MT19937 random generator to ddsrt

Signed-off-by: Erik Boasson <eb@ilities.com>

src/ddsrt/tests/CMakeLists.txt

@@ -22,6 +22,7 @@ set(sources
     "thread_cleanup.c"
     "string.c"
     "log.c"
+    "random.c"
     "strlcpy.c"
     "socket.c"
     "select.c")

src/ddsrt/tests/random.c

@@ -0,0 +1,92 @@
+/*
+ * Copyright(c) 2006 to 2018 ADLINK Technology Limited and others
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0, or the Eclipse Distribution License
+ * v. 1.0 which is available at
+ * http://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
+ */
+#include <assert.h>
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "CUnit/Test.h"
+#include "dds/ddsrt/random.h"
+
+#define N_PRNG 4
+#define N_DATA 10
+
+CU_Test(ddsrt_random, mt19937)
+{
+  static const uint32_t refdata[N_DATA] = {
+    3499211612u, 581869302u, 3890346734u, 3586334585u, 545404204u,
+    4161255391u, 3922919429u, 949333985u, 2715962298u, 1323567403u
+  };
+  ddsrt_prng_t prng;
+  ddsrt_prng_init_simple (&prng, 5489U);
+  for (size_t i = 0; i < N_DATA; i++)
+  {
+    uint32_t x = ddsrt_prng_random (&prng);
+    CU_ASSERT_EQUAL_FATAL(x, refdata[i]);
+  }
+}
+
+CU_Test(ddsrt_random, makeseed)
+{
+  ddsrt_prng_seed_t seeds[N_PRNG];
+
+  /* Until proven otherwise, assume all platforms have a good way of getting multiple seeds */
+  memset (seeds, 0, sizeof (seeds));
+  for (size_t i = 0; i < N_PRNG; i++)
+  {
+    bool ok = ddsrt_prng_makeseed (&seeds[i]);
+    CU_ASSERT_FATAL(ok);
+  }
+
+  /* Any pair the same is possible, but the likelihood should be so small that it is worth accepting
+     an intermittently failing test */
+  for (size_t i = 0; i < N_PRNG; i++)
+  {
+    for (size_t j = i + 1; j < N_PRNG; j++)
+      CU_ASSERT_FATAL (memcmp (&seeds[i], &seeds[j], sizeof (seeds[i])) != 0);
+  }
+
+  /* A short random sequence generated from each of the different seeds should be unique -- again,
+     there is no guarantee but only an overwhelming likelihood */
+  ddsrt_prng_t prngs[N_PRNG];
+  uint32_t data[N_PRNG][N_DATA];
+  memset (data, 0, sizeof (data));
+  for (size_t i = 0; i < N_PRNG; i++)
+  {
+    ddsrt_prng_init (&prngs[i], &seeds[i]);
+    for (size_t j = 0; j < N_DATA; j++)
+      data[i][j] = ddsrt_prng_random (&prngs[i]);
+  }
+  for (size_t i = 0; i < N_PRNG; i++)
+  {
+    for (size_t j = i + 1; j < N_PRNG; j++)
+      CU_ASSERT_FATAL (memcmp (&data[i], &data[j], sizeof (data[i])) != 0);
+  }
+}
+
+CU_Test(ddsrt_random, default_random)
+{
+#define N_BINS 128
+#define N_PER_BIN 100
+  uint32_t bins[N_BINS];
+  memset (bins, 0, sizeof (bins));
+  for (size_t i = 0; i < N_PER_BIN * N_BINS; i++)
+  {
+    uint32_t x = ddsrt_random ();
+    bins[x % N_BINS]++;
+  }
+  double chisq = 0.0;
+  for (size_t i = 0; i < N_BINS; i++)
+    chisq += ((bins[i] - N_PER_BIN) * (bins[i] - N_PER_BIN)) / (double) N_PER_BIN;
+  /* Solve[CDF[ChiSquareDistribution[127], x] == 999/1000] */
+  CU_ASSERT (chisq < 181.993);
+}