Tests for random function family.

stdlib/tst-random.c

@@ -0,0 +1,119 @@
+/* Test program for random(), srandom(), initstate(), setstate()
+   Written by Michael J. Fischer, August 21, 2000
+   Placed in the public domain.  */
+
+/* This program primarily tests the correct functioning of srandom()
+   and setstate().  The strategy is generate and store a set of random
+   sequences, each with a specified starting seed.  Then each sequence
+   is regenerated twice and checked against the stored values.
+
+   First they are regenerated one sequence at a time, using srandom()
+   to set the initial state.  A discrepency here would suggest that
+   srandom() was failing to completely initialize the random number
+   generator.
+
+   Second the sequences are regenerated in an interleaved order.
+   A state vector is created for each sequence using initstate().
+   setstate() is used to switch from sequence to sequence during
+   the interleaved generation.  A discrepency here would suggest
+   a problem with either initstate() failing to initialize the
+   random number generator properly, or the failure of setstate()
+   to correctly save and restore state information.  Also, each
+   time setstate() is called, the returned value is checked for
+   correctness (since we know what it should be).
+
+   Note:  We use default state vector for sequence 0 and our own
+   state vectors for the remaining sequences.  This is to give a check
+   that the value returned by initstate() is valid and can indeed be
+   used in the future.  */
+
+/* Strategy:
+   1.  Use srandom() followed by calls on random to generate a set of
+       sequences of values.
+   2.  Regenerate and check the sequences.
+   3.  Use initstate() to create new states.
+   4.  Regenerate the sequences in an interleaved manner and check.
+*/
+
+#include <stdlib.h>
+#include <stdio.h>
+
+const int degree = 128;		/* random number generator degree (should
+				   be one of 8, 16, 32, 64, 128, 256) */
+const int nseq = 3;		/* number of test sequences */
+const int nrnd = 50;		/* length of each test sequence */
+const unsigned int seed[3] = { 0x12344321U, 0xEE11DD22U, 0xFEDCBA98 };
+
+void fail (const char *msg, int s, int i);
+
+int
+main (void)
+{
+  long int rnd[nseq][nrnd];	/* pseudorandom numbers */
+  char* state[nseq];		/* state for PRNG */
+  char* oldstate[nseq];		/* old PRNG state */
+  int s;			/* sequence index */
+  int i;			/* element index */
+
+  printf ("Begining random package test using %d sequences of length %d.\n",
+	  nseq, nrnd);
+
+  /* 1. Generate and store the sequences.  */
+  printf ("Generating random sequences.\n");
+  for (s = 0; s < nseq; ++s)
+    {
+      srandom ( seed[s] );
+      for (i = 0; i < nrnd; ++i)
+	rnd[s][i] = random ();
+    }
+
+  /* 2. Regenerate and check.  */
+  printf ("Regenerating and checking sequences.\n");
+  for (s = 0; s < nseq; ++s)
+    {
+      srandom (seed[s]);
+      for (i = 0; i < nrnd; ++i)
+	if (rnd[s][i] != random ())
+	  fail ("first regenerate test", s, i);
+    }
+
+  /* 3. Create state vector, one for each sequence.
+	First state is random's internal state; others are malloced.  */
+  printf ("Creating and checking state vector for each sequence.\n");
+  srandom (seed[0]);			/* reseed with first seed */
+  for (s = 1; s < nseq; ++s)
+    {
+      state[s] = (char*) malloc (degree);
+      oldstate[s] = initstate (seed[s], state[s], degree);
+    }
+  state[0] = oldstate[1];
+
+  /* Check returned values.  */
+  for (s = 1; s < nseq - 1; ++s)
+    if (state[s] != oldstate[s + 1])
+      fail ("bad initstate() return value", s, i);
+
+  /* 4. Regenerate sequences interleaved and check.  */
+  printf ("Regenerating and checking sequences in interleaved order.\n");
+  for (i = 0; i < nrnd; ++i)
+    {
+      for (s = 0; s < nseq; ++s)
+	{
+	  char *oldstate = (char *) setstate (state[s]);
+	  if (oldstate != state[(s + nseq - 1) % nseq])
+	    fail ("bad setstate() return value", i, s);
+	  if (rnd[s][i] != random ())
+	    fail ("bad value generated in interleave test", s, i);
+	}
+    }
+  printf ("All tests passed!\n");
+  return 0;
+}
+
+void
+fail (const char *msg, int s, int i)
+{
+  printf ("\nTest FAILED: ");
+  printf ("%s (seq %d, pos %d).\n", msg, s, i);
+  exit (1);
+}