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| -rw-r--r-- | stdlib/tst-random.c | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/stdlib/tst-random.c b/stdlib/tst-random.c new file mode 100644 index 0000000000..3453d794c4 --- /dev/null +++ b/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); +} |