/*
* Simple random number generator for testing.
- * Copyright © 2022 Nick Bowler
+ * Copyright © 2022-2024 Nick Bowler
*
* 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
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*
- * The RNG implementation is adapted from xoshiro256+ and splitmix64
- * by David Blackman and Sebastiano Vigna, originally distributed under
- * the Creative Commons Zero public domain dedication.
+ * The RNG implementation is adapted from xoshiro256+ by David Blackman
+ * and Sebastiano Vigna, originally distributed under the Creative Commons
+ * Zero public domain dedication.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
-#include <inttypes.h>
#include <errno.h>
#include <limits.h>
-#include <float.h>
-#include <math.h>
+#include <inttypes.h>
-#include "test.h"
+#if !TEST_RNG_NO_EXTERNAL_API
+# include "test.h"
+#endif
-#define B64(x) ((x) & 0xffffffffffffffff)
+#define B64(x) ((x) & 0xffffffffffffffffull)
+#define B32(x) ((x) & 0xffffffffu)
struct test_rng {
unsigned long long state[4];
return ret;
}
-static unsigned long long splitmix64(unsigned long long *state)
+/*
+ * 32-bit random number generator for seed expansion.
+ *
+ * The output filter is from the public domain MurmurHash3 by Austin Appleby.
+ *
+ * The state is incremented by the fractional part of the golden ratio,
+ * i.e., floor( (sqrt(5)-1)/2 * 2**32 )
+ */
+static uint_least32_t splitmix32(uint_least32_t *state)
{
- unsigned long long z;
+ uint_least32_t z;
- z = B64(*state += 0x9e3779b97f4a7c15);
- z = B64((z ^ (z >> 30)) * 0xbf58476d1ce4e5b9);
- z = B64((z ^ (z >> 27)) * 0x94d049bb133111eb);
+ z = B32(*state += 0x9e3779b9);
+ z = B32((z ^ (z >> 16)) * 0x85ebca6b);
+ z = B32((z ^ (z >> 13)) * 0xc2b2ae35);
- return z ^ (z >> 31);
+ return z ^ (z >> 16);
}
-#if HAVE_STRTOULL
-# define STRTOULL strtoull
-#elif HAVE___STRTOULL
-/* HP-UX 11 has __strtoull in <inttypes.h> */
-# define STRTOULL __strtoull
-#else
-/*
- * Just fall back to strtoul -- in the worst case we just lose the ability
- * to set all 64 bits of the seed.
- */
-# define STRTOULL strtoul
-#endif
+static uint_least64_t seed64(uint_least32_t *state)
+{
+ uint_least64_t x;
+
+ x = splitmix32(state);
+ return (x << 32) | splitmix32(state);
+}
+#if !TEST_RNG_NO_EXTERNAL_API
struct test_rng *test_rng_alloc(const char *seed_str)
{
- unsigned long long seed;
+ test_uintmax seed_val;
struct test_rng *rng;
- char *end;
+ uint_least32_t seed;
- errno = 0;
- seed = STRTOULL(seed_str, &end, 0);
- if (*end != 0) {
- fprintf(stderr, "%s: invalid seed\n", seed_str);
- return NULL;
- } else if (errno != 0) {
- fprintf(stderr, "%s: invalid seed: %s\n",
- seed_str, strerror(errno));
+ if (!test_strtoumax(&seed_val, seed_str, 0xffffffff)) {
+ print_error("%s: invalid seed", seed_str);
return NULL;
}
+ seed = seed_val;
rng = malloc_nofail(sizeof *rng);
- rng->state[0] = splitmix64(&seed);
- rng->state[1] = splitmix64(&seed);
- rng->state[2] = splitmix64(&seed);
- rng->state[3] = splitmix64(&seed);
+ rng->state[0] = seed64(&seed);
+ rng->state[1] = seed64(&seed);
+ rng->state[2] = seed64(&seed);
+ rng->state[3] = seed64(&seed);
return rng;
}
free(rng);
}
-#define BITS_PER_FP_DIGIT ( FLT_RADIX < 4 ? 1 \
- : FLT_RADIX < 8 ? 2 \
- : FLT_RADIX < 16 ? 3 \
- : FLT_RADIX < 32 ? 4 \
- : 5 )
-
-double test_rng_uniform(struct test_rng *rng)
-{
- unsigned long long val = xoshiro256p(rng->state);
- int prec = MIN(64, DBL_MANT_DIG*BITS_PER_FP_DIGIT);
-
- return ldexp(val >> (64-prec), -prec);
-}
-
/* Calculate the least power of two greater than val, minus 1. */
static unsigned rng_mask(unsigned val)
{
return val;
}
+#endif