namespace simgrid {
namespace xbt {
namespace random {
-std::mt19937 mt19937_gen;
-xbt_random_method current_rng = XBT_RNG_xbt;
+enum xbt_random_implem { XBT_RNG_xbt, XBT_RNG_std };
+static xbt_random_implem rng_implem = XBT_RNG_xbt;
-void use_xbt()
+static std::mt19937 mt19937_gen;
+
+void set_implem_xbt()
+{
+ rng_implem = XBT_RNG_xbt;
+}
+void set_implem_std()
{
- current_rng = XBT_RNG_xbt;
+ rng_implem = XBT_RNG_std;
}
-void use_std()
+void set_mersenne_seed(int seed)
{
- current_rng = XBT_RNG_std;
+ mt19937_gen.seed(seed);
}
int uniform_int(int min, int max)
{
- switch (current_rng) {
- case XBT_RNG_xbt:
- return xbt_uniform_int(min, max);
- case XBT_RNG_std: {
- std::uniform_int_distribution<> dist(min, max);
- return dist(mt19937_gen);
+ if (rng_implem == XBT_RNG_std) {
+ std::uniform_int_distribution<> dist(min, max);
+ return dist(mt19937_gen);
}
- default:
- xbt_assert(false, "The uniform integer distribution is not yet supported for the current RNG.");
- }
-}
-int xbt_uniform_int(int min, int max)
-{
- unsigned long gmin = mt19937_gen.min();
- unsigned long gmax = mt19937_gen.max();
- unsigned long grange = gmax - gmin + 1;
unsigned long range = max - min + 1;
+ unsigned long value = mt19937_gen();
+ xbt_assert(range > 0, "Overflow in the uniform integer distribution, please use a smaller range.");
xbt_assert(
min <= max,
"The maximum value for the uniform integer distribution must be greater than or equal to the minimum value");
- xbt_assert(range <= grange, "The current implementation of the uniform integer distribution does not allow range to "
- "be higher than mt19937's range");
- unsigned long mult = grange / range;
- unsigned long maxallowed = gmin + (mult + 1) * range - 1;
- while (true) {
- unsigned long value = mt19937_gen();
- if (value > maxallowed) {
- } else {
- return value % range + min;
- }
- }
+ return value % range + min;
}
double uniform_real(double min, double max)
{
- switch (current_rng) {
- case XBT_RNG_xbt:
- return xbt_uniform_real(min, max);
- case XBT_RNG_std: {
- std::uniform_real_distribution<> dist(min, max);
- return dist(mt19937_gen);
+ if (rng_implem == XBT_RNG_std) {
+ std::uniform_real_distribution<> dist(min, max);
+ return dist(mt19937_gen);
}
- default:
- xbt_assert(false, "The uniform real distribution is not yet supported for the current RNG.");
- }
-}
-double xbt_uniform_real(double min, double max)
-{
// This reuses Boost's uniform real distribution ideas
unsigned long numerator = mt19937_gen() - mt19937_gen.min();
unsigned long divisor = mt19937_gen.max() - mt19937_gen.min();
double exponential(double lambda)
{
- switch (current_rng) {
- case XBT_RNG_xbt:
- return xbt_exponential(lambda);
- case XBT_RNG_std: {
- std::exponential_distribution<> dist(lambda);
- return dist(mt19937_gen);
+ if (rng_implem == XBT_RNG_std) {
+ std::exponential_distribution<> dist(lambda);
+ return dist(mt19937_gen);
}
- default:
- xbt_assert(false, "The exponential distribution is not yet supported for the current RNG.");
- }
-}
-double xbt_exponential(double lambda)
-{
return -1 / lambda * log(uniform_real(0, 1));
}
double normal(double mean, double sd)
{
- switch (current_rng) {
- case XBT_RNG_xbt:
- return xbt_normal(mean, sd);
- case XBT_RNG_std: {
- std::normal_distribution<> dist(mean, sd);
- return dist(mt19937_gen);
- }
- default:
- xbt_assert(false, "The normal distribution is not yet supported for the curent RNG.");
+ if (rng_implem == XBT_RNG_std) {
+ std::normal_distribution<> dist(mean, sd);
+ return dist(mt19937_gen);
}
-}
-double xbt_normal(double mean, double sd)
-{
double u1 = 0;
while (u1 < std::numeric_limits<double>::min()) {
u1 = uniform_real(0, 1);
return z0 * sd + mean;
}
-void set_mersenne_seed(int seed)
-{
- mt19937_gen.seed(seed);
-}
-
} // namespace random
} // namespace xbt
} // namespace simgrid