Defines C++ classes for xbt RNG.

[simgrid.git] / src / xbt / random.cpp

diff --git a/src/xbt/random.cpp b/src/xbt/random.cpp
index 9187dce..dd4b3db 100644 (file)
--- a/src/xbt/random.cpp
+++ b/src/xbt/random.cpp
@@ -6,36 +6,38 @@
 #include "xbt/random.hpp"
 #include "xbt/asserts.h"
 #include <limits>
-#include <random>
+#include <memory>
 
 namespace simgrid {
 namespace xbt {
 namespace random {
-enum xbt_random_implem { XBT_RNG_xbt, XBT_RNG_std };
-static xbt_random_implem rng_implem = XBT_RNG_xbt;
 
-static std::mt19937 mt19937_gen;
-
-void set_implem_xbt()
+int StdRandom::uniform_int(int min, int max)
 {
-  rng_implem = XBT_RNG_xbt;
+  std::uniform_int_distribution<> dist(min, max);
+  return dist(mt19937_gen);
 }
-void set_implem_std()
+
+double StdRandom::uniform_real(double min, double max)
 {
-  rng_implem = XBT_RNG_std;
+  std::uniform_real_distribution<> dist(min, max);
+  return dist(mt19937_gen);
 }
-void set_mersenne_seed(int seed)
+
+double StdRandom::exponential(double lambda)
 {
-  mt19937_gen.seed(seed);
+  std::exponential_distribution<> dist(lambda);
+  return dist(mt19937_gen);
 }
 
-int uniform_int(int min, int max)
+double StdRandom::normal(double mean, double sd)
 {
-  if (rng_implem == XBT_RNG_std) {
-    std::uniform_int_distribution<> dist(min, max);
-    return dist(mt19937_gen);
-  }
+  std::normal_distribution<> dist(mean, sd);
+  return dist(mt19937_gen);
+}
 
+int XbtRandom::uniform_int(int min, int max)
+{
   unsigned long range  = max - min + 1;
   xbt_assert(min <= max,
              "The minimum value for the uniform integer distribution must not be greater than the maximum value");
@@ -47,13 +49,8 @@ int uniform_int(int min, int max)
   return value % range + min;
 }
 
-double uniform_real(double min, double max)
+double XbtRandom::uniform_real(double min, double max)
 {
-  if (rng_implem == XBT_RNG_std) {
-    std::uniform_real_distribution<> dist(min, max);
-    return dist(mt19937_gen);
-  }
-
   // This reuses Boost's uniform real distribution ideas
   constexpr unsigned long divisor = decltype(mt19937_gen)::max() - decltype(mt19937_gen)::min();
   unsigned long numerator;
@@ -63,23 +60,13 @@ double uniform_real(double min, double max)
   return min + (max - min) * numerator / divisor;
 }
 
-double exponential(double lambda)
+double XbtRandom::exponential(double lambda)
 {
-  if (rng_implem == XBT_RNG_std) {
-    std::exponential_distribution<> dist(lambda);
-    return dist(mt19937_gen);
-  }
-
   return -1.0 / lambda * log(uniform_real(0.0, 1.0));
 }
 
-double normal(double mean, double sd)
+double XbtRandom::normal(double mean, double sd)
 {
-  if (rng_implem == XBT_RNG_std) {
-    std::normal_distribution<> dist(mean, sd);
-    return dist(mt19937_gen);
-  }
-
   double u1;
   do {
     u1 = uniform_real(0.0, 1.0);
@@ -89,6 +76,42 @@ double normal(double mean, double sd)
   return z0 * sd + mean;
 }
 
+static std::unique_ptr<Random> default_random(new XbtRandom);
+
+void set_implem_xbt()
+{
+  default_random.reset(new XbtRandom);
+}
+void set_implem_std()
+{
+  default_random.reset(new StdRandom);
+}
+
+void set_mersenne_seed(int seed)
+{
+  default_random->set_seed(seed);
+}
+
+int uniform_int(int min, int max)
+{
+  return default_random->uniform_int(min, max);
+}
+
+double uniform_real(double min, double max)
+{
+  return default_random->uniform_real(min, max);
+}
+
+double exponential(double lambda)
+{
+  return default_random->exponential(lambda);
+}
+
+double normal(double mean, double sd)
+{
+  return default_random->normal(mean, sd);
+}
+
 } // namespace random
 } // namespace xbt
 } // namespace simgrid