ENH: Random numbers - added re-entrant random interface

src/OSspecific/POSIX/POSIX.C

@@ -59,7 +59,6 @@ Description
 #include <link.h>
 
 #include <netinet/in.h>
-
 #ifdef USE_RANDOM
     #include <climits>
     #if INT_MAX    != 2147483647
@@ -1430,6 +1429,15 @@ Foam::fileNameList Foam::dlLoaded()
     return libs;
 }
 
+Foam::label Foam::osRandomBufferSize()
+{
+    #ifdef USE_RANDOM
+    return sizeof(random_data);
+    #else
+    return sizeof(drand48_data);
+    #endif
+}
+
 
 void Foam::osRandomSeed(const label seed)
 {
@@ -1461,4 +1469,42 @@ Foam::scalar Foam::osRandomDouble()
 }
 
 
+void Foam::osRandomSeed(const label seed, List<char>& buffer)
+{
+    #ifdef USE_RANDOM
+    srandom_r((unsigned int)seed, reinterpret_cast<random_data*>(buffer.begin()));
+    #else
+    srand48_r(seed, reinterpret_cast<drand48_data*>(buffer.begin()));
+    #endif
+}
+
+
+Foam::label Foam::osRandomInteger(List<char>& buffer)
+{
+    #ifdef USE_RANDOM
+    int32_t result;
+    random_r(reinterpret_cast<random_data*>(buffer.begin()), &result);
+    return result;
+    #else
+    long result;
+    lrand48_r(reinterpret_cast<drand48_data*>(buffer.begin()), &result);
+    return result;
+    #endif
+}
+
+
+Foam::scalar Foam::osRandomDouble(List<char>& buffer)
+{
+    #ifdef USE_RANDOM
+    int32_t result;
+    random_r(reinterpret_cast<random_data*>(buffer.begin()), &result);
+    return (scalar)result/INT_MAX;
+    #else
+    double result;
+    drand48_r(reinterpret_cast<drand48_data*>(buffer.begin()), &result);
+    return result;
+    #endif
+}
+
+
 // ************************************************************************* //

src/OpenFOAM/include/OSspecific.H

@@ -245,6 +245,18 @@ label osRandomInteger();
 //- Return random double precision (uniform distribution between 0 and 1)
 scalar osRandomDouble();
 
+//- Return the size of the buffer for re-entrant random number generator
+label osRandomBufferSize();
+
+//- Seed random number generator.
+void osRandomSeed(const label seed, List<char>& buffer);
+
+//- Return random integer (uniform distribution between 0 and 2^31)
+label osRandomInteger(List<char>& buffer);
+
+//- Return random double precision (uniform distribution between 0 and 1)
+scalar osRandomDouble(List<char>& buffer);
+
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //