-
#include "surf/random_mgr.h"
#include "xbt/sysdep.h"
#ifdef WIN32
-static double drand48(void)
+
+static unsigned int _seed = 2147483647;
+
+typedef unsigned __int64 uint64_t;
+typedef unsigned int uint32_t;
+
+struct drand48_data
+{
+ unsigned short int __x[3]; /* Current state. */
+ unsigned short int __old_x[3]; /* Old state. */
+ unsigned short int __c; /* Additive const. in congruential formula. */
+ unsigned short int __init; /* Flag for initializing. */
+ unsigned long long int __a; /* Factor in congruential formula. */
+};
+
+static struct drand48_data __libc_drand48_data = {0};
+
+union ieee754_double
+ {
+ double d;
+
+ /* This is the IEEE 754 double-precision format. */
+ struct
+ {
+ /* Together these comprise the mantissa. */
+ unsigned int mantissa1:32;
+ unsigned int mantissa0:20;
+ unsigned int exponent:11;
+ unsigned int negative:1;
+ /* Little endian. */
+ } ieee;
+
+ /* This format makes it easier to see if a NaN is a signalling NaN. */
+ struct
+ {
+ /* Together these comprise the mantissa. */
+ unsigned int mantissa1:32;
+ unsigned int mantissa0:19;
+ unsigned int quiet_nan:1;
+ unsigned int exponent:11;
+ unsigned int negative:1;
+
+ } ieee_nan;
+};
+
+#define IEEE754_DOUBLE_BIAS 0x3ff /* Added to exponent. */
+
+double
+drand48 (void);
+
+int
+_drand48_iterate (unsigned short int xsubi[3], struct drand48_data *buffer);
+
+int
+_erand48_r (unsigned short int xsubi[3], struct drand48_data *buffer, double *result);
+
+
+int
+_erand48_r (unsigned short int xsubi[3], struct drand48_data *buffer, double *result)
+{
+ union ieee754_double temp;
+
+ /* Compute next state. */
+ if (_drand48_iterate(xsubi, buffer) < 0)
+ return -1;
+
+ /* Construct a positive double with the 48 random bits distributed over
+ its fractional part so the resulting FP number is [0.0,1.0). */
+
+ temp.ieee.negative = 0;
+ temp.ieee.exponent = IEEE754_DOUBLE_BIAS;
+ temp.ieee.mantissa0 = (xsubi[2] << 4) | (xsubi[1] >> 12);
+ temp.ieee.mantissa1 = ((xsubi[1] & 0xfff) << 20) | (xsubi[0] << 4);
+
+ /* Please note the lower 4 bits of mantissa1 are always 0. */
+ *result = temp.d - 1.0;
+
+ return 0;
+}
+
+int
+_drand48_iterate (unsigned short int xsubi[3], struct drand48_data *buffer)
+{
+ uint64_t X;
+ uint64_t result;
+
+ /* Initialize buffer, if not yet done. */
+
+ if(buffer->__init == 0)
+ {
+ buffer->__a = 0x5deece66dull;
+ buffer->__c = 0xb;
+ buffer->__init = 1;
+ }
+
+ /* Do the real work. We choose a data type which contains at least
+ 48 bits. Because we compute the modulus it does not care how
+ many bits really are computed. */
+
+ X = (uint64_t) xsubi[2] << 32 | (uint32_t) xsubi[1] << 16 | xsubi[0];
+
+ result = X * buffer->__a + buffer->__c;
+
+
+ xsubi[0] = result & 0xffff;
+ xsubi[1] = (result >> 16) & 0xffff;
+ xsubi[2] = (result >> 32) & 0xffff;
+
+ return 0;
+}
+
+
+double
+_drand48 (void)
+{
+ double result;
+
+ (void) _erand48_r (__libc_drand48_data.__x, &__libc_drand48_data, &result);
+
+ return result;
+ }
+
+void
+_srand(unsigned int seed)
+{
+ _seed = seed;
+}
+
+int
+_rand(void)
{
- return rand()/(double)RAND_MAX;
+ const long a = 16807;
+ const long m = 2147483647;
+ const long q = 127773; /* (m/a) */
+ const long r = 2836; /* (m%a) */
+
+ long lo, k, s;
+
+ s = (long)_seed;
+
+ k = (long)(s/q);
+
+ lo = (s - q * k);
+
+ s = a * lo -r * k;
+
+ if(s <= 0)
+ s += m;
+
+ _seed = (int)(s & RAND_MAX);
+
+ return _seed;
+}
+
+int
+_rand_r(unsigned int* pseed)
+{
+ const long a = 16807;
+ const long m = 2147483647;
+ const long q = 127773; /* (m/a) */
+ const long r = 2836; /* (m%a) */
+
+ long lo, k, s;
+
+ s = (long)*pseed;
+
+ k = (long)(s/q);
+
+ lo = (s - q * k);
+
+ s = a * lo -r * k;
+
+ if(s <= 0)
+ s += m;
+
+ return (int)(s & RAND_MAX);
+
}
+
+
+#define rand_r _rand_r
+#define drand48 _drand48
+
#endif
-static double custom_random(int generator){
+static double custom_random(Generator generator, long int *seed){
switch(generator) {
-
- case DRAND48:return drand48();
- case RAND: return (double)rand()/RAND_MAX;
- default: return drand48();
+
+ case DRAND48:
+ return drand48();
+ case RAND:
+ return (double)rand_r((unsigned int*)seed)/RAND_MAX;
+ default:
+ return drand48();
}
}
/* Generate numbers between min and max with a given mean and standard deviation */
-float random_generate(random_data_t random){
- float x1, x2, w, y;
-
- if (random == NULL) return 0.0f;
+double random_generate(random_data_t random) {
+ double a, b;
+ double alpha, beta, gamma;
+ double U1, U2, V, W, X;
+
+ if (random == NULL) return 0.0f;
+
+ if (random->std == 0)
+ return random->mean * (random->max - random->min) + random->min;
+
+ a = random->mean * ( random->mean * (1 - random->mean) / (random->std*random->std) - 1 );
+ b = (1 - random->mean) * ( random->mean * (1 - random->mean) / (random->std*random->std) - 1 );
+
+ alpha = a + b;
+ if (a <= 1. || b <= 1.)
+ beta = ((1./a)>(1./b))?(1./a):(1./b);
+ else
+ beta = sqrt ((alpha-2.) / (2.*a*b - alpha));
+ gamma = a + 1./beta;
do {
- /* Apply the polar form of the Box-Muller Transform to map the two uniform random numbers to a pair of numbers from a normal distribution.
- It is good for speed because it does not call math functions many times. Another way would be to simply:
- y1 = sqrt( - 2 * log(x1) ) * cos( 2 * pi * x2 )
- */
- do {
- x1 = 2.0 * custom_random(random->generator) - 1.0;
- x2 = 2.0 * custom_random(random->generator) - 1.0;
- w = x1 * x1 + x2 * x2;
- } while ( w >= 1.0 );
+ /* Random generation for the Beta distribution based on
+ * R. C. H. Cheng (1978). Generating beta variates with nonintegral shape parameters. _Communications of the ACM_, *21*, 317-322.
+ * It is good for speed because it does not call math functions many times and respect the 4 given constraints
+ */
+ U1 = custom_random(random->generator,&(random->seed));
+ U2 = custom_random(random->generator,&(random->seed));
- w = sqrt( (-2.0 * log( w ) ) / w );
- y = x1 * w;
+ V = beta * log(U1/(1-U1));
+ W = a * exp(V);
+ } while (alpha * log(alpha/(b + W)) + gamma*V - log(4) < log(U1*U1*U2));
- /* Multiply the Box-Muller value by the standard deviation and add the mean */
- y = y * random->stdDeviation + random->mean;
- } while (!(random->min <= y && y <= random->max));
+ X = W / (b + W);
- return y;
+ return X * (random->max - random->min) + random->min;
}
-random_data_t random_new(int generator, int min, int max, int mean, int stdDeviation){
+random_data_t random_new(Generator generator, long int seed,
+ double min, double max,
+ double mean, double std){
random_data_t random = xbt_new0(s_random_data_t, 1);
+
random->generator = generator;
+ random->seed = seed;
random->min = min;
random->max = max;
- random->mean = mean;
- random->stdDeviation = stdDeviation;
+
+ /* Check user stupidities */
+ if (max < min)
+ THROW2(arg_error,0,"random->max < random->min (%f < %f)",max, min);
+ if (mean < min)
+ THROW2(arg_error,0,"random->mean < random->min (%f < %f)",mean, min);
+ if (mean > max)
+ THROW2(arg_error,0,"random->mean > random->max (%f > %f)",mean, max);
+
+ /* normalize the mean and standard deviation before storing */
+ random->mean = (mean - min) / (max - min);
+ random->std = std / (max - min);
+
+ if (random->mean * (1-random->mean) < random->std*random->std)
+ THROW2(arg_error,0,"Invalid mean and standard deviation (%f and %f)",random->mean, random->std);
+
return random;
}
-
