1 files changed, 143 insertions, 0 deletions
diff --git a/gsl-1.9/rng/rand48.c b/gsl-1.9/rng/rand48.c
new file mode 100644
index 0000000..f01a351
--- /dev/null
+++ b/gsl-1.9/rng/rand48.c
@@ -0,0 +1,143 @@
+/* rng/rand48.c
+ * 
+ * Copyright (C) 1996, 1997, 1998, 1999, 2000 James Theiler, Brian Gough
+ * 
+ * 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
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include <config.h>
+#include <math.h>
+#include <stdlib.h>
+#include <gsl/gsl_sys.h>
+#include <gsl/gsl_rng.h>
+
+/* This is the Unix rand48() generator. The generator returns the
+   upper 32 bits from each term of the sequence,
+
+   x_{n+1} = (a x_n + c) mod m 
+
+   using 48-bit unsigned arithmetic, with a = 0x5DEECE66D , c = 0xB
+   and m = 2^48. The seed specifies the upper 32 bits of the initial
+   value, x_1, with the lower 16 bits set to 0x330E.
+
+   The theoretical value of x_{10001} is 244131582646046.
+
+   The period of this generator is ? FIXME (probably around 2^48). */
+
+static inline void rand48_advance (void *vstate);
+static unsigned long int rand48_get (void *vstate);
+static double rand48_get_double (void *vstate);
+static void rand48_set (void *state, unsigned long int s);
+
+static const unsigned short int a0 = 0xE66D ;
+static const unsigned short int a1 = 0xDEEC ;
+static const unsigned short int a2 = 0x0005 ;
+
+static const unsigned short int c0 = 0x000B ;
+
+typedef struct
+  {
+    unsigned short int x0, x1, x2;
+  }
+rand48_state_t;
+
+static inline void
+rand48_advance (void *vstate)
+{
+  rand48_state_t *state = (rand48_state_t *) vstate;
+
+  /* work with unsigned long ints throughout to get correct integer
+     promotions of any unsigned short ints */
+
+  const unsigned long int x0 = (unsigned long int) state->x0 ;
+  const unsigned long int x1 = (unsigned long int) state->x1 ;
+  const unsigned long int x2 = (unsigned long int) state->x2 ;
+
+  unsigned long int a ;
+  
+  a = a0 * x0 + c0 ;
+  state->x0 = (a & 0xFFFF) ;
+ 
+  a >>= 16 ;
+
+  /* although the next line may overflow we only need the top 16 bits
+     in the following stage, so it does not matter */
+
+  a += a0 * x1 + a1 * x0 ; 
+  state->x1 = (a & 0xFFFF) ;
+
+  a >>= 16 ;
+  a += a0 * x2 + a1 * x1 + a2 * x0 ;
+  state->x2 = (a & 0xFFFF) ;
+}
+
+static unsigned long int 
+rand48_get (void *vstate)
+{
+  unsigned long int x1, x2;
+
+  rand48_state_t *state = (rand48_state_t *) vstate;
+  rand48_advance (state) ;
+
+  x2 = (unsigned long int) state->x2;
+  x1 = (unsigned long int) state->x1;
+
+  return (x2 << 16) + x1;
+}
+
+static double
+rand48_get_double (void * vstate)
+{
+  rand48_state_t *state = (rand48_state_t *) vstate;
+
+  rand48_advance (state) ;  
+
+  return (ldexp((double) state->x2, -16)
+          + ldexp((double) state->x1, -32) 
+          + ldexp((double) state->x0, -48)) ;
+}
+
+static void
+rand48_set (void *vstate, unsigned long int s)
+{
+  rand48_state_t *state = (rand48_state_t *) vstate;
+
+  if (s == 0)  /* default seed */
+    {
+      state->x0 = 0x330E ;
+      state->x1 = 0xABCD ;
+      state->x2 = 0x1234 ;
+    }
+  else 
+    {
+      state->x0 = 0x330E ;
+      state->x1 = s & 0xFFFF ;
+      state->x2 = (s >> 16) & 0xFFFF ;
+    }
+
+  return;
+}
+
+static const gsl_rng_type rand48_type =
+{"rand48",                      /* name */
+ 0xffffffffUL,                  /* RAND_MAX */
+ 0,                             /* RAND_MIN */
+ sizeof (rand48_state_t),
+ &rand48_set,
+ &rand48_get,
+ &rand48_get_double
+};
+
+const gsl_rng_type *gsl_rng_rand48 = &rand48_type;