137 lines
3.6 KiB
C
137 lines
3.6 KiB
C
/* Implementation of the IRAND, RAND, and SRAND intrinsics.
|
|
Copyright (C) 2004-2020 Free Software Foundation, Inc.
|
|
Contributed by Steven G. Kargl <kargls@comcast.net>.
|
|
|
|
This file is part of the GNU Fortran 95 runtime library (libgfortran).
|
|
|
|
Libgfortran 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 3 of the License, or (at your option) any later version.
|
|
|
|
Libgfortran 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.
|
|
|
|
Under Section 7 of GPL version 3, you are granted additional
|
|
permissions described in the GCC Runtime Library Exception, version
|
|
3.1, as published by the Free Software Foundation.
|
|
|
|
You should have received a copy of the GNU General Public License and
|
|
a copy of the GCC Runtime Library Exception along with this program;
|
|
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
/* Simple multiplicative congruent algorithm.
|
|
The period of this generator is approximately 2^31-1, which means that
|
|
it should not be used for anything serious. The implementation here
|
|
is based of an algorithm from S.K. Park and K.W. Miller, Comm. ACM,
|
|
31, 1192-1201 (1988). It is also provided solely for compatibility
|
|
with G77. */
|
|
|
|
#include "libgfortran.h"
|
|
#include <gthr.h>
|
|
|
|
#define GFC_RAND_A 16807
|
|
#define GFC_RAND_M 2147483647
|
|
#define GFC_RAND_M1 (GFC_RAND_M - 1)
|
|
|
|
static GFC_UINTEGER_8 rand_seed = 1;
|
|
#ifdef __GTHREAD_MUTEX_INIT
|
|
static __gthread_mutex_t rand_seed_lock = __GTHREAD_MUTEX_INIT;
|
|
#else
|
|
static __gthread_mutex_t rand_seed_lock;
|
|
#endif
|
|
|
|
|
|
/* Set the seed of the irand generator. Note 0 is a bad seed. */
|
|
|
|
static void
|
|
srand_internal (GFC_INTEGER_8 i)
|
|
{
|
|
rand_seed = i ? i : 123459876;
|
|
}
|
|
|
|
extern void PREFIX(srand) (GFC_INTEGER_4 *i);
|
|
export_proto_np(PREFIX(srand));
|
|
|
|
void
|
|
PREFIX(srand) (GFC_INTEGER_4 *i)
|
|
{
|
|
__gthread_mutex_lock (&rand_seed_lock);
|
|
srand_internal (*i);
|
|
__gthread_mutex_unlock (&rand_seed_lock);
|
|
}
|
|
|
|
/* Return an INTEGER in the range [1,GFC_RAND_M-1]. */
|
|
|
|
extern GFC_INTEGER_4 irand (GFC_INTEGER_4 *);
|
|
iexport_proto(irand);
|
|
|
|
GFC_INTEGER_4
|
|
irand (GFC_INTEGER_4 *i)
|
|
{
|
|
GFC_INTEGER_4 j;
|
|
if (i)
|
|
j = *i;
|
|
else
|
|
j = 0;
|
|
|
|
__gthread_mutex_lock (&rand_seed_lock);
|
|
|
|
switch (j)
|
|
{
|
|
/* Return the next RN. */
|
|
case 0:
|
|
break;
|
|
|
|
/* Reset the RN sequence to system-dependent sequence and return the
|
|
first value. */
|
|
case 1:
|
|
srand_internal (0);
|
|
break;
|
|
|
|
/* Seed the RN sequence with j and return the first value. */
|
|
default:
|
|
srand_internal (j);
|
|
break;
|
|
}
|
|
|
|
rand_seed = GFC_RAND_A * rand_seed % GFC_RAND_M;
|
|
j = (GFC_INTEGER_4) rand_seed;
|
|
|
|
__gthread_mutex_unlock (&rand_seed_lock);
|
|
|
|
return j;
|
|
}
|
|
iexport(irand);
|
|
|
|
|
|
/* Return a random REAL in the range [0,1). */
|
|
|
|
extern GFC_REAL_4 PREFIX(rand) (GFC_INTEGER_4 *i);
|
|
export_proto_np(PREFIX(rand));
|
|
|
|
GFC_REAL_4
|
|
PREFIX(rand) (GFC_INTEGER_4 *i)
|
|
{
|
|
GFC_UINTEGER_4 mask;
|
|
#if GFC_REAL_4_RADIX == 2
|
|
mask = ~ (GFC_UINTEGER_4) 0u << (32 - GFC_REAL_4_DIGITS + 1);
|
|
#elif GFC_REAL_4_RADIX == 16
|
|
mask = ~ (GFC_UINTEGER_4) 0u << ((8 - GFC_REAL_4_DIGITS) * 4 + 1);
|
|
#else
|
|
#error "GFC_REAL_4_RADIX has unknown value"
|
|
#endif
|
|
return ((GFC_UINTEGER_4) (irand(i) -1) & mask) * (GFC_REAL_4) 0x1.p-31f;
|
|
}
|
|
|
|
#ifndef __GTHREAD_MUTEX_INIT
|
|
static void __attribute__((constructor))
|
|
init (void)
|
|
{
|
|
__GTHREAD_MUTEX_INIT_FUNCTION (&rand_seed_lock);
|
|
}
|
|
#endif
|