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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libgfortran/intrinsics/rand.c | |
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Diffstat (limited to 'libgfortran/intrinsics/rand.c')
-rw-r--r-- | libgfortran/intrinsics/rand.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/libgfortran/intrinsics/rand.c b/libgfortran/intrinsics/rand.c new file mode 100644 index 000000000..369feaeaf --- /dev/null +++ b/libgfortran/intrinsics/rand.c @@ -0,0 +1,136 @@ +/* Implementation of the IRAND, RAND, and SRAND intrinsics. + Copyright (C) 2004, 2005, 2007, 2009 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 |