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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgfortran/] [intrinsics/] [rand.c] - Rev 848
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/* 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
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