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Diffstat (limited to 'utils/yarandom.h')
| -rw-r--r-- | utils/yarandom.h | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/utils/yarandom.h b/utils/yarandom.h new file mode 100644 index 0000000..711aadd --- /dev/null +++ b/utils/yarandom.h @@ -0,0 +1,103 @@ +/* xscreensaver, Copyright (c) 1997, 1998, 2003 by Jamie Zawinski <jwz@jwz.org> + * + * Permission to use, copy, modify, distribute, and sell this software and its + * documentation for any purpose is hereby granted without fee, provided that + * the above copyright notice appear in all copies and that both that + * copyright notice and this permission notice appear in supporting + * documentation. No representations are made about the suitability of this + * software for any purpose. It is provided "as is" without express or + * implied warranty. + */ + +#ifndef __YARANDOM_H__ +#define __YARANDOM_H__ + +#ifdef HAVE_CONFIG_H +# include "config.h" +#endif + +#ifdef HAVE_INTTYPES_H +# include <inttypes.h> +#endif + +#undef random +#undef rand +#undef drand48 +#undef srandom +#undef srand +#undef srand48 +#undef frand +#undef RAND_MAX + +#ifdef VMS +# include "vms-gtod.h" +#endif + +extern unsigned int ya_random (void); +extern void ya_rand_init (unsigned int); + +#define random() ya_random() +#define RAND_MAX 0xFFFFFFFF + +/*#define srandom(i) ya_rand_init(0)*/ + +/* Define these away to keep people from using the wrong APIs in xscreensaver. + */ +#define rand __ERROR_use_random_not_rand_in_xscreensaver__ +#define drand48 __ERROR_use_frand_not_drand48_in_xscreensaver__ +#define srandom __ERROR_do_not_call_srandom_in_xscreensaver__ +#define srand __ERROR_do_not_call_srand_in_xscreensaver__ +#define srand48 __ERROR_do_not_call_srand48_in_xscreensaver__ +#define ya_rand_init __ERROR_do_not_call_ya_rand_init_in_xscreensaver__ + + +#if defined (__GNUC__) && (__GNUC__ >= 2) + /* Implement frand using GCC's statement-expression extension. */ + +# define frand(f) \ + __extension__ \ + ({ double tmp = ((((double) random()) * ((double) (f))) / \ + ((double) ((unsigned int)~0))); \ + tmp < 0 ? (-tmp) : tmp; }) + +#else /* not GCC2 - implement frand using a global variable.*/ + +static double _frand_tmp_; +# define frand(f) \ + (_frand_tmp_ = ((((double) random()) * ((double) (f))) / \ + ((double) ((unsigned int)~0))), \ + _frand_tmp_ < 0 ? (-_frand_tmp_) : _frand_tmp_) + +#endif /* not GCC2 */ + +/* Compatibility with the xlockmore RNG API + (note that the xlockmore hacks never expect negative numbers.) + */ +#define LRAND() ((long) (random() & 0x7fffffff)) + +/* The first NRAND(n) is much faster, when uint64_t is available to allow it. + * Especially on ARM and other processors without built-in division. + * + * n must be greater than zero. + * + * The division by RAND_MAX+1 should optimize down to a bit shift. + * + * Although the result here is never negative, this needs to return signed + * integers: A binary operator in C requires operands have the same type, and + * if one side is signed and the other is unsigned, but they're both the same + * size, then the signed operand is cast to unsigned, and the result is + * similarly unsigned. This can potentially cause problems when idioms like + * "NRAND(n) * RANDSIGN()" (where RANDSIGN() returns either -1 or 1) is used + * to get random numbers from the range (-n,n). + */ +#ifdef HAVE_INTTYPES_H +# define NRAND(n) ((int32_t) ((uint64_t) random() * (uint32_t) (n) / \ + ((uint64_t) RAND_MAX + 1))) +#else +# define NRAND(n) ((int) (LRAND() % (n))) +#endif + +#define MAXRAND (2147483648.0) /* unsigned 1<<31 as a float */ +#define SRAND(n) /* already seeded by screenhack.c */ + +#endif /* __YARANDOM_H__ */ |