#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
/* Implement frand using GCC's statement-expression extension. */
# define frand(f) \
- ({ double tmp = (((double) random()) / \
- (((double) ((unsigned int)~0)) / ((double) (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) ((unsigned int)~0)) / ((double) (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__ */