# rand48.h.patch   [plain text]

```--- rand48.h.orig	2003-05-20 15:21:02.000000000 -0700
+++ rand48.h	2005-11-03 14:06:17.000000000 -0800
@@ -19,8 +19,6 @@
#include <math.h>
#include <stdlib.h>

-void		_dorand48(unsigned short[3]);
-
#define	RAND48_SEED_0	(0x330e)
#define	RAND48_SEED_1	(0xabcd)
#define	RAND48_SEED_2	(0x1234)
@@ -29,4 +27,55 @@
#define	RAND48_MULT_2	(0x0005)

+typedef unsigned long long uint48;
+
+extern uint48 _rand48_seed;
+extern uint48 _rand48_mult;
+
+#define TOUINT48(x,y,z) \
+	((uint48)(x) + (((uint48)(y)) << 16) + (((uint48)(z)) << 32))
+
+#define RAND48_SEED	TOUINT48(RAND48_SEED_0, RAND48_SEED_1, RAND48_SEED_2)
+#define RAND48_MULT	TOUINT48(RAND48_MULT_0, RAND48_MULT_1, RAND48_MULT_2)
+
+	(l) = TOUINT48((x)[0], (x)[1], (x)[2])
+
+#define STORERAND48(l,x) \
+	(x)[0] = (unsigned short)(l); \
+	(x)[1] = (unsigned short)((l) >> 16); \
+	(x)[2] = (unsigned short)((l) >> 32)
+
+#define _DORAND48(l) \
+	(l) = (l) * _rand48_mult + _rand48_add
+
+#define DORAND48(l,x) \
+	_DORAND48(l); \
+	STORERAND48(l, x)
+
+#include "fpmath.h"
+
+/*
+ * Optimization for speed: avoid int-to-double conversion.  Assume doubles
+ * are IEEE-754 and insert the bits directly.  To normalize, the (1 << 52)
+ * is the hidden bit, which the first set bit is shifted to.
+ */
+#define ERAND48_BEGIN \
+	union { \
+		union IEEEd2bits ieee; \
+		unsigned long long l; \
+	} u; \
+	int s
+
+#define ERAND48_END(x) \
+	u.l = ((x) & 0xffffffffffffULL); \
+	if (u.l == 0) \
+		return 0.0; \
+	u.l <<= 5; \
+	for(s = 0; !(u.l & (1LL << 52)); s++, u.l <<= 1) {} \
+	u.ieee.bits.exp = 1022 - s; \
+	return u.ieee.d
+
#endif /* _RAND48_H_ */
```