patch-2.4.21 linux-2.4.21/arch/ia64/lib/carta_random.S

• Lines: 55
• Date: 2003-06-13 07:51:29.000000000 -0700
• Orig file: linux-2.4.20/arch/ia64/lib/carta_random.S
• Orig date: 1969-12-31 16:00:00.000000000 -0800

diff -urN linux-2.4.20/arch/ia64/lib/carta_random.S linux-2.4.21/arch/ia64/lib/carta_random.S
@@ -0,0 +1,54 @@
+/*
+ * Fast, simple, yet decent quality random number generator based on
+ * a paper by David G. Carta ("Two Fast Implementations of the
+ * `Minimal Standard' Random Number Generator," Communications of the
+ * ACM, January, 1990).
+ *
+ * Copyright (C) 2002 Hewlett-Packard Co
+ *	David Mosberger-Tang <davidm@hpl.hp.com>
+ */
+
+#include <asm/asmmacro.h>
+
+#define a	r2
+#define m	r3
+#define lo	r8
+#define hi	r9
+#define t0	r16
+#define t1	r17
+#define	seed	r32
+
+GLOBAL_ENTRY(carta_random32)
+	movl	a = (16807 << 16) | 16807
+	;;
+	pmpyshr2.u t0 = a, seed, 0
+	pmpyshr2.u t1 = a, seed, 16
+	;;
+	unpack2.l t0 = t1, t0
+	dep	m = -1, r0, 0, 31
+	;;
+	zxt4	lo = t0
+	shr.u	hi = t0, 32
+	;;
+	dep	t0 = 0, hi, 15, 49	// t0 = (hi & 0x7fff)
+	;;
+	shl	t0 = t0, 16		// t0 = (hi & 0x7fff) << 16
+	shr	t1 = hi, 15		// t1 = (hi >> 15)
+	;;
+	add	lo = lo, t0
+	;;
+	cmp.gtu	p6, p0 = lo, m
+	;;
+(p6)	and	lo = lo, m
+	;;
+(p6)	add	lo = 1, lo
+	;;
+	add	lo = lo, t1
+	;;
+	cmp.gtu p6, p0 = lo, m
+	;;
+(p6)	and	lo = lo, m
+	;;
+(p6)	add	lo = 1, lo
+	br.ret.sptk.many rp
+END(carta_random32)