aboutsummaryrefslogtreecommitdiff
path: root/arch/ia64/lib/carta_random.S
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/ia64/lib/carta_random.S
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/ia64/lib/carta_random.S')
-rw-r--r--arch/ia64/lib/carta_random.S54
1 files changed, 54 insertions, 0 deletions
diff --git a/arch/ia64/lib/carta_random.S b/arch/ia64/lib/carta_random.S
new file mode 100644
index 00000000000..d0674c36036
--- /dev/null
+++ b/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)