Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / arch / ia64 / lib / carta_random.S

diff --git a/kernel/arch/ia64/lib/carta_random.S b/kernel/arch/ia64/lib/carta_random.S
new file mode 100644 (file)
index 0000000..d0674c3
--- /dev/null
+++ b/kernel/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)