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Diffstat (limited to 'arch/ia64/lib/carta_random.S')
| -rw-r--r-- | arch/ia64/lib/carta_random.S | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/arch/ia64/lib/carta_random.S b/arch/ia64/lib/carta_random.S new file mode 100644 index 000000000..1a4a639dc --- /dev/null +++ b/arch/ia64/lib/carta_random.S @@ -0,0 +1,55 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * 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) |