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| /* 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)
|
|
