56 lines
1 KiB
ArmAsm
56 lines
1 KiB
ArmAsm
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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Fast, simple, yet decent quality random number generator based on
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* a paper by David G. Carta ("Two Fast Implementations of the
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* `Minimal Standard' Random Number Generator," Communications of the
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* ACM, January, 1990).
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*
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* Copyright (C) 2002 Hewlett-Packard Co
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* David Mosberger-Tang <davidm@hpl.hp.com>
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*/
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#include <asm/asmmacro.h>
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#define a r2
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#define m r3
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#define lo r8
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#define hi r9
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#define t0 r16
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#define t1 r17
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#define seed r32
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GLOBAL_ENTRY(carta_random32)
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movl a = (16807 << 16) | 16807
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;;
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pmpyshr2.u t0 = a, seed, 0
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pmpyshr2.u t1 = a, seed, 16
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;;
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unpack2.l t0 = t1, t0
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dep m = -1, r0, 0, 31
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;;
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zxt4 lo = t0
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shr.u hi = t0, 32
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;;
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dep t0 = 0, hi, 15, 49 // t0 = (hi & 0x7fff)
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;;
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shl t0 = t0, 16 // t0 = (hi & 0x7fff) << 16
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shr t1 = hi, 15 // t1 = (hi >> 15)
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;;
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add lo = lo, t0
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;;
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cmp.gtu p6, p0 = lo, m
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;;
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(p6) and lo = lo, m
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;;
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(p6) add lo = 1, lo
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;;
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add lo = lo, t1
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;;
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cmp.gtu p6, p0 = lo, m
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;;
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(p6) and lo = lo, m
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;;
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(p6) add lo = 1, lo
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br.ret.sptk.many rp
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END(carta_random32)
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