projects / thirdparty / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
| 1da177e4 LT |
2 | /* |
| 3 | * Fast, simple, yet decent quality random number generator based on | |
| 4 | * a paper by David G. Carta ("Two Fast Implementations of the | |
| 5 | * `Minimal Standard' Random Number Generator," Communications of the | |
| 6 | * ACM, January, 1990). | |
| 7 | * | |
| 8 | * Copyright (C) 2002 Hewlett-Packard Co | |
| 9 | * David Mosberger-Tang <davidm@hpl.hp.com> | |
| 10 | */ | |
| 11 | ||
| 12 | #include <asm/asmmacro.h> | |
| 13 | ||
| 14 | #define a r2 | |
| 15 | #define m r3 | |
| 16 | #define lo r8 | |
| 17 | #define hi r9 | |
| 18 | #define t0 r16 | |
| 19 | #define t1 r17 | |
| 20 | #define seed r32 | |
| 21 | ||
| 22 | GLOBAL_ENTRY(carta_random32) | |
| 23 | movl a = (16807 << 16) | 16807 | |
| 24 | ;; | |
| 25 | pmpyshr2.u t0 = a, seed, 0 | |
| 26 | pmpyshr2.u t1 = a, seed, 16 | |
| 27 | ;; | |
| 28 | unpack2.l t0 = t1, t0 | |
| 29 | dep m = -1, r0, 0, 31 | |
| 30 | ;; | |
| 31 | zxt4 lo = t0 | |
| 32 | shr.u hi = t0, 32 | |
| 33 | ;; | |
| 34 | dep t0 = 0, hi, 15, 49 // t0 = (hi & 0x7fff) | |
| 35 | ;; | |
| 36 | shl t0 = t0, 16 // t0 = (hi & 0x7fff) << 16 | |
| 37 | shr t1 = hi, 15 // t1 = (hi >> 15) | |
| 38 | ;; | |
| 39 | add lo = lo, t0 | |
| 40 | ;; | |
| 41 | cmp.gtu p6, p0 = lo, m | |
| 42 | ;; | |
| 43 | (p6) and lo = lo, m | |
| 44 | ;; | |
| 45 | (p6) add lo = 1, lo | |
| 46 | ;; | |
| 47 | add lo = lo, t1 | |
| 48 | ;; | |
| 49 | cmp.gtu p6, p0 = lo, m | |
| 50 | ;; | |
| 51 | (p6) and lo = lo, m | |
| 52 | ;; | |
| 53 | (p6) add lo = 1, lo | |
| 54 | br.ret.sptk.many rp | |
| 55 | END(carta_random32) |