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