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tag: phobos-0.104
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// random.d
// www.digitalmars.com
module std.random;
// Segments of the code in this file Copyright (c) 1997 by Rick Booth
// From "Inner Loops" by Rick Booth, Addison-Wesley
version (Win32)
{
extern(Windows) int QueryPerformanceCounter(ulong *count);
}
version (linux)
{
private import std.c.linux.linux;
}
/* ===================== Random ========================= */
// BUG: not multithreaded
private uint seed; // starting seed
private uint index; // ith random number
void rand_seed(uint s, uint i)
{
seed = s;
index = i;
}
uint rand()
{
static uint xormix1[20] =
[
0xbaa96887, 0x1e17d32c, 0x03bcdc3c, 0x0f33d1b2,
0x76a6491d, 0xc570d85d, 0xe382b1e3, 0x78db4362,
0x7439a9d4, 0x9cea8ac5, 0x89537c5c, 0x2588f55d,
0x415b5e1d, 0x216e3d95, 0x85c662e7, 0x5e8ab368,
0x3ea5cc8c, 0xd26a0f74, 0xf3a9222b, 0x48aad7e4
];
static uint xormix2[20] =
[
0x4b0f3b58, 0xe874f0c3, 0x6955c5a6, 0x55a7ca46,
0x4d9a9d86, 0xfe28a195, 0xb1ca7865, 0x6b235751,
0x9a997a61, 0xaa6e95c8, 0xaaa98ee1, 0x5af9154c,
0xfc8e2263, 0x390f5e8c, 0x58ffd802, 0xac0a5eba,
0xac4874f6, 0xa9df0913, 0x86be4c74, 0xed2c123b
];
uint hiword, loword, hihold, temp, itmpl, itmph, i;
loword = seed;
hiword = index++;
for (i = 0; i < 4; i++) // loop limit can be 2..20, we choose 4
{
hihold = hiword; // save hiword for later
temp = hihold ^ xormix1[i]; // mix up bits of hiword
itmpl = temp & 0xffff; // decompose to hi & lo
itmph = temp >> 16; // 16-bit words
temp = itmpl * itmpl + ~(itmph * itmph); // do a multiplicative mix
temp = (temp >> 16) | (temp << 16); // swap hi and lo halves
hiword = loword ^ ((temp ^ xormix2[i]) + itmpl * itmph); //loword mix
loword = hihold; // old hiword is loword
}
return hiword;
}
static this()
{
ulong s;
version(Win32)
{
QueryPerformanceCounter(&s);
}
version(linux)
{
// time.h
// sys/time.h
timeval tv;
if (gettimeofday(&tv, null))
{ // Some error happened - try time() instead
s = time(null);
}
else
{
s = (cast(long)tv.tv_sec << 32) + tv.tv_usec;
}
}
rand_seed(cast(uint) s, cast(uint)(s >> 32));
}
unittest
{
static uint results[10] =
[
0x8c0188cb,
0xb161200c,
0xfc904ac5,
0x2702e049,
0x9705a923,
0x1c139d89,
0x346b6d1f,
0xf8c33e32,
0xdb9fef76,
0xa97fcb3f
];
int i;
uint seedsave = seed;
uint indexsave = index;
rand_seed(1234, 5678);
for (i = 0; i < 10; i++)
{ uint r = rand();
//printf("0x%x,\n", rand());
assert(r == results[i]);
}
seed = seedsave;
index = indexsave;
}
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