/usr/share/nickle/prng.5c is in nickle 2.77-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 | /*
* Use ARC4 to generate large random numbers
*
* Bart 1999/2
*
* Modified 2003/4 to support /dev/random
*/
autoload ARC4;
namespace PRNG {
import File;
global bool setkey = false;
public void srandom(int s)
/*
* Seed the PRNG with 's'
*/
{
ARC4::nsetkey(10, abs (s));
setkey = true;
}
public void dev_srandom(int nbits)
/*
* Use 'nbits' of /dev/urandom to seed the PRNG
*/
{
twixt(file f = open("/dev/urandom", "r"); close(f)) {
int seed = 0;
while (nbits >= 8) {
seed = (seed << 8) | getb(f);
nbits -= 8;
}
if (nbits > 0)
seed = (seed << nbits) | (getb(f) & ((1 << nbits) - 1));
srandom(seed);
}
}
public int randbits(int n)
/*
* returns an 'n'-*bit* random number in 0..(2**'n')-1
*/
{
int q = n >> 3;
int r = n & 7;
if (!setkey)
srandom(0);
int acc = ARC4::streambyte() >> (8 - r);
while (q > 0) {
--q;
acc += ARC4::streambyte() << (8 * q + r);
}
return acc;
}
public int randint(int n)
/*
* Returns a random integer in the range 0..'n'-1
*/
{
return randbits(32 + bit_width (n)) % n;
}
public void shuffle(&poly[*] a)
/*
* Randomly shuffle 'a' in place
*/
{
int na = dim(a);
for (int i = 0; i < na - 1; i++) {
int j = randint(na - i) + i;
poly tmp = a[i];
a[i] = a[j];
a[j] = tmp;
}
}
}
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