[PD-dev] Random method in noise~ question....

[chun lee]

Hi there:

Out of curiosity, I thought I will take a look at how [noise~] is
implemented. While knowing just enough C to write little externals, I am a
bit puzzled at the method in which the random number is obtained in here as
I only know of rand() method in ANSI C. I also looked at the code for
[random] and they look similar. Homebrew?

I wonder if anyone could provide some comments on the code or explain a
little so that I can know how it works.

static t_int *noise_perform(t_int *w)
{
    t_float *out = (t_float *)(w[1]);
    int *vp = (int *)(w[2]);
    int n = (int)(w[3]);
    int val = *vp;
    while (n--)
    {
        *out++ = ((float)((val & 0x7fffffff) - 0x40000000)) *
            (float)(1.0 / 0x40000000);
        val = val * 435898247 + 382842987;
    }
    *vp = val;
    return (w+4);
}


Many thanks

Yours

CHUN