NeXT Education Software Sampler 1992 Fall/NeXT Education Software Sampler 1992 Fall.iso/SoundAndMusic/cmix/lib/buzz.c

C/C++ Source or Header | 1991-02-25 | 490 b | 25 lines

#define  ABS(x) ((x < 0) ? (-x) : (x))
#define EPS .1e-06
float buzz(amp,si,hn,f,phs)
float amp,si,hn,*f,*phs;
{
    register j,k;
    float q,d,h2n,h2np1;
    j = *phs;
    k = (j+1) % 1024;
    h2n = 2. * hn;
    h2np1 = h2n + 1.;
    q = (int)((*phs - (float)j) * h2np1)/h2np1;
    d = *(f+j);
    d += (*(f+k)-d)*q;
    if(ABS(d) < EPS) q = amp;
          else {
        k = (long)(h2np1 * *phs) % 1024;
        q = amp * (*(f+k)/d - 1.)/h2n;
        }
    *phs += si;
    while(*phs >= 1024.)
        *phs -= 1024.;
    return(q);
}