Implementation of the Karplus-Strong algorithm in MSP

t_int *kastro_perform(t_int *w)
{  
	t_float *fb = (t_float *)(w[1]);
	t_float *freq = (t_float *)(w[2]);
	t_float *damp= (t_float *)(w[3]);
	t_float *atten= (t_float *)(w[4]);
	
	t_float *inharm = (t_float *)(w[5]);
	t_float *out = (t_float *)(w[6]);
	t_kastro *x = (t_kastro *)(w[7]);
	int n_tick = (int)(w[8]);

		float yn,xn,ym1 = x->b_ym1,ym2 = x->b_ym2;
 float ym1all=x->b_ym1all,ym2all=x-> b_ym2all,xm2=x->b_xm2, xm1=x->b_xm1;
	
	float *vinut;
	float *vinbridge;
	int posr=x->v_posright;
	int posl=x->v_posleft;
	long i;
	double wn, sn, cs, alpha, a0, a1, a2, b0, b1, b2;
	double sr =x->srate;
	double gain = 1.0; // x->f_gain;
    float a0l,a1l,a2l,b1l,b2l;
    float alphar;
    float ynout;
    float ynn;
	float vin, vh;
	float srate=x->srate;
	float del_tot;
	int samp_rperiod;
	int samp_lperiod;
	
	vinut=x->vinut;
	
	if (x->v_obj.z_disabled) // if the user disactivates the object from the dsp chain
		goto out;
    for(i=0; i<n_tick; i++)
	{

    del_tot=srate/(freq[i]);    //total length of the delay line
     
	samp_rperiod=(int)del_tot;   //integer part
	if(samp_rperiod<0) samp_rperiod = 0;
	if(samp_rperiod>BUFSIZE-1) samp_rperiod = BUFSIZE-1;
		alphar=(float)(del_tot-samp_rperiod);   //fractional part
 
	vin = vinut[(posr+i + BUFSIZE - samp_rperiod)% BUFSIZE]
	*(1-alphar)+(vinut[(posr+i+ BUFSIZE - samp_rperiod-1)% BUFSIZE])*(alphar) ;

//check if damping is >= 1, to avoid to distroy the filter
	if (damp[i]>0.99999) 
 damp[i]=0.999;
 if (damp[i]<0.000001) 
 damp[i]=0.000001;
 
 //check for attenuation too
 
		if (atten[i]>1) 
 atten[i]=1;
 if (atten[i]<0.00001) 
 atten[i]=0.00001;

//low-pass filter for damping

	  ynn = atten[i]*(damp[i]*vin +((1-damp[i]) *ym1));
	//update
	
		ym1 = vin;
	    
    vh=fb[i]+ynn;

		
	vinut[(posr+i+BUFSIZE)%BUFSIZE] =vh;	
       out[i]=vh;

}
posr=(posr+n_tick)%BUFSIZE;

	x->b_ym1 = ym1;
	x->b_ym2 = ym2;

	x->b_ym2all = ym2all;
	x->b_xm1 = xm1;
	
	x->b_ym1all = ym1all;
	x->v_posright=posr;
	x->v_posleft=posl;
	
out:
	return (w+9);
 }