I've posted it originally in the Electronics forum but guess here's the place for this kind of question.

Hello. My task is to simulate sinusoidal generator with PSIM using two methods - absolute values and table of differences. Parameteres of the generator are : Amplitude u=255 V, frequency f=50H; sampling frequency 5kHz. I have created arrays of norm and diff values with C. Now I've thought of a method of iterating through elements of the array and in each time step, and pick the corresponding value. If function is in the first quarter - iterate array from the beginning. If it will be in the second one - iterate arrayfrom the end. If quarter is third - iterate from the beginning with values multiplied by one. Finally in the fourth one - go through array from the end, multiplying elements by -1.

Now I should somehow create a function, which in each time step takes value from the array, and depending on the place on the sinusoid either multiplies it by -1 or not. But how can I store the information which element from the array should be taken now and if array should be iterated from the beggining or the end ?

Because the previous post had been deleted, here are tho seurce codes once again. First calculated arrays :

int main(){
    double amp = 128;                             
    float norm[25];
    float diff[25];
    float s;
    int i;

    for(i=0; i< 25; i++){
        if(i == 0){
            norm = 0;
        }
        norm = i*2*M_PI/100;
        s = amp*sin(norm);
        norm = s;
    }
    
    for(i=0; i<25; i++){
        if(i == 0){
            diff = 0;     
        }
        diff = norm - norm[i-1];
    }
    
    return 0;  
}

and here's template for the dll function :

__declspec(dllexport)opc1(double t, double dt, double *in, double *out){
    double u = in[0];
    out[0] = y;
}

 

You can work out which phase you are in from the angle.
0-90 = phase 1, 90-180-= phase 2 etc.

 

this leaves only issue with finding which element from the array should be taken next.

 

and what about storing the current counter value in a file ? Will the system manage to read/write from/to a file 5k times per second ?