#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define PI (3.14159265358979323846)
#define Q 32768

long s1, s2, amp;
long a, b, a_base;
long sa, sa1, sa2, sb, sb1, sb2;
float r;


void genIIR(float freq) {
    a = round(2 * r * cos(2*PI * freq)*Q);
    b = round(-r * r * Q);
    sa2 = 0;
    sa1 = round(sin(2 * PI * freq)*Q);
}

void genIIRBase(float freq) {
    a_base = round(2 * r * cos(2*PI * freq)*Q);
    b = round(-r * r * Q);
    sb2 = 0;
    sb1 = round(sin(2 * PI * freq)*Q);
}

void getBase() {
    sb = (a_base * sb1 >> 15) + (b * sb2 >> 15);
    sb2 = sb1;
    sb1 = sb;
}

void getSample() {
    sa = (a * sa1 >> 15) + (b * sa2 >> 15);
    sa2 = sa1;
    sa1 = sa;
}

int main() {
    FILE *fptrIn, *fptrOut;

    amp = 32000;
    r = 1.0f;
    float f_sampl = 48000.0;

    const float f_selected = 1336.0/f_sampl;
        const float f_tab[] = {
            697.0/f_sampl,
            770.0/f_sampl,
            852.0/f_sampl,
            941.0/f_sampl
            };


    fptrIn = fopen("dataIn.txt", "r");
    if (fptrIn == NULL) {
        printf("Error! Problem with dataIn file!");
        exit(1);
    }
    fptrOut = fopen("dataOut.txt", "w");
    if (fptrOut == NULL) {
        printf("Error! Problem with dataOut file!");
        exit(1);
    }

    {
        genIIRBase(f_selected);
        int j = 0;
        for (int i = 0; i < 48000; i++) {
            if (i % 12000 == 0) {
                genIIR(f_tab[j]);
                j++;
            }
            getBase();
            getSample();

            s1 = amp * sb;
            s2 = amp * sa;
            fprintf(fptrOut, "%d\n", (int) (s1 + s2));
        }
    }

    fclose(fptrIn);
    fclose(fptrOut);

    printf("Hello world!\n");
    return 0;
}