#include <math.h>

#define DUZINA_BAFERA 256

int Mag [DUZINA_BAFERA/2];
int sinus[DUZINA_BAFERA];
int cosinus[DUZINA_BAFERA];

int signal[DUZINA_BAFERA] = {
     0,  1771,  -163,   721,  -721,  1608,  2288,   -47,  1022,   -46,  2266, 1638,
  -728,   720,  -163,  1757,    33, -1783,   161,  -722,   716, -1576, -2313,   49,
 -1022,    46, -2242, -1670,   734,  -719,   164, -1742,   -67,  1798,
  -160,   722,  -709,  1545,  2335,   -49,  1021,   -44,  2218,  1701,  -738,
   718,  -165,  1728,   101, -1810,   158,  -722,   703, -1513, -2358,    47,
 -1020,    42, -2194, -1730,   743,  -715,   163, -1713,  -135,  1823,  -156,
   721,  -694,  1481,  2380,   -48,  1018,   -40,  2169,  1761,  -747,   713,
  -163,  1697,   170, -1835,   154,  -721,   687, -1449, -2401,    47, -1016,
    36, -2144, -1792,   751,  -711,   162, -1682,  -203,  1846,  -150,   719,
  -678,  1418,  2423,   -45,  1014,   -33,  2120,  1822,  -753,   707,  -162,
  1665,   237, -1858,   147,  -718,   672, -1385, -2444,    43, -1012,    30,
 -2094, -1852,   756,  -704,   159, -1650,  -272,  1868,  -143,   717,  -662,
  1353,  2464,   -41,  1010,   -27,  2070,  1880,  -758,   700,  -157,  1633,
   305, -1880,   139,  -714,   654, -1322, -2485,    38, -1007,    22, -2044,
 -1910,   760,  -696,   154, -1616,  -339,  1889,  -134,   713,  -644,  1290,
  2504,   -35,  1004,   -18,  2018,  1939,  -762,   692,  -152,  1599,   372,
 -1898,   130,  -710,   634, -1257, -2525,    32, -1001,    12, -1992, -1969,
   763,  -688,   149, -1580,  -406,  1907,  -124,   707,  -624,  1225,  2544,
   -27,   996,    -6,  1965,  1996,  -764,   683,  -146,  1563,   440, -1915,
   119,  -704,   614, -1192, -2562,    23,  -993,     1, -1939, -2025,   763,
  -677,   142, -1545,  -473,  1924,  -113,   700,  -603,  1159,  2581,   -19,
   989,     3,  1913,  2052,  -763,   672,  -138,  1527,   506, -1931,   107,
  -697,   592, -1127, -2600,    13,  -984,   -10, -1886, -2080,   761,  -666,
   135, -1508
};

void trigLookup(int sinus[], int cosinus[], int duzina) {
    int i;
    for(i=0; i<duzina; i++){
        sinus[i]=(int)(sin(6.28*i/duzina)*32767);  // Q15
        cosinus[i]=(int)(cos(6.28*i/duzina)*32767);  // Q15
    }
}

void dft(int x[], int N) {
    int i, k;
    long xRe, xIm;
    for (k=0; k<(N/2); k++) {
        xRe=0;
        xIm=0;
        for(i=0; i<N; i++){
            xRe += ((long)x[i]*(long)cosinus[(k*i)%N])>>15;
            xIm += ((long)x[i]*(long)sinus[(k*i)%N])>>15;
        }
        Mag[k]=(((long)(xRe>>7)*(long)(xRe>>7))+((long)(xIm>>7)*(long)(xIm>>7)))>>11;
    }
}

void main(void) {
    int i;

    // Generisi lookup tabele za sin i cos
    trigLookup(sinus, cosinus, DUZINA_BAFERA);

    // Uradi DFT signala. Spektralne komponente se nalaze u vektoru Mag[]
    dft(signal, DUZINA_BAFERA);

    // Fs = 8kHz, broj odbiraka = 256
    // rezolucija = 8000/256 = 31.25
    // k1 = 8, f1 = 31.25 * k1 = 250
    // k2 = 56, f2 = 1750
    // k3 = 104, f3 = 31.25 * 104 = 3250

    while(1);
}