Parth Chandak / Mbed 2 deprecated c_FFT_Function

fft_implementation_draft1

Dependencies:   mbed

main.cpp@0:b723ff6df537, 2018-03-07 (annotated)

Committer:
parthchandak02
Date:
Wed Mar 07 11:06:31 2018 +0000
Revision:
0:b723ff6df537
Child:
1:b86b60ae81af
draft1

Who changed what in which revision?

UserRevisionLine numberNew contents of line
parthchandak02 0:b723ff6df537 1 #include <mbed.h>
parthchandak02 0:b723ff6df537 2
parthchandak02 0:b723ff6df537 3 #include <iostream>
parthchandak02 0:b723ff6df537 4 #include <complex>
parthchandak02 0:b723ff6df537 5 #define MAX 2048
parthchandak02 0:b723ff6df537 6 #define M_PI 3.1415926535897932384
parthchandak02 0:b723ff6df537 7
parthchandak02 0:b723ff6df537 8 using namespace std;
parthchandak02 0:b723ff6df537 9
parthchandak02 0:b723ff6df537 10
parthchandak02 0:b723ff6df537 11 float s;
parthchandak02 0:b723ff6df537 12 float a = 1; //amplitude
parthchandak02 0:b723ff6df537 13 float pi = 3.142; //pi
parthchandak02 0:b723ff6df537 14 float o = 1/2; //offset
parthchandak02 0:b723ff6df537 15 float time_count = 0;
parthchandak02 0:b723ff6df537 16
parthchandak02 0:b723ff6df537 17 int i = 0; //iteration counter
parthchandak02 0:b723ff6df537 18 int f1 = 100; //frequency in Hz
parthchandak02 0:b723ff6df537 19 //int f2 = 250; //frequency in Hz
parthchandak02 0:b723ff6df537 20 //int f3 = 500; //frequency in Hz
parthchandak02 0:b723ff6df537 21 float step = 1/(5*f1);
parthchandak02 0:b723ff6df537 22 float time[MAX] = 0;
parthchandak02 0:b723ff6df537 23
parthchandak02 0:b723ff6df537 24 float* generateTimeVector (float* timeVec, int vecSize, float stepSize)
parthchandak02 0:b723ff6df537 25 {
parthchandak02 0:b723ff6df537 26 for(int i=1; i<=vecSize; i++)
parthchandak02 0:b723ff6df537 27 {
parthchandak02 0:b723ff6df537 28 timeVec[i] = i*stepSize;
parthchandak02 0:b723ff6df537 29 }
parthchandak02 0:b723ff6df537 30 return timeVec;
parthchandak02 0:b723ff6df537 31 }
parthchandak02 0:b723ff6df537 32
parthchandak02 0:b723ff6df537 33 bool set1 = false;
parthchandak02 0:b723ff6df537 34 bool set2 = false;
parthchandak02 0:b723ff6df537 35 bool set3 = false;
parthchandak02 0:b723ff6df537 36
parthchandak02 0:b723ff6df537 37 void sineVector (complex<double>* sineVector, int i, int freqHz, int amplitude, int offset);
parthchandak02 0:b723ff6df537 38
parthchandak02 0:b723ff6df537 39 int log2(int N) /*function to calculate the log2(.) of int numbers*/
parthchandak02 0:b723ff6df537 40 {
parthchandak02 0:b723ff6df537 41 int k = N, i = 0;
parthchandak02 0:b723ff6df537 42 while(k) {
parthchandak02 0:b723ff6df537 43 k >>= 1;
parthchandak02 0:b723ff6df537 44 i++;
parthchandak02 0:b723ff6df537 45 }
parthchandak02 0:b723ff6df537 46 return i - 1;
parthchandak02 0:b723ff6df537 47 }
parthchandak02 0:b723ff6df537 48
parthchandak02 0:b723ff6df537 49 int check(int n) //checking if the number of element is a power of 2
parthchandak02 0:b723ff6df537 50 {
parthchandak02 0:b723ff6df537 51 return n > 0 && (n & (n - 1)) == 0;
parthchandak02 0:b723ff6df537 52 }
parthchandak02 0:b723ff6df537 53
parthchandak02 0:b723ff6df537 54 int reverse(int N, int n) //calculating revers number
parthchandak02 0:b723ff6df537 55 {
parthchandak02 0:b723ff6df537 56 int j, p = 0;
parthchandak02 0:b723ff6df537 57 for(j = 1; j <= log2(N); j++) {
parthchandak02 0:b723ff6df537 58 if(n & (1 << (log2(N) - j)))
parthchandak02 0:b723ff6df537 59 p |= 1 << (j - 1);
parthchandak02 0:b723ff6df537 60 }
parthchandak02 0:b723ff6df537 61 return p;
parthchandak02 0:b723ff6df537 62 }
parthchandak02 0:b723ff6df537 63
parthchandak02 0:b723ff6df537 64 void ordina(complex<double>* f1, int N) //using the reverse order in the array
parthchandak02 0:b723ff6df537 65 {
parthchandak02 0:b723ff6df537 66 complex<double> f2[MAX];
parthchandak02 0:b723ff6df537 67 for(int i = 0; i < N; i++)
parthchandak02 0:b723ff6df537 68 f2[i] = f1[reverse(N, i)];
parthchandak02 0:b723ff6df537 69 for(int j = 0; j < N; j++)
parthchandak02 0:b723ff6df537 70 f1[j] = f2[j];
parthchandak02 0:b723ff6df537 71 }
parthchandak02 0:b723ff6df537 72
parthchandak02 0:b723ff6df537 73 void transform(complex<double>* f, int N) //
parthchandak02 0:b723ff6df537 74 {
parthchandak02 0:b723ff6df537 75 ordina(f, N); //first: reverse order
parthchandak02 0:b723ff6df537 76 complex<double> *W;
parthchandak02 0:b723ff6df537 77 W = (complex<double> *)malloc(N / 2 * sizeof(complex<double>));
parthchandak02 0:b723ff6df537 78 W[1] = polar(1., -2. * M_PI / N);
parthchandak02 0:b723ff6df537 79 W[0] = 1;
parthchandak02 0:b723ff6df537 80 for(int i = 2; i < N / 2; i++)
parthchandak02 0:b723ff6df537 81 W[i] = pow(W[1], i);
parthchandak02 0:b723ff6df537 82 int n = 1;
parthchandak02 0:b723ff6df537 83 int a = N / 2;
parthchandak02 0:b723ff6df537 84 for(int j = 0; j < log2(N); j++) {
parthchandak02 0:b723ff6df537 85 for(int i = 0; i < N; i++) {
parthchandak02 0:b723ff6df537 86 if(!(i & n)) {
parthchandak02 0:b723ff6df537 87 complex<double> temp = f[i];
parthchandak02 0:b723ff6df537 88 complex<double> Temp = W[(i * a) % (n * a)] * f[i + n];
parthchandak02 0:b723ff6df537 89 f[i] = temp + Temp;
parthchandak02 0:b723ff6df537 90 f[i + n] = temp - Temp;
parthchandak02 0:b723ff6df537 91 }
parthchandak02 0:b723ff6df537 92 }
parthchandak02 0:b723ff6df537 93 n *= 2;
parthchandak02 0:b723ff6df537 94 a = a / 2;
parthchandak02 0:b723ff6df537 95 }
parthchandak02 0:b723ff6df537 96 }
parthchandak02 0:b723ff6df537 97
parthchandak02 0:b723ff6df537 98 void FFT(complex<double>* f, int N, double d)
parthchandak02 0:b723ff6df537 99 {
parthchandak02 0:b723ff6df537 100 transform(f, N);
parthchandak02 0:b723ff6df537 101 for(int i = 0; i < N; i++)
parthchandak02 0:b723ff6df537 102 f[i] *= d; //multiplying by step
parthchandak02 0:b723ff6df537 103 }
parthchandak02 0:b723ff6df537 104
parthchandak02 0:b723ff6df537 105 int main()
parthchandak02 0:b723ff6df537 106 {
parthchandak02 0:b723ff6df537 107 complex<double> vec[MAX];
parthchandak02 0:b723ff6df537 108 for (i = 0; i < MAX; i++)
parthchandak02 0:b723ff6df537 109 {
parthchandak02 0:b723ff6df537 110 sineVector(vec, i, f1, a, 0);
parthchandak02 0:b723ff6df537 111 }
parthchandak02 0:b723ff6df537 112
parthchandak02 0:b723ff6df537 113 FFT(vec, MAX, 1); //'d' should be 1 in order to have the same results of matlab fft(.)
parthchandak02 0:b723ff6df537 114 cout << "...printing the FFT of the array specified" << endl;
parthchandak02 0:b723ff6df537 115 for(int j = 0; j < MAX; j++)
parthchandak02 0:b723ff6df537 116 {
parthchandak02 0:b723ff6df537 117 cout << vec[j] << endl;
parthchandak02 0:b723ff6df537 118 }
parthchandak02 0:b723ff6df537 119
parthchandak02 0:b723ff6df537 120 return 0;
parthchandak02 0:b723ff6df537 121 }
parthchandak02 0:b723ff6df537 122
parthchandak02 0:b723ff6df537 123
parthchandak02 0:b723ff6df537 124 void sineVector (complex<double>* sineVector, int i, int freqHz, int amplitude, int offset)
parthchandak02 0:b723ff6df537 125 {
parthchandak02 0:b723ff6df537 126 sineVector[i] = offset + amplitude*sin((pi/180) * freqHz * i);
parthchandak02 0:b723ff6df537 127 }