Parth Chandak / Mbed 2 deprecated c_FFT_Function

fft_implementation_draft1

Dependencies:   mbed

main.cpp@1:b86b60ae81af, 2018-03-25 (annotated)

Committer:
parthchandak02
Date:
Sun Mar 25 18:50:02 2018 +0000
Revision:
1:b86b60ae81af
Parent:
0:b723ff6df537 
mbed LPC1768 C FFT Function Revision 1

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 1:b86b60ae81af 5 #include <cmath>
parthchandak02 1:b86b60ae81af 6
parthchandak02 1:b86b60ae81af 7 #define MAX 256
parthchandak02 0:b723ff6df537 8 #define M_PI 3.1415926535897932384
parthchandak02 0:b723ff6df537 9
parthchandak02 1:b86b60ae81af 10
parthchandak02 1:b86b60ae81af 11 Serial pc(USBTX, USBRX);
parthchandak02 0:b723ff6df537 12 using namespace std;
parthchandak02 0:b723ff6df537 13
parthchandak02 0:b723ff6df537 14
parthchandak02 0:b723ff6df537 15 float s;
parthchandak02 1:b86b60ae81af 16 float a = 1.0; //amplitude
parthchandak02 0:b723ff6df537 17 float pi = 3.142; //pi
parthchandak02 1:b86b60ae81af 18 float o = 1; //offset
parthchandak02 1:b86b60ae81af 19 float time_count = 0.0;
parthchandak02 0:b723ff6df537 20
parthchandak02 0:b723ff6df537 21 int i = 0; //iteration counter
parthchandak02 0:b723ff6df537 22 int f1 = 100; //frequency in Hz
parthchandak02 1:b86b60ae81af 23
parthchandak02 1:b86b60ae81af 24 float step = 1.0/(10.0*f1);
parthchandak02 0:b723ff6df537 25
parthchandak02 1:b86b60ae81af 26 float* generateTimeVector (int vecSize, float stepSize)
parthchandak02 0:b723ff6df537 27 {
parthchandak02 1:b86b60ae81af 28 // pc.printf("\nGenerating Time Vector...\n");
parthchandak02 1:b86b60ae81af 29 float *timeVec = new float[vecSize];
parthchandak02 0:b723ff6df537 30 for(int i=1; i<=vecSize; i++)
parthchandak02 0:b723ff6df537 31 {
parthchandak02 0:b723ff6df537 32 timeVec[i] = i*stepSize;
parthchandak02 1:b86b60ae81af 33 // pc.printf("%f\n",timeVec[i]);
parthchandak02 0:b723ff6df537 34 }
parthchandak02 0:b723ff6df537 35 return timeVec;
parthchandak02 0:b723ff6df537 36 }
parthchandak02 0:b723ff6df537 37
parthchandak02 1:b86b60ae81af 38 float* generateFreqVector(int vecSize, float stepSize)
parthchandak02 1:b86b60ae81af 39 {
parthchandak02 1:b86b60ae81af 40 // pc.printf("\nGenerating Frequency Vector...\n");
parthchandak02 1:b86b60ae81af 41 float *freqVec = new float[vecSize];
parthchandak02 1:b86b60ae81af 42 float v = vecSize;
parthchandak02 1:b86b60ae81af 43 for(int i=1; i<=(vecSize); i++)
parthchandak02 1:b86b60ae81af 44 {
parthchandak02 1:b86b60ae81af 45 freqVec[i] = (1.0/stepSize)*(i/v);
parthchandak02 1:b86b60ae81af 46 // pc.printf("%f\n",freqVec[i]);
parthchandak02 1:b86b60ae81af 47 }
parthchandak02 1:b86b60ae81af 48 return freqVec;
parthchandak02 1:b86b60ae81af 49 }
parthchandak02 1:b86b60ae81af 50
parthchandak02 0:b723ff6df537 51 bool set1 = false;
parthchandak02 0:b723ff6df537 52 bool set2 = false;
parthchandak02 0:b723ff6df537 53 bool set3 = false;
parthchandak02 0:b723ff6df537 54
parthchandak02 1:b86b60ae81af 55 void sineGenerate(complex<double>* sineVector, int index, float time, int freqHz, int amplitude, int offset)
parthchandak02 1:b86b60ae81af 56 {
parthchandak02 1:b86b60ae81af 57 sineVector[index] = offset + amplitude*sin((2*pi) * freqHz * time);
parthchandak02 1:b86b60ae81af 58 // pc.printf("%d, %f\n", index, sineVector[index]);
parthchandak02 1:b86b60ae81af 59 }
parthchandak02 0:b723ff6df537 60 int log2(int N) /*function to calculate the log2(.) of int numbers*/
parthchandak02 0:b723ff6df537 61 {
parthchandak02 0:b723ff6df537 62 int k = N, i = 0;
parthchandak02 0:b723ff6df537 63 while(k) {
parthchandak02 0:b723ff6df537 64 k >>= 1;
parthchandak02 0:b723ff6df537 65 i++;
parthchandak02 0:b723ff6df537 66 }
parthchandak02 0:b723ff6df537 67 return i - 1;
parthchandak02 0:b723ff6df537 68 }
parthchandak02 0:b723ff6df537 69
parthchandak02 0:b723ff6df537 70 int check(int n) //checking if the number of element is a power of 2
parthchandak02 0:b723ff6df537 71 {
parthchandak02 0:b723ff6df537 72 return n > 0 && (n & (n - 1)) == 0;
parthchandak02 0:b723ff6df537 73 }
parthchandak02 0:b723ff6df537 74
parthchandak02 0:b723ff6df537 75 int reverse(int N, int n) //calculating revers number
parthchandak02 0:b723ff6df537 76 {
parthchandak02 0:b723ff6df537 77 int j, p = 0;
parthchandak02 0:b723ff6df537 78 for(j = 1; j <= log2(N); j++) {
parthchandak02 0:b723ff6df537 79 if(n & (1 << (log2(N) - j)))
parthchandak02 0:b723ff6df537 80 p |= 1 << (j - 1);
parthchandak02 0:b723ff6df537 81 }
parthchandak02 0:b723ff6df537 82 return p;
parthchandak02 0:b723ff6df537 83 }
parthchandak02 0:b723ff6df537 84
parthchandak02 0:b723ff6df537 85 void ordina(complex<double>* f1, int N) //using the reverse order in the array
parthchandak02 0:b723ff6df537 86 {
parthchandak02 0:b723ff6df537 87 complex<double> f2[MAX];
parthchandak02 0:b723ff6df537 88 for(int i = 0; i < N; i++)
parthchandak02 0:b723ff6df537 89 f2[i] = f1[reverse(N, i)];
parthchandak02 0:b723ff6df537 90 for(int j = 0; j < N; j++)
parthchandak02 0:b723ff6df537 91 f1[j] = f2[j];
parthchandak02 0:b723ff6df537 92 }
parthchandak02 0:b723ff6df537 93
parthchandak02 0:b723ff6df537 94 void transform(complex<double>* f, int N) //
parthchandak02 0:b723ff6df537 95 {
parthchandak02 0:b723ff6df537 96 ordina(f, N); //first: reverse order
parthchandak02 0:b723ff6df537 97 complex<double> *W;
parthchandak02 0:b723ff6df537 98 W = (complex<double> *)malloc(N / 2 * sizeof(complex<double>));
parthchandak02 0:b723ff6df537 99 W[1] = polar(1., -2. * M_PI / N);
parthchandak02 0:b723ff6df537 100 W[0] = 1;
parthchandak02 0:b723ff6df537 101 for(int i = 2; i < N / 2; i++)
parthchandak02 0:b723ff6df537 102 W[i] = pow(W[1], i);
parthchandak02 0:b723ff6df537 103 int n = 1;
parthchandak02 0:b723ff6df537 104 int a = N / 2;
parthchandak02 0:b723ff6df537 105 for(int j = 0; j < log2(N); j++) {
parthchandak02 0:b723ff6df537 106 for(int i = 0; i < N; i++) {
parthchandak02 0:b723ff6df537 107 if(!(i & n)) {
parthchandak02 0:b723ff6df537 108 complex<double> temp = f[i];
parthchandak02 0:b723ff6df537 109 complex<double> Temp = W[(i * a) % (n * a)] * f[i + n];
parthchandak02 0:b723ff6df537 110 f[i] = temp + Temp;
parthchandak02 0:b723ff6df537 111 f[i + n] = temp - Temp;
parthchandak02 0:b723ff6df537 112 }
parthchandak02 0:b723ff6df537 113 }
parthchandak02 0:b723ff6df537 114 n *= 2;
parthchandak02 0:b723ff6df537 115 a = a / 2;
parthchandak02 0:b723ff6df537 116 }
parthchandak02 0:b723ff6df537 117 }
parthchandak02 0:b723ff6df537 118
parthchandak02 0:b723ff6df537 119 void FFT(complex<double>* f, int N, double d)
parthchandak02 0:b723ff6df537 120 {
parthchandak02 0:b723ff6df537 121 transform(f, N);
parthchandak02 0:b723ff6df537 122 for(int i = 0; i < N; i++)
parthchandak02 0:b723ff6df537 123 f[i] *= d; //multiplying by step
parthchandak02 0:b723ff6df537 124 }
parthchandak02 0:b723ff6df537 125
parthchandak02 0:b723ff6df537 126 int main()
parthchandak02 0:b723ff6df537 127 {
parthchandak02 1:b86b60ae81af 128 float* timeVector = generateTimeVector (MAX, step);
parthchandak02 1:b86b60ae81af 129 float* freqVector = generateFreqVector (MAX, step);
parthchandak02 1:b86b60ae81af 130
parthchandak02 0:b723ff6df537 131 complex<double> vec[MAX];
parthchandak02 0:b723ff6df537 132 for (i = 0; i < MAX; i++)
parthchandak02 0:b723ff6df537 133 {
parthchandak02 1:b86b60ae81af 134 float t = timeVector[i];
parthchandak02 1:b86b60ae81af 135 sineGenerate(vec, i, t, f1, a, 0);
parthchandak02 0:b723ff6df537 136 }
parthchandak02 0:b723ff6df537 137
parthchandak02 0:b723ff6df537 138 FFT(vec, MAX, 1); //'d' should be 1 in order to have the same results of matlab fft(.)
parthchandak02 0:b723ff6df537 139 cout << "...printing the FFT of the array specified" << endl;
parthchandak02 1:b86b60ae81af 140 float absFFT = 0.0;
parthchandak02 0:b723ff6df537 141 for(int j = 0; j < MAX; j++)
parthchandak02 0:b723ff6df537 142 {
parthchandak02 1:b86b60ae81af 143 absFFT = 2*(std::abs(vec[j]))/MAX;
parthchandak02 1:b86b60ae81af 144 pc.printf("%f, %f\n", freqVector[j], absFFT); //Y: absFFT, X: freqVector
parthchandak02 0:b723ff6df537 145 }
parthchandak02 0:b723ff6df537 146
parthchandak02 0:b723ff6df537 147 return 0;
parthchandak02 0:b723ff6df537 148 }