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authorArturs Artamonovs <arturs.artamonovs@protonmail.com>2021-08-11 07:24:29 +0100
committerArturs Artamonovs <arturs.artamonovs@protonmail.com>2021-08-11 07:24:29 +0100
commitf21c09ccf01ed230c1fe7e388a6208432251cbf1 (patch)
treec510505f41167c1ad4d3503a2951da491218988a
parentdd527f05895d4984170f2174ca09166ef9d883fc (diff)
downloadNaiveFFT-f21c09ccf01ed230c1fe7e388a6208432251cbf1.tar.gz
NaiveFFT-f21c09ccf01ed230c1fe7e388a6208432251cbf1.zip
working dft
-rw-r--r--NaiveFFT/main.c186
1 files changed, 185 insertions, 1 deletions
diff --git a/NaiveFFT/main.c b/NaiveFFT/main.c
index c43c48b..fec893b 100644
--- a/NaiveFFT/main.c
+++ b/NaiveFFT/main.c
@@ -6,9 +6,193 @@
//
#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <math.h>
+#include <complex.h>
+
+//data array
+#define DATA_SIZE (8)
+double data_i[DATA_SIZE] = {1.0f,0.0f,0.0f,0.0f,0.0f,0.0f,0.0f,0.0f};
+double data_q[DATA_SIZE] = {0.0f,0.0f,0.0f,0.0f,0.0f,0.0f,0.0f,0.0f};
+//calc the fft
+void fft_if(double *x_i, double *x_q, int n, int inv) {
+
+ int i=0,j=0,k=0,m=0, irem=0, sign;
+ double tq,ti;
+
+ printf("FFT\n");
+ k=n/2;
+ for (j=1,i=1;i<n; i++) {
+ if (i<j) {
+
+ //swap values
+ ti = x_i[j];
+ tq = x_q[j];
+
+ x_i[j] = x_i[i];
+ x_q[j] = x_q[i];
+
+ x_i[i] = ti;
+ x_q[i] = tq;
+ printf("i=%d j=%d\n",i,j);
+ //find middle point
+ k = n/2;
+ while (k<j) {
+ j = j-k;
+ k=k/2;
+ }
+ } else {
+ printf("i=%d j=%d\n",i,j);
+ k = n/2;
+ while (k<j) {
+ j = j - k;
+ k = k/2;
+ }
+ }
+ j = j+k;
+ }
+
+ for (i=0;i<DATA_SIZE;i++) {
+ printf("%.2f ",x_i[i]);
+ }
+ printf("\n");
+ for (i=0;i<DATA_SIZE;i++) {
+ printf("%.2f ",x_q[i]);
+ }
+ printf("\n");
+
+ //calculate number of stages:
+ //m=log2(n)
+ m=0;
+ irem = n;
+ while(irem>1) {
+ irem = irem/2;
+ m = m+1;
+ }
+
+
+ //FFT or IFFT
+ if (inv==1) {
+ sign = 1;
+ } else {
+ sign = -1;
+ }
+
+ // transform
+ for (i=0; i<m; i++) {
+ int le=pow(2,i);
+ int le1=le/2;
+ double ui=1.0;
+ double uq=0.0;
+ double wi = cos(M_PI/le1);
+ double wq = sign*sin(M_PI/le1);
+
+ for (j=1; j<le1;j++) {
+ i=j;
+ while (i<n) {
+ int ip = i+le1;
+
+ ti = x_i[ip]*ui - x_q[ip]*uq;
+ tq = x_q[ip]*ui + x_i[ip]*uq;
+
+ x_i[ip] = x_i[i] - ti;
+ x_q[ip] = x_q[i] - tq;
+
+ x_i[i] = x_i[i] + ti;
+ x_q[i] = x_q[i] + tq;
+
+ i = i+le;
+ }
+ double temp = ui*wi - uq*wq;
+ uq = uq*wi + ui*wq;
+ ui = temp;
+ }
+ }
+
+ //if inverse
+ if (inv==1) {
+ for (i=0;i<n;i++) {
+ x_i[i] = x_i[i]/n;
+ x_q[i] = x_q[i]/n;
+ }
+ }
+
+}
+
+//dft works fine
+void dft(double *x_i, double *x_q, int n, int inv) {
+ double Wn,Wk;
+ //static array
+ //double Xi[DATA_SIZE],Xq[DATA_SIZE];
+ //dynamic array
+ double *Xi, *Xq;
+ double c,s;
+ int i,j;
+
+ Xi = malloc(n*sizeof(double));
+ Xq = malloc(n*sizeof(double));
+
+ Wn = 2*M_PI/n;
+
+ if (inv==1) {
+ Wn=-Wn;
+ }
+
+ for (i=0;i<n;i++) {
+ Xi[i] = 0.0f;
+ Xq[i] = 0.0f;
+
+ Wk = i*Wn;
+ for (j=0;j<n;j++) {
+ c = cos(j*Wk);
+ s = sin(j*Wk);
+
+ //i - real, q - imaginary
+ Xi[i] = Xi[i] + x_i[j]*c + x_q[j]*s;
+ Xq[i] = Xq[i] - x_i[j]*s + x_q[j]*c;
+ }
+
+ if (inv==1) {
+ Xi[i] = Xi[i]/n;
+ Xq[i] = Xq[i]/n;
+ }
+ }
+
+ for (i=0;i<n;i++) {
+ x_i[i] = Xi[i];
+ x_q[i] = Xq[i];
+ }
+
+}
int main(int argc, const char * argv[]) {
+ int i;
+
// insert code here...
- printf("Hello, World!\n");
+ printf("Hello FFT World!\n");
+
+ for (i=0;i<DATA_SIZE;i++) {
+ printf("%.2f ",data_i[i]);
+ }
+ printf("\n");
+ for (i=0;i<DATA_SIZE;i++) {
+ printf("%.2f ",data_q[i]);
+ }
+ printf("\n");
+ fft_if(data_i, data_q, DATA_SIZE, 0);
+
+ //dft(data_i, data_q, DATA_SIZE,0);
+
+ for (i=0;i<DATA_SIZE;i++) {
+ printf("%.2f ",data_i[i]);
+ }
+ printf("\n");
+ for (i=0;i<DATA_SIZE;i++) {
+ printf("%.2f ",data_q[i]);
+ }
+ printf("\n");
+
return 0;
}