qi-hardware/ben-wpan
1
0
Fork 0
mirror of git://projects.qi-hardware.com/ben-wpan.git synced 2024-11-17 21:09:21 +02:00
Code

usrp: support DCT in addition to complex FFT

Browse Source 
- usrp/evscan (usage, main): treat all arguments but the last as options
  and pass them to "fft"
- usrp/fft.c (fft_complex, do_fft): moved actual FFT calculation to
  separate function
- usrp/fft.c (fft_real, do_fft): added real-valued FFT (DCT) as alternative
- usrp/fft.c (main): undocumented option -a to set the FFT algorithm
This commit is contained in:
Werner Almesberger 2010-11-26 12:16:34 -03:00
parent 59beaba426
commit 83d216244c
2 changed files with 79 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
usrp/evscan
View File

@ -2,17 +2,22 @@
usage()
{
echo "usage: $0 base-dir" 1>&2
echo "usage: $0 [options] base-dir" 1>&2
exit 1
}
[ "$1" ] || usage
opts=
while [ "$2" ]; do
opts="$opts $1"
shift
done
[ -d "$1" ] || usage
[ "$2" ] && usage
for f in "$1"/24*; do
echo -n `basename "$f"` ''
for n in "$f"/data*; do
./fft -s 100 0 20 50 <"$n" || echo "fft failed for $n" 1>&1
./fft $opts -s 100 0 20 50 <"$n" || echo "fft failed for $n" 1>&1
done | ./range -v 2
done

89
usrp/fft.c
View File

@ -9,13 +9,61 @@
#define DEFAULT_THRESHOLD 100
static int alg = 0;
static void fft_complex(int n, const float *re, const float *im, double *res)
{
fftw_complex *in, *out;
fftw_plan plan;
int i;
double a;
in = fftw_malloc(sizeof(fftw_complex)*n);
out = fftw_malloc(sizeof(fftw_complex)*n);
for (i = 0; i != n; i++) {
in[i][0] = re[i];
in[i][1] = im[i];
}
plan = fftw_plan_dft_1d(n, in, out, FFTW_FORWARD, FFTW_ESTIMATE);
fftw_execute(plan);
for (i = 0; i != n; i++) {
a = hypot(out[i][0], out[i][1])/n;
a = a*a;
res[i] = a;
}
}
static void fft_real(int n, const float *re, const float *im, double *res)
{
double *in;
fftw_plan plan;
int i;
double a ;
in = fftw_malloc(sizeof(double)*n);
(void) a;
for (i = 0; i != n; i++)
in[i] = hypot(re[i], im[i]);
plan = fftw_plan_r2r_1d(n, in, res, FFTW_REDFT10, FFTW_ESTIMATE);
fftw_execute(plan);
for (i = 0; i != n; i++)
res[i] /= n;
}
static void do_fft(int skip, int dump, int low, int high, double threshold)
{
float c[2];
float *re = NULL, *im = NULL;
fftw_complex *in, *out;
fftw_plan plan;
double *res;
int e = 0, n = 0;
int i;
double a;
@ -58,23 +106,26 @@ static void do_fft(int skip, int dump, int low, int high, double threshold)
im += skip;
n -= skip;
in = fftw_malloc(sizeof(fftw_complex)*n);
out = fftw_malloc(sizeof(fftw_complex)*n);
for (i = 0; i != n; i++) {
in[i][0] = re[i];
in[i][1] = im[i];
res = malloc(n*sizeof(double));
if (!res) {
perror("malloc");
exit(1);
}
plan = fftw_plan_dft_1d(n, in, out, FFTW_FORWARD, FFTW_ESTIMATE);
fftw_execute(plan);
switch (alg) {
case 0:
fft_complex(n, re, im, res);
break;
case 1:
fft_real(n, re, im, res);
break;
default:
abort();
}
if (dump) {
for (i = 0; i < n; i += 1) {
a = hypot(out[i][0], out[i][1])/n;
// a = a*a;
printf("%d %g\n", i, 10*log(a)/log(10));
}
for (i = 0; i < n; i += 1)
printf("%d %g\n", i, 10*log(res[i])/log(10));
} else {
double s = 0;
double db;
@ -91,8 +142,7 @@ static void do_fft(int skip, int dump, int low, int high, double threshold)
if (low == high)
low--;
for (i = low; i != high; i++) {
a = hypot(out[i][0], out[i][1])/n;
// a = a*a;
a = res[i];
db = 10*log(a)/log(10);
if (db >= threshold)
s += a;
@ -124,8 +174,11 @@ int main(int argc, char **argv)
double threshold = DEFAULT_THRESHOLD;
int c;
while ((c = getopt(argc, argv, "ds:")) != EOF)
while ((c = getopt(argc, argv, "a:ds:")) != EOF)
switch (c) {
case 'a':
alg = atoi(optarg);
break;
case 'd':
dump = 1;
break;