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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <math.h>
//radiola
#include <hw/hw.h>
#include <hw/sdr.h>
#define SAMPLE_RATE 2048000
#define CENTER_FREQ 446018750
#define FFT_LEVEL 10
#define FFT_SIZE (1 << FFT_LEVEL)
#define SAMPLE_LENGHT (2 * FFT_SIZE)
#define PRESCALE 8
#define POSTSCALE 2
#define WIDTH_POINTS 32
int16_t* Sinewave;
int N_WAVE, LOG2_N_WAVE;
double* power_table;
//better to have size size mod olen == 0
int normalise( uint8_t *ibuf, int ilen, uint8_t *obuf, int olen )
{
uint32_t i,j,m;
uint32_t ppi;
uint32_t sum;
div_t d;
if ( ilen >= olen )
{
d = div(ilen,olen);
ppi = d.quot;
if (d.rem > 0)
ppi += 1;
} else {
printf("Input buffer smaller ther output buffer\n");
return -1;
}
m = 0;
i = 0;
for (i=0,m=0; i < ilen+ppi; i += ppi, m++)
{
sum = 0;
for (j=0;j<ppi;j++)
sum += ibuf[i+j];
obuf[m] = sum/ppi;
}
return 0;
}
void sine_table(int size)
{
int i;
double d;
LOG2_N_WAVE = size;
N_WAVE = 1 << LOG2_N_WAVE;
Sinewave = malloc(sizeof(int16_t) * N_WAVE*3/4);
power_table = malloc(sizeof(double) * N_WAVE);
for (i=0; i<N_WAVE*3/4; i++)
{
d = (double)i * 2.0 * M_PI / N_WAVE;
Sinewave[i] = (int)round(32767*sin(d));
}
}
int16_t FIX_MPY(int16_t a, int16_t b)
/* fixed point multiply and scale */
{
int c = ((int)a * (int)b) >> 14;
b = c & 0x01;
return (c >> 1) + b;
}
int32_t real_conj(int16_t real, int16_t imag)
/* real(n * conj(n)) */
{
return ((int32_t)real*(int32_t)real + (int32_t)imag*(int32_t)imag);
}
int fix_fft(int16_t iq[], int m)
/* interleaved iq[], 0 <= n < 2**m, changes in place */
{
int mr, nn, i, j, l, k, istep, n, shift;
int16_t qr, qi, tr, ti, wr, wi;
n = 1 << m;
if (n > N_WAVE)
{return -1;}
mr = 0;
nn = n - 1;
/* decimation in time - re-order data */
for (m=1; m<=nn; ++m) {
l = n;
do
{l >>= 1;}
while (mr+l > nn);
mr = (mr & (l-1)) + l;
if (mr <= m)
{continue;}
// real = 2*m, imag = 2*m+1
tr = iq[2*m];
iq[2*m] = iq[2*mr];
iq[2*mr] = tr;
ti = iq[2*m+1];
iq[2*m+1] = iq[2*mr+1];
iq[2*mr+1] = ti;
}
l = 1;
k = LOG2_N_WAVE-1;
while (l < n) {
shift = 1;
istep = l << 1;
for (m=0; m<l; ++m) {
j = m << k;
wr = Sinewave[j+N_WAVE/4];
wi = -Sinewave[j];
if (shift) {
wr >>= 1; wi >>= 1;}
for (i=m; i<n; i+=istep) {
j = i + l;
tr = FIX_MPY(wr,iq[2*j]) - FIX_MPY(wi,iq[2*j+1]);
ti = FIX_MPY(wr,iq[2*j+1]) + FIX_MPY(wi,iq[2*j]);
qr = iq[2*i];
qi = iq[2*i+1];
if (shift) {
qr >>= 1; qi >>= 1;}
iq[2*j] = qr - tr;
iq[2*j+1] = qi - ti;
iq[2*i] = qr + tr;
iq[2*i+1] = qi + ti;
}
}
--k;
l = istep;
}
return 0;
}
//fftize
int simple_fft( uint8_t *buf, int len )
{
int i,j;
uint16_t p;
uint16_t buf1[SAMPLE_LENGHT];
uint16_t buf2[SAMPLE_LENGHT];
int fft_len;
for (i=0; i<len; i++)
{
buf1[i] = buf[i] * PRESCALE;
}
fix_fft( (uint16_t *)buf1, FFT_LEVEL );
for (i=0; i<FFT_SIZE; i+=1)
{
//buf1[i] = rtl_out.buf[i];
//p = buf1[i] * buf1[i];
j = i*2;
p = (int16_t)real_conj(buf1[j], buf1[j + 1]);
buf2[i] = p;
}
fft_len = FFT_SIZE / 2;
for (i=0; i<fft_len; i++)
{
buf[i] = (int)log10(POSTSCALE * (float)buf2[i+fft_len]);
buf[i+fft_len] = (int)log10(POSTSCALE * (float)buf2[i]);
}
return 0;
}
int pipe_watefall( int size, uint8_t *buf )
{
int i;
for (i=0;i<size;i++)
{
printf("%02d",(unsigned char)buf[i]);
if (i!=size-1) printf(",");
}
printf("\n");
return 0;
}
int main()
{
int i,j;
uint8_t *buf, *sample_buf;
int buf_len, sample_len;
uint32_t dev_num;
sdr_t *sdr = NULL;
dongle_t *dongle = NULL;
if ( (sdr = sdr_init()) == NULL )
{
printf("Cannot init sdr manager\n");
goto main_exit;
}
if ( sdr_open_device( sdr, 0 ) != 0 )
{
printf("Cannot open dongle 0\n");
goto main_exit;
}
dongle = sdr_get_device_id( sdr, 0 );
dongle_set_freq( dongle, CENTER_FREQ );
dongle_set_sample_rate( dongle, SAMPLE_RATE );
sine_table( FFT_LEVEL );
buf_len = WIDTH_POINTS;
buf = malloc( buf_len );
sample_len = SAMPLE_LENGHT;
sample_buf = malloc( sample_len );
srand(0); //fake seed
for ( i=0; i<40;i++ )
{
//read some samples
dongle_read_samples( dongle, sample_buf, sample_len );
//do fft
simple_fft( sample_buf, sample_len );
//prepare to show on the screen
if (normalise( sample_buf, sample_len/2, buf, buf_len ) == -1)
{
printf("Cannot normalise\n");
}
pipe_watefall( buf_len, buf );
usleep(1000000);
}
main_exit:
//close gui, restore terminal mode
sdr_close( sdr );
return 0;
}
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