rpitx/csdr
1
0
Fork 0
Code Issues Pull requests Packages Projects Releases Wiki Activity

Almost there at working interpolator

Browse source
This commit is contained in:
ha7ilm 2017-02-19 15:41:33 +01:00
parent 22ea31d5b1
commit 9ef8cd4b45
3 changed files with 29 additions and 15 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

17
csdr.c
View file

@ -48,6 +48,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "ima_adpcm.h"
#include <sched.h>
#include <math.h>
#include <assert.h>
char usage[]=
"csdr - a simple commandline tool for Software Defined Radio receiver DSP.\n\n"
@ -857,9 +858,11 @@ int main(int argc, char *argv[])
int factor;
sscanf(argv[2],"%d",&factor);
assert(factor >= 1);
float transition_bw = 0.05;
if(argc>=4) sscanf(argv[3],"%g",&transition_bw);
assert(transition_bw >= 0 && transition_bw < 1.);
window_t window = WINDOW_DEFAULT;
if(argc>=5)
@ -870,31 +873,33 @@ int main(int argc, char *argv[])
int taps_length=firdes_filter_len(transition_bw);
fprintf(stderr,"fir_interpolate_cc: taps_length = %d\n",taps_length);
assert(taps_length > 0);
while (env_csdr_fixed_big_bufsize < taps_length*2) env_csdr_fixed_big_bufsize*=2; //temporary fix for buffer size if [transition_bw] is low
//fprintf(stderr, "env_csdr_fixed_big_bufsize = %d\n", env_csdr_fixed_big_bufsize);
if(!initialize_buffers()) return -2;
sendbufsize(the_bufsize/factor);
sendbufsize(the_bufsize*factor);
assert(the_bufsize > 0);
float *taps;
taps=(float*)malloc(taps_length*sizeof(float));
assert(taps);
firdes_lowpass_f(taps,taps_length,0.5/(float)factor,window);
int input_skip=0;
int output_size=0;
FREAD_C;
float* interp_output_buffer = (float*)malloc(sizeof(float)*2*the_bufsize*factor);
for(;;)
{
FEOF_CHECK;
output_size=fir_interpolate_cc((complexf*)input_buffer, (complexf*)output_buffer, the_bufsize, factor, taps, taps_length);
output_size=fir_interpolate_cc((complexf*)input_buffer, (complexf*)interp_output_buffer, the_bufsize, factor, taps, taps_length);
//fprintf(stderr, "os %d\n",output_size);
fwrite(output_buffer, sizeof(complexf), output_size, stdout);
fwrite(interp_output_buffer, sizeof(complexf), output_size, stdout);
fflush(stdout);
TRY_YIELD;
input_skip=factor*output_size;
input_skip=output_size/factor;
memmove((complexf*)input_buffer,((complexf*)input_buffer)+input_skip,(the_bufsize-input_skip)*sizeof(complexf)); //memmove lets the source and destination overlap
fread(((complexf*)input_buffer)+(the_bufsize-input_skip), sizeof(complexf), input_skip, stdin);
//fprintf(stderr,"iskip=%d output_size=%d start=%x target=%x skipcount=%x \n",input_skip,output_size,input_buffer, ((complexf*)input_buffer)+(BIG_BUFSIZE-input_skip),(BIG_BUFSIZE-input_skip));

26
libcsdr.c
View file

@ -381,17 +381,25 @@ int fir_decimate_cc(complexf *input, complexf *output, int input_size, int decim
int fir_interpolate_cc(complexf *input, complexf *output, int input_size, int interpolation, float *taps, int taps_length)
{
//i: input index
//oi: output index
//ti: tap index
//ti: secondary index (inside filter function)
//ip: interpolation phase (0 <= ip < interpolation)
int oi=0;
for(int i=0; i<input_size*interpolation; i++) //@fir_decimate_cc: outer loop
for(int i=0; i<input_size; i++) //@fir_interpolate_cc: outer loop
{
if(i+taps_length>input_size) break;
float acci=0;
for(int ti=0; ti<taps_length; ti++) acci += (iof(input,i+ti)) * taps[ti]; //@fir_interpolate_cc: i loop
float accq=0;
for(int ti=0; ti<taps_length; ti++) accq += (qof(input,i+ti)) * taps[ti]; //@fir_interpolate_cc: q loop
iof(output,oi)=acci;
qof(output,oi)=accq;
oi++;
if(i*interpolation + (interpolation-1) + taps_length > input_size*interpolation) break;
for(int ip=0; ip<interpolation; ip++)
{
float acci=0;
float accq=0;
for(int ti=ip, si=0; ti<taps_length; ti+=interpolation, si++) acci += (iof(input,i+si)) * taps[ti]; //@fir_interpolate_cc: i loop
for(int ti=ip, si=0; ti<taps_length; ti+=interpolation, si++) accq += (qof(input,i+si)) * taps[ti]; //@fir_interpolate_cc: q loop
iof(output,oi)=acci;
qof(output,oi)=accq;
oi++;
}
}
return oi;
}

1
libcsdr.h
View file

@ -99,6 +99,7 @@ void limit_ff(float* input, float* output, int input_size, float max_amplitude);
//filters, decimators, resamplers, shift, etc.
float fir_one_pass_ff(float* input, float* taps, int taps_length);
int fir_decimate_cc(complexf *input, complexf *output, int input_size, int decimation, float *taps, int taps_length);
int fir_interpolate_cc(complexf *input, complexf *output, int input_size, int interpolation, float *taps, int taps_length);
int deemphasis_nfm_ff (float* input, float* output, int input_size, int sample_rate);
float deemphasis_wfm_ff (float* input, float* output, int input_size, float tau, int sample_rate, float last_output);
float shift_math_cc(complexf *input, complexf* output, int input_size, float rate, float starting_phase);