kopia lustrzana https://github.com/rs1729/RS
465 wiersze
11 KiB
C
465 wiersze
11 KiB
C
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/*
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* compile:
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* gcc -Ofast iq_fm.c -lm -o iq_fm
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*
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* usage:
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* ./iq_fm [--lpbw <lp>] [- <sr> <bps>] [--bo <bps_out> [--wav] [iqfile]
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* --lpbw <lp> : lowpass bw in kHz, default 12.0
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* - <sr> <bps> : input raw IQ data
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* --bo <bps_out> : bps=8,16,32 output bps
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* --wav : output wav header
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* [iqfile] : wav IQ-file or raw data (no iqfile: stdin)
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*
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* examples:
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* ./iq_fm --lpbw 8.0 - 48000 16 --wav iq_data_48k16.raw > fm.wav
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* cat iq_data_48k32.raw | ./iq_fm --lpbw 8.0 - 48000 32 > fm_48k32.raw
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* ./iq_fm --lpbw 8.0 --wav iq_data.wav > fm.wav
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*
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* author: zilog80
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#include <complex.h>
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#ifndef M_PI
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#define M_PI (3.1415926535897932384626433832795)
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#endif
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#define FM_GAIN (0.8)
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typedef unsigned char ui8_t;
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typedef unsigned short ui16_t;
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typedef unsigned int ui32_t;
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typedef char i8_t;
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typedef short i16_t;
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typedef int i32_t;
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typedef struct {
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FILE *fp;
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//
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int sr; // sample_rate
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int bps; // bits/sample
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int nch; // channels
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int bps_out;
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ui32_t sample;
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// IF: lowpass
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int lpIQ_bw;
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float lpIQ_fbw;
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int lpIQtaps;
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float *ws_lpIQ;
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float complex *lpIQ_buf;
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} dsp_t;
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typedef struct {
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int sr; // sample_rate
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int bps; // bits_sample bits/sample
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int nch; // channels
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int bps_out;
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FILE *fp;
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} pcm_t;
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static int findstr(char *buff, char *str, int pos) {
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int i;
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for (i = 0; i < 4; i++) {
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if (buff[(pos+i)%4] != str[i]) break;
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}
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return i;
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}
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static float read_wav_header(pcm_t *pcm) {
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FILE *fp = pcm->fp;
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char txt[4+1] = "\0\0\0\0";
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unsigned char dat[4];
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int byte, p=0;
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int sample_rate = 0, bits_sample = 0, channels = 0;
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if (fread(txt, 1, 4, fp) < 4) return -1;
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if (strncmp(txt, "RIFF", 4)) return -1;
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if (fread(txt, 1, 4, fp) < 4) return -1;
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// pos_WAVE = 8L
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if (fread(txt, 1, 4, fp) < 4) return -1;
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if (strncmp(txt, "WAVE", 4)) return -1;
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// pos_fmt = 12L
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for ( ; ; ) {
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if ( (byte=fgetc(fp)) == EOF ) return -1;
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txt[p % 4] = byte;
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p++; if (p==4) p=0;
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if (findstr(txt, "fmt ", p) == 4) break;
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}
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if (fread(dat, 1, 4, fp) < 4) return -1;
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if (fread(dat, 1, 2, fp) < 2) return -1;
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if (fread(dat, 1, 2, fp) < 2) return -1;
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channels = dat[0] + (dat[1] << 8);
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if (fread(dat, 1, 4, fp) < 4) return -1;
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memcpy(&sample_rate, dat, 4); //sample_rate = dat[0]|(dat[1]<<8)|(dat[2]<<16)|(dat[3]<<24);
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if (fread(dat, 1, 4, fp) < 4) return -1;
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if (fread(dat, 1, 2, fp) < 2) return -1;
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//byte = dat[0] + (dat[1] << 8);
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if (fread(dat, 1, 2, fp) < 2) return -1;
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bits_sample = dat[0] + (dat[1] << 8);
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// pos_dat = 36L + info
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for ( ; ; ) {
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if ( (byte=fgetc(fp)) == EOF ) return -1;
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txt[p % 4] = byte;
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p++; if (p==4) p=0;
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if (findstr(txt, "data", p) == 4) break;
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}
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if (fread(dat, 1, 4, fp) < 4) return -1;
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fprintf(stderr, "sample_rate: %d\n", sample_rate);
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fprintf(stderr, "bits : %d\n", bits_sample);
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fprintf(stderr, "channels : %d\n", channels);
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if (bits_sample != 8 && bits_sample != 16 && bits_sample != 32) return -1;
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pcm->sr = sample_rate;
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pcm->bps = bits_sample;
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pcm->nch = channels;
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return 0;
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}
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static float write_wav_header(pcm_t *pcm) {
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FILE *fp = stdout;
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ui32_t sr = pcm->sr;
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ui32_t bps = pcm->bps_out;
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ui32_t data = 0;
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fwrite("RIFF", 1, 4, fp);
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data = 0; // bytes-8=headersize-8+datasize
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fwrite(&data, 1, 4, fp);
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fwrite("WAVE", 1, 4, fp);
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fwrite("fmt ", 1, 4, fp);
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data = 16; if (bps == 32) data += 2;
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fwrite(&data, 1, 4, fp);
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if (bps == 32) data = 3; // IEEE float
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else data = 1; // PCM
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fwrite(&data, 1, 2, fp);
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data = 1; // 1 channel
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fwrite(&data, 1, 2, fp);
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data = sr;
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fwrite(&data, 1, 4, fp);
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data = sr*bps/8;
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fwrite(&data, 1, 4, fp);
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data = (bps+7)/8;
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fwrite(&data, 1, 2, fp);
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data = bps;
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fwrite(&data, 1, 2, fp);
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if (bps == 32) {
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data = 0; // size of extension: 0
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fwrite(&data, 1, 2, fp);
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}
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fwrite("data", 1, 4, fp);
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data = 0; // datasize
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fwrite(&data, 1, 4, fp);
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return 0;
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}
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static int f32read_csample(dsp_t *dsp, float complex *z) {
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float x, y;
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if (dsp->bps == 32) { //float32
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float f[2];
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if (fread( f, dsp->bps/8, 2, dsp->fp) != 2) return EOF;
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x = f[0];
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y = f[1];
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}
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else if (dsp->bps == 16) { //int16
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short b[2];
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if (fread( b, dsp->bps/8, 2, dsp->fp) != 2) return EOF;
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x = b[0]/32768.0;
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y = b[1]/32768.0;
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}
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else { // dsp->bps == 8 //uint8
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ui8_t u[2];
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if (fread( u, dsp->bps/8, 2, dsp->fp) != 2) return EOF;
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x = (u[0]-128)/128.0;
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y = (u[1]-128)/128.0;
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}
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*z = x + I*y;
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return 0;
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}
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static double sinc(double x) {
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double y;
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if (x == 0) y = 1;
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else y = sin(M_PI*x)/(M_PI*x);
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return y;
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}
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static int lowpass_init(float f, int taps, float **pws) {
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double *h, *w;
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double norm = 0;
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int n;
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float *ws = NULL;
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if (taps % 2 == 0) taps++; // odd/symmetric
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if ( taps < 1 ) taps = 1;
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h = (double*)calloc( taps+1, sizeof(double)); if (h == NULL) return -1;
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w = (double*)calloc( taps+1, sizeof(double)); if (w == NULL) return -1;
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ws = (float*)calloc( 2*taps+1, sizeof(float)); if (ws == NULL) return -1;
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for (n = 0; n < taps; n++) {
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w[n] = 7938/18608.0 - 9240/18608.0*cos(2*M_PI*n/(taps-1)) + 1430/18608.0*cos(4*M_PI*n/(taps-1)); // Blackmann
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h[n] = 2*f*sinc(2*f*(n-(taps-1)/2));
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ws[n] = w[n]*h[n];
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norm += ws[n]; // 1-norm
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}
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for (n = 0; n < taps; n++) {
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ws[n] /= norm; // 1-norm
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}
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for (n = 0; n < taps; n++) ws[taps+n] = ws[n]; // duplicate/unwrap
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*pws = ws;
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free(h); h = NULL;
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free(w); w = NULL;
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return taps;
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}
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static float complex lowpass0(float complex buffer[], ui32_t sample, ui32_t taps, float *ws) {
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ui32_t n;
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double complex w = 0;
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for (n = 0; n < taps; n++) {
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w += buffer[(sample+n+1)%taps]*ws[taps-1-n];
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}
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return (float complex)w;
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}
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static float complex lowpass(float complex buffer[], ui32_t sample, ui32_t taps, float *ws) {
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ui32_t n;
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ui32_t s = sample % taps;
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double complex w = 0;
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for (n = 0; n < taps; n++) {
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w += buffer[n]*ws[taps+s-n]; // ws[taps+s-n] = ws[(taps+sample-n)%taps]
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}
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return (float complex)w;
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// symmetry: ws[n] == ws[taps-1-n]
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}
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/* -------------------------------------------------------------------------- */
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#define IF_TRANSITION_BW (4e3) // 4kHz transition width
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static int init_buffers(dsp_t *dsp) {
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float f_lp; // lowpass_bw
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int taps; // lowpass taps: 4*sr/transition_bw
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// IF lowpass
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f_lp = 24e3; // default
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f_lp = dsp->lpIQ_bw/(float)dsp->sr/2.0;
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taps = 4*dsp->sr/IF_TRANSITION_BW; if (taps%2==0) taps++;
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taps = lowpass_init(f_lp, taps, &dsp->ws_lpIQ); if (taps < 0) return -1;
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dsp->lpIQ_fbw = f_lp;
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dsp->lpIQtaps = taps;
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dsp->lpIQ_buf = calloc( dsp->lpIQtaps+3, sizeof(float complex));
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if (dsp->lpIQ_buf == NULL) return -1;
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return 0;
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}
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static int free_buffers(dsp_t *dsp) {
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if (dsp->lpIQ_buf) { free(dsp->lpIQ_buf); dsp->lpIQ_buf = NULL; }
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if (dsp->ws_lpIQ) { free(dsp->ws_lpIQ); dsp->ws_lpIQ = NULL; }
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return 0;
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}
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/* -------------------------------------------------------------------------- */
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static int fm_demod(dsp_t *dsp, float *s) {
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double gain = FM_GAIN;
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float complex z, z1, w;
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static float complex z0;
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if ( f32read_csample(dsp, &z) == EOF ) return EOF;
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dsp->lpIQ_buf[dsp->sample % dsp->lpIQtaps] = z;
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z1 = lowpass(dsp->lpIQ_buf, dsp->sample, dsp->lpIQtaps, dsp->ws_lpIQ);
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w = z1 * conj(z0);
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*s = gain * carg(w)/M_PI;
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z0 = z1;
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dsp->sample += 1;
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return 0;
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}
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static int write_fm(dsp_t *dsp, float s) {
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int bps = dsp->bps_out;
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FILE *fpo = stdout;
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ui8_t u = 0;
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i16_t b = 0;
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ui32_t *w = (ui32_t*)&s;
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if (bps == 8) {
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s *= 127.0;
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s += 128.0;
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u = (ui8_t)s;
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w = (ui32_t*)&u;
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}
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else if (bps == 16) {
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s *= 127.0*256.0;
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b = (i16_t)s;
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w = (ui32_t*)&b;
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}
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fwrite( w, bps/8, 1, fpo);
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return 0;
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}
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int main(int argc, char *argv[]) {
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int k;
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int option_pcmraw = 0;
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int option_wav = 0;
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int file_loaded = 0;
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int bitQ = 0;
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float lpIQ_bw = 12e3;
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float s = 0.0;
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FILE *fp;
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pcm_t pcm = {0};
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dsp_t dsp = {0};
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++argv;
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while ((*argv) && (!file_loaded)) {
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if (0) { }
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else if (strcmp(*argv, "--lpbw") == 0) { // IQ lowpass BW / kHz
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double bw = 0.0;
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++argv;
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if (*argv) bw = atof(*argv);
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else return 1;
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if (bw > 4.6 && bw < 24.0) lpIQ_bw = bw*1e3;
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}
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else if (strcmp(*argv, "-") == 0) {
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int sample_rate = 0, bits_sample = 0, channels = 0;
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++argv;
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if (*argv) sample_rate = atoi(*argv); else return 1;
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++argv;
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if (*argv) bits_sample = atoi(*argv); else return 1;
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channels = 2;
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if (sample_rate < 1 || (bits_sample != 8 && bits_sample != 16 && bits_sample != 32)) {
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fprintf(stderr, "- <sr> <bs>\n");
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return 1;
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}
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pcm.sr = sample_rate;
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pcm.bps = bits_sample;
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pcm.nch = channels;
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option_pcmraw = 1;
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}
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else if (strcmp(*argv, "--bo") == 0) {
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int bps_out = 0;
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++argv;
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if (*argv) bps_out = atoi(*argv); else return 1;
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if ((bps_out != 8 && bps_out != 16 && bps_out != 32)) {
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bps_out = 0;
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}
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pcm.bps_out = bps_out;
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}
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else if (strcmp(*argv, "--wav") == 0) {
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option_wav = 1;
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}
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else {
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fp = fopen(*argv, "rb");
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if (fp == NULL) {
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fprintf(stderr, "error: open %s\n", *argv);
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return 1;
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}
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file_loaded = 1;
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}
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++argv;
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}
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if (!file_loaded) fp = stdin;
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pcm.fp = fp;
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if (option_pcmraw == 0) {
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k = read_wav_header( &pcm );
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if ( k < 0 ) {
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fclose(fp);
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fprintf(stderr, "error: wav header\n");
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return 1;
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}
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}
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if (pcm.nch < 2) {
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fprintf(stderr, "error: iq channels < 2\n");
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return 1;
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}
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if (pcm.bps_out == 0) pcm.bps_out = pcm.bps;
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if (option_wav) write_wav_header( &pcm );
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dsp.fp = fp;
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dsp.sr = pcm.sr;
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dsp.bps = pcm.bps;
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dsp.nch = pcm.nch;
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dsp.bps_out = pcm.bps_out;
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dsp.lpIQ_bw = lpIQ_bw; // IF lowpass bandwidth
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init_buffers(&dsp);
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while ( 1 )
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{
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bitQ = fm_demod(&dsp, &s);
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if ( bitQ == EOF ) break;
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write_fm(&dsp, s);
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}
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free_buffers(&dsp);
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return 0;
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}
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