kopia lustrzana https://github.com/rs1729/RS
174 wiersze
4.4 KiB
C
174 wiersze
4.4 KiB
C
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#include <stdio.h>
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#include <string.h>
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#include "rs_data.h"
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#include "rs_demod.h"
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static int sample_rate = 0,
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bits_sample = 0,
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channels = 0;
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static float samples_per_bit = 0.0;
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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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int read_wav_header(FILE *fp, rs_data_t *rs_data) {
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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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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); // string.h
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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)) return -1;
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samples_per_bit = sample_rate/rs_data->baud;
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fprintf(stderr, "samples/bit: %.2f\n", samples_per_bit);
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rs_data->samples_per_bit = samples_per_bit;
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return 0;
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}
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#define EOF_INT 0x1000000
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static unsigned long sample_count = 0;
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static int read_signed_sample(FILE *fp) { // int = i32_t
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int byte, i, sample, s=0; // EOF -> 0x1000000
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for (i = 0; i < channels; i++) {
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// i = 0: left/mono
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byte = fgetc(fp);
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if (byte == EOF) return EOF_INT;
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if (i == 0) sample = byte;
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if (bits_sample == 16) {
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byte = fgetc(fp);
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if (byte == EOF) return EOF_INT;
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if (i == 0) sample += byte << 8;
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}
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}
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if (bits_sample == 8) s = sample-128; // 8bit: 00..FF, centerpoint 0x80=128
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if (bits_sample == 16) s = (short)sample;
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sample_count++;
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return s;
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}
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static int par=1, par_alt=1;
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int read_bits_fsk(FILE *fp, int *bit, int *len, int inv) {
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int option_res = 0;
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static int sample;
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int n, y0;
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float l, x1;
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static float x0;
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n = 0;
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do{
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y0 = sample;
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sample = read_signed_sample(fp);
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if (sample == EOF_INT) return EOF;
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//sample_count++; // in read_signed_sample()
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par_alt = par;
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par = (sample >= 0) ? 1 : -1; // 8bit: 0..127,128..255 (-128..-1,0..127)
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n++;
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} while (par*par_alt > 0);
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if (!option_res) l = (float)n / samples_per_bit;
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else { // genauere Bitlaengen-Messung
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x1 = sample/(float)(sample-y0); // hilft bei niedriger sample rate
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l = (n+x0-x1) / samples_per_bit; // meist mehr frames (nicht immer)
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x0 = x1;
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}
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*len = (int)(l+0.5);
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if (!inv) *bit = (1+par_alt)/2; // oben 1, unten -1
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else *bit = (1-par_alt)/2; // sdr#<rev1381?, invers: unten 1, oben -1
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/* Y-offset ? */
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return 0;
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}
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/* ------------------------------------------------------------------------------------ */
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void inc_bufpos(rs_data_t *rs_data) {
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rs_data->bufpos = (rs_data->bufpos+1) % rs_data->header_len;
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}
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int compare(rs_data_t *rs_data) {
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int i=0, j = rs_data->bufpos;
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while (i < rs_data->header_len) {
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if (j < 0) j = rs_data->header_len-1;
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if (rs_data->buf[j] != rs_data->header[rs_data->header_ofs+rs_data->header_len-1-i]) break;
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j--;
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i++;
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}
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return i;
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}
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/* ------------------------------------------------------------------------------------ */
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