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dstar.c
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dstar.c
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/*
* Copyright (C) 2010 DSD Author
* GPG Key ID: 0x3F1D7FD0 (74EF 430D F7F2 0A48 FCE6 F630 FAA2 635D 3F1D 7FD0)
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
/*
* Note: D-STAR support is fairly complete at this point.
* The ambe3600x2450 decoder is similar butnot compatible with D-STAR voice frames.
* The dstar interleave pattern is different as well.
* GMSK modulation optimizations will also required to get a usable bit error
*/
#include "dsd.h"
#include "dstar_const.h"
#include "descramble.h"
unsigned int processDSTAR(dsd_opts * opts, dsd_state * state) {
// extracts AMBE frames from D-STAR voice frame
int i, j, dibit;
char ambe_fr[4][24];
unsigned int total_errs = 0, sync_missed = 0, framecount;
unsigned char slowdata[4];
unsigned int bitbuffer = 0;
const unsigned char *w, *x;
if (state->synctype == 18) {
framecount = 0;
state->synctype = 6;
} else if (state->synctype == 19) {
framecount = 0;
state->synctype = 7;
} else {
framecount = 1; //just saw a sync frame; there should be 20 not 21 till the next
}
while (sync_missed < 3) {
for (i = 0; i < 24; i++) {
ambe_fr[0][i] = ambe_fr[1][i] = ambe_fr[2][i] = ambe_fr[3][i] = 0;
}
// voice frame
w = dW;
x = dX;
for (i = 0; i < 72; i++) {
dibit = getDibit(opts, state);
bitbuffer <<= 1;
if (dibit == 1) {
bitbuffer |= 0x01;
}
if ((bitbuffer & 0x00FFFFFF) == 0x00AAB468) {
// we're slipping bits
printf("sync in voice after i=%u, restarting\n", i);
//ugh just start over
i = 0;
w = dW;
x = dX;
framecount = 1;
continue;
}
ambe_fr[*w++][*x++] = (1 & dibit);
}
processAMBEFrame(opts, state, ambe_fr);
total_errs += state->errs2;
// data frame - 24 bits
for (i = 73; i < 97; i++) {
dibit = getDibit(opts, state);
bitbuffer <<= 1;
if (dibit == 1) {
bitbuffer |= 0x01;
}
if ((bitbuffer & 0x00FFFFFF) == 0x00AAB468) {
// looking if we're slipping bits
if (i != 96) {
printf("sync after i=%d\n", i);
i = 96;
}
}
}
slowdata[0] = (bitbuffer >> 16) & 0x000000FF;
slowdata[1] = (bitbuffer >> 8) & 0x000000FF;
slowdata[2] = (bitbuffer) & 0x000000FF;
slowdata[3] = 0;
if ((bitbuffer & 0x00FFFFFF) == 0x00AAB468) {
//We got sync!
//printf("Sync on framecount = %u\n", framecount);
sync_missed = 0;
} else if ((bitbuffer & 0x00FFFFFF) == 0xAAAAAA) {
//End of transmission
//printf("End of transmission\n");
goto end;
} else if (framecount % 21 == 0) {
printf("Missed sync on framecount = %u, value = %x/%x/%x\n",
framecount, slowdata[0], slowdata[1], slowdata[2]);
sync_missed++;
} else if (framecount != 0 && (bitbuffer & 0x00FFFFFF) != 0x000000) {
slowdata[0] ^= 0x70;
slowdata[1] ^= 0x4f;
slowdata[2] ^= 0x93;
//printf("unscrambled- %s",slowdata);
} else if (framecount == 0) {
//printf("never scrambled-%s\n",slowdata);
}
framecount++;
}
end:
return total_errs;
}
#define SCRAMBLER_TABLE_BITS_LENGTH 720
static const unsigned char SCRAMBLER_TABLE_BITS[SCRAMBLER_TABLE_BITS_LENGTH+1] = {
0,0,0,0,1,1,1,0,1,1,1,1,0,0,1,0,1,1,0,0,1,0,0,1,0,0,0,0,0,0,1,0,
0,0,1,0,0,1,1,0,0,0,1,0,1,1,1,0,1,0,1,1,0,1,1,0,0,0,0,0,1,1,0,0,
1,1,0,1,0,1,0,0,1,1,1,0,0,1,1,1,1,0,1,1,0,1,0,0,0,0,1,0,1,0,1,0,
1,1,1,1,1,0,1,0,0,1,0,1,0,0,0,1,1,0,1,1,1,0,0,0,1,1,1,1,1,1,1,0,
0,0,0,1,1,1,0,1,1,1,1,0,0,1,0,1,1,0,0,1,0,0,1,0,0,0,0,0,0,1,0,0,
0,1,0,0,1,1,0,0,0,1,0,1,1,1,0,1,0,1,1,0,1,1,0,0,0,0,0,1,1,0,0,1,
1,0,1,0,1,0,0,1,1,1,0,0,1,1,1,1,0,1,1,0,1,0,0,0,0,1,0,1,0,1,0,1,
1,1,1,1,0,1,0,0,1,0,1,0,0,0,1,1,0,1,1,1,0,0,0,1,1,1,1,1,1,1,0,0,
0,0,1,1,1,0,1,1,1,1,0,0,1,0,1,1,0,0,1,0,0,1,0,0,0,0,0,0,1,0,0,0,
1,0,0,1,1,0,0,0,1,0,1,1,1,0,1,0,1,1,0,1,1,0,0,0,0,0,1,1,0,0,1,1,
0,1,0,1,0,0,1,1,1,0,0,1,1,1,1,0,1,1,0,1,0,0,0,0,1,0,1,0,1,0,1,1,
1,1,1,0,1,0,0,1,0,1,0,0,0,1,1,0,1,1,1,0,0,0,1,1,1,1,1,1,1,0,0,0,
0,1,1,1,0,1,1,1,1,0,0,1,0,1,1,0,0,1,0,0,1,0,0,0,0,0,0,1,0,0,0,1,
0,0,1,1,0,0,0,1,0,1,1,1,0,1,0,1,1,0,1,1,0,0,0,0,0,1,1,0,0,1,1,0,
1,0,1,0,0,1,1,1,0,0,1,1,1,1,0,1,1,0,1,0,0,0,0,1,0,1,0,1,0,1,1,1,
1,1,0,1,0,0,1,0,1,0,0,0,1,1,0,1,1,1,0,0,0,1,1,1,1,1,1,1,0,0,0,0,
1,1,1,0,1,1,1,1,0,0,1,0,1,1,0,0,1,0,0,1,0,0,0,0,0,0,1,0,0,0,1,0,
0,1,1,0,0,0,1,0,1,1,1,0,1,0,1,1,0,1,1,0,0,0,0,0,1,1,0,0,1,1,0,1,
0,1,0,0,1,1,1,0,0,1,1,1,1,0,1,1,0,1,0,0,0,0,1,0,1,0,1,0,1,1,1,1,
1,0,1,0,0,1,0,1,0,0,0,1,1,0,1,1,1,0,0,0,1,1,1,1,1,1,1,0,0,0,0,1,
1,1,0,1,1,1,1,0,0,1,0,1,1,0,0,1,0,0,1,0,0,0,0,0,0,1,0,0,0,1,0,0,
1,1,0,0,0,1,0,1,1,1,0,1,0,1,1,0,1,1,0,0,0,0,0,1,1,0,0,1,1,0,1,0,
1,0,0,1,1,1,0,0,1,1,1,1,0,1,1,0
};
unsigned int processDSTAR_HD(dsd_opts * opts, dsd_state * state) {
int radioheaderbuffer[660];
unsigned char radioheaderbuffer2[660];
unsigned int i, j = 0, bitcount = 0;
unsigned char radioheader[41];
for (i = 0; i < 660; i++) {
radioheaderbuffer2[i] = getDibit(opts, state);
radioheaderbuffer2[i] ^= SCRAMBLER_TABLE_BITS[i];
}
for (i = 0; i < 660; i++) {
radioheaderbuffer[j] = radioheaderbuffer2[i];
j += 24;
if (j >= 672) {
j -= 671;
} else if (j >= 660) {
j -= 647;
}
}
// Note: These routines contain GPLed code. Remove if you object to that.
// Due to this, they are in a separate source file.
FECdecoder(radioheaderbuffer, radioheaderbuffer2);
// note we receive 330 bits, but we only use 328 of them (41 octets)
// bits 329 and 330 are unused
for (i = 0; i < 41; i++) {
radioheader[i] = 0;
}
for (i = 0; i < 328; i++) {
if (radioheaderbuffer2[i]) {
radioheader[(bitcount >> 3)] |= (1U << (bitcount & 7));
}
bitcount++;
}
// print header
#ifdef DEBUG_DSTAR_HD
printf("\nDSTAR HEADER: ");
printf("FLAG1: %02X - FLAG2: %02X - FLAG3: %02X\n", radioheader[0],
radioheader[1], radioheader[2]);
printf("RPT 2: %c%c%c%c%c%c%c%c ", radioheader[3], radioheader[4],
radioheader[5], radioheader[6], radioheader[7], radioheader[8],
radioheader[9], radioheader[10]);
printf("RPT 1: %c%c%c%c%c%c%c%c ", radioheader[11], radioheader[12],
radioheader[13], radioheader[14], radioheader[15], radioheader[16],
radioheader[17], radioheader[18]);
printf("YOUR: %c%c%c%c%c%c%c%c ", radioheader[19], radioheader[20],
radioheader[21], radioheader[22], radioheader[23], radioheader[24],
radioheader[25], radioheader[26]);
printf("MY: %c%c%c%c%c%c%c%c/%c%c%c%c\n", radioheader[27],
radioheader[28], radioheader[29], radioheader[30], radioheader[31],
radioheader[32], radioheader[33], radioheader[34], radioheader[35],
radioheader[36], radioheader[37], radioheader[38]);
#endif
//We officially have sync now, so just pass on to the above routine:
return processDSTAR(opts, state);
}