void build_packet(const char** parameters)
{
char* data = buffers[OPERATIONAL_BUFFER].data;
// Fill D-PRS header
memcpy(data, "$$CRCxxxx,", DPRS_SIGN_LENGTH);
data += DPRS_SIGN_LENGTH;
// Fill TNC-2 header
data += build_aprs_call(data);
memcpy(data, ">APD4XX,DSTAR*:", 15);
data[5] = (software_version[1] % 10) + '0';
data[6] = (software_version[2] % 24) + 'A';
data += 15;
// Fill APRS payload
data += build_position_report(data, parameters);
// Fill D-PRS/APRS-IS terminator and Slow Data filler
memcpy(data, "\r\n", 2);
data += 2;
memset(data, 0x66, 5);
// Update buffer attributes
int length = data - buffers[OPERATIONAL_BUFFER].data;
buffers[OPERATIONAL_BUFFER].length = length;
buffers[OPERATIONAL_BUFFER].version ++;
// Update CRC in D-PRS header
data = buffers[OPERATIONAL_BUFFER].data;
length -= TNC2_POSITION + 1; // Length from TNC-2 header to CR
uint16_t sum = rx_dstar_crc_data(data + TNC2_POSITION, length);
vdisp_i2s(data + CRC_POSITION, 4, 16, 1, sum);
data[DPRS_SIGN_LENGTH - 1] = ',';
}
static uint32_t get_crc(void)
{
return rx_dstar_crc_data( (uint8_t *) &settings, 504) | (SETTINGS_VERSION << 16);
}
void slowdata_analyze_stream(void)
{
while (slowDataFIFOoutPtr != slowDataFIFOinPtr)
{
char d = (char) slowDataFIFO[slowDataFIFOoutPtr];
slowDataFIFOoutPtr++;
if (slowDataFIFOoutPtr >= SLOWDATA_FIFO_BYTES)
{
slowDataFIFOoutPtr = 0;
}
switch (slowDataGPSA_state)
{
case 0:
if (d == '$')
{
slowDataGPSA_state = 1;
}
break;
case 1:
if (d == '$')
{
slowDataGPSA_state = 2;
}
else
{
slowDataGPSA_state = 0;
}
break;
case 2:
if (d == 'C')
{
slowDataGPSA_state = 3;
}
else
{
slowDataGPSA_state = 0;
}
break;
case 3:
if (d == 'R')
{
slowDataGPSA_state = 4;
}
else
{
slowDataGPSA_state = 0;
}
break;
case 4:
if (d == 'C')
{
slowDataGPSA_state = 5;
}
else
{
slowDataGPSA_state = 0;
}
break;
case 5:
if (d > ' ')
{
slowDataGPSA_state = 6;
crc[0] = d;
}
else
{
slowDataGPSA_state = 0;
}
break;
case 6:
if (d > ' ')
{
slowDataGPSA_state = 7;
crc[1] = d;
}
else
{
slowDataGPSA_state = 0;
}
break;
case 7:
if (d > ' ')
{
slowDataGPSA_state = 8;
crc[2] = d;
}
else
{
slowDataGPSA_state = 0;
}
break;
case 8:
if (d > ' ')
{
slowDataGPSA_state = 9;
crc[3] = d;
}
else
{
slowDataGPSA_state = 0;
}
break;
case 9:
if (d == ',')
{
slowDataGPSA_state = 10;
slowDataGPSA_ptr = 0;
}
else
{
slowDataGPSA_state = 0;
}
break;
case 10:
if (d >= ' ') // printable character
{
if (slowDataGPSA_ptr >= SLOWDATA_GPSA_BUFLEN) // buffer full, line too long
{
slowDataGPSA_state = 0;
}
else
{
slowDataGPSA[slowDataGPSA_ptr] = d;
slowDataGPSA_ptr ++;
}
}
else // everything else including CR
{
slowDataGPSA_state = 0;
if (slowDataGPSA_ptr < SLOWDATA_GPSA_BUFLEN) // buffer not full
{
slowDataGPSA[slowDataGPSA_ptr] = d; // put last character at the end
slowDataGPSA_ptr ++;
// crc[4] = 0;
// vd_prints_xy(VDISP_NODEINFO_LAYER, 80, 16, VDISP_FONT_6x8, 0, crc);
unsigned short sum = rx_dstar_crc_data((unsigned char *) slowDataGPSA, slowDataGPSA_ptr);
char buf[5];
vdisp_i2s(buf, 4, 16, 1, sum);
// buf[4] = 0;
// vd_prints_xy(VDISP_NODEINFO_LAYER, 80, 24, VDISP_FONT_6x8, 0, buf);
if (memcmp(crc, buf, 4) == 0)
{
aprs_send_user_report((unsigned char *) slowDataGPSA, slowDataGPSA_ptr -1); // send GPS-A data without trailing CR
}
}
}
break;
} // switch
} // while
}
