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pico_tnc/pico_tnc/decode.c

340 wiersze
9.4 KiB
C
Czysty Wina Historia

/*
Copyright (c) 2021, Kazuhisa Yokota, JN1DFF
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
* Neither the name of the <organization> nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include "pico/stdlib.h"
//#include "timer.h"
#include "tnc.h"
#include "bell202.h"
#include "ax25.h"
#include "usb_output.h"
#include "tty.h"
#include "digipeat.h"
#include "kiss.h"
#define FCS_OK 0x0f47
//#define FCS_OK (0x0f47 ^ 0xffff)
#define MIN_LEN (7 * 2 + 1 + 1 + 2) // Address field *2, Control, PID, FCS
#define STR_LEN 64
static uint8_t str[STR_LEN];
static void display_packet(tty_t *ttyp, tnc_t *tp)
{
int i;
int in_addr = 1;
int len = tp->data_cnt;
uint8_t *data = tp->data;
int size;
#if PORT_N > 1
size = snprintf(str, STR_LEN, "(%d) %d:%d:", tnc_time(), tp->port, tp->pkt_cnt);
tty_write(ttyp, str, size);
#endif
for (i = 0; i < len - 2; i++) {
int c;
if (i < 7) c = data[i + 7]; // src addr
else if (i < 14) c = data[i - 7]; // dst addr
else c = data[i];
if (in_addr) {
int d = c >> 1;
if (i % 7 == 6) { // SSID
if (i >= 7) in_addr = !(data[i] & 1); // check address extension bit
if (d & 0x0f) { // SSID
size = snprintf(str, STR_LEN, "-%d", d & 0x0f);
tty_write(ttyp, str, size);
}
if (i >= 14 && (c & 0x80)) tty_write_char(ttyp, '*'); // H bit
if (i == 6) tty_write_char(ttyp, '>');
else tty_write_char(ttyp, in_addr ? ',' : ':');
} else { // CALLSIGN
if (d >= '0' && d <= '9') tty_write_char(ttyp, d);
else if (d >= 'A' && d <= 'Z') tty_write_char(ttyp, d);
else if (d != ' ') {
size = snprintf(str, STR_LEN, "<%02x>", d);
tty_write(ttyp, str, size);
}
}
} else {
if (c >= ' ' && c <= '~') tty_write_char(ttyp, c);
else {
size = snprintf(str, STR_LEN, "<%02x>", c);
tty_write(ttyp, str, size);
}
}
}
#if 1
tty_write_str(ttyp, "\r\n");
#else
size = snprintf(str, STR_LEN, "<%02x%02x>\r\n", data[len-1], data[len-2]);
tty_write(ttyp, str, size);
#endif
}
static void output_packet(tnc_t *tp)
{
int len = tp->data_cnt;
uint8_t *data = tp->data;
if (len < MIN_LEN) return;
// FCS check
if (ax25_fcs(0, data, len) != FCS_OK) return;
// count received packet
++tp->pkt_cnt;
// digipeat
if (param.digi) digipeat(tp);
for (int i = TTY_USB; i <= TTY_UART0; i++) {
tty_t *ttyp = &tty[i];
if (ttyp->kiss_mode) kiss_output(ttyp, tp); // kiss mode
else {
// TNC MONitor command
switch (param.mon) {
case MON_ALL:
display_packet(ttyp, tp);
break;
case MON_ME:
if (ax25_callcmp(&param.mycall, &data[0])) { // dst addr check
display_packet(ttyp, tp);
}
}
}
}
}
#define AX25_FLAG 0x7e
static void decode_bit(tnc_t *tp, int bit)
{
tp->flag <<= 1;
tp->flag |= bit;
switch (tp->state) {
case FLAG:
if (tp->flag == AX25_FLAG) { // found flag
tp->state = DATA;
tp->data_cnt = 0;
tp->data_bit_cnt = 0;
//fprintf(stderr, "found AX25_FALG\n");
}
break;
case DATA:
if ((tp->flag & 0x3f) == 0x3f) { // AX.25 flag, end of packet, six continuous "1" bits
output_packet(tp);
tp->state = FLAG;
break;
}
if ((tp->flag & 0x3f) == 0x3e) break; // delete bit stuffing bit
tp->data_byte >>= 1;
tp->data_byte |= bit << 7;
tp->data_bit_cnt++;
if (tp->data_bit_cnt >= 8) {
if (tp->data_cnt < DATA_LEN) tp->data[tp->data_cnt++] = tp->data_byte;
else {
printf("packet too long > %d\n", tp->data_cnt);
tp->state = FLAG;
break;
}
tp->data_bit_cnt = 0;
}
}
}
static void decode(tnc_t *tp, int val)
{
tp->edge++;
if (val != tp->pval) {
// int bits = (edge + SAMPLING_N/2) / SAMPLING_N;
int bits = (tp->edge * BAUD_RATE*2 + SAMPLING_RATE) / (SAMPLING_RATE * 2);
//printf("%d,", bits);
decode_bit(tp, 0); // NRZI
while (--bits > 0) {
decode_bit(tp, 1);
}
tp->edge = 0;
tp->pval = val;
}
}
#define PLL_STEP ((int)(((1ULL << 32) + SAMPLING_N/2) / SAMPLING_N))
// DireWolf PLL
static void decode2(tnc_t *tp, int val)
{
int32_t prev_pll = tp->pll_counter >> 31; // compiler bug workaround
tp->pll_counter += PLL_STEP;
if ((tp->pll_counter >> 31) < prev_pll) { // overflow
decode_bit(tp, val == tp->nrzi); // decode NRZI
tp->nrzi = val;
}
if (val != tp->pval) {
// adjust PLL counter
tp->pll_counter -= tp->pll_counter >> 2; // 0.75
tp->pval = val;
}
}
void demodulator(tnc_t *tp, int adc)
{
int val;
int bit;
//printf("%d,", adc);
//dac_output_voltage(DAC_CHANNEL_1, adc >> 4);
#define AVERAGE_MUL 256
#define AVERAGE_N 64
#define AVERAGE_SHIFT 6
#define CDT_AVG_N 128
#define CDT_MUL 256
#define CDT_SHIFT 6
// update average value
tp->avg += (adc * AVERAGE_MUL - tp->avg) >> AVERAGE_SHIFT;
val = adc - (tp->avg + AVERAGE_MUL/2) / AVERAGE_MUL;
// carrier detect
tp->cdt_lvl += (val * val * CDT_MUL - tp->cdt_lvl) >> CDT_SHIFT;
#if 0
static int count = 0;
if ((++count & ((1 << 16) - 1)) == 0) {
printf("(%u) decode: adc: %d, cdt_lvl: %d, avg: %d, port = %d\n", tnc_time(), adc, tp->cdt_lvl, tp->avg, tp->port);
}
#endif
#define CDT_THR_LOW 1024
#define CDT_THR_HIGH (CDT_THR_LOW * 2) // low +6dB
if (!tp->cdt && tp->cdt_lvl > CDT_THR_HIGH) { // CDT on
gpio_put(tp->cdt_pin, 1);
tp->cdt = true;
//printf("(%u) decode: CDT on, adc: %d, cdt_lvl: %d, avg: %d, port = %d\n", tnc_time(), adc, tp->cdt_lvl, tp->avg, tp->port);
//printf("(%u) decode: cdt on, port = %d\n", tnc_time(), tp->port);
} else if (tp->cdt && tp->cdt_lvl < CDT_THR_LOW) { // CDT off
gpio_put(tp->cdt_pin, 0);
tp->cdt = false;
//printf("(%u) decode: CDT off, adc: %d, cdt_lvl: %d, avg: %d, port = %d\n", tnc_time(), adc, tp->cdt_lvl, tp->avg, tp->port);
//printf("(%u) decode: cdt off, port = %d\n", tnc_time(), tp->port);
}
if (!tp->cdt) return;
#if 0
sum += adc;
if (++count >= AVERAGE_N) {
average = sum / AVERAGE_N;
//ESP_LOGI(TAG, "average adc value = %d", average);
sum = 0;
count = 0;
}
#else
//tp->average = (tp->average * (AVERAGE_N - 1) + adc + AVERAGE_N/2) / AVERAGE_N;
/*
if (count >= 13200) {
printf("average = %d\n", average);
count = 0;
}
*/
#endif
#define LPF_N SAMPLING_N
//val = bell202_decode((int)adc - average);
//val = bell202_decode((int)adc - 2048);
//val = bell202_decode(tp, adc); // delayed decode
#ifdef BELL202_SYNC
val = bell202_decode2(tp, adc); // sync decode
#else
val = bell202_decode(tp, adc); // delayed decode
#endif
//lpf = (lpf * (LPF_N-1) + val) / LPF_N;
//printf("demodulator(%d) = %d\n", adc, val);
#if 0
static uint32_t count = 0;
if (count < 132) {
printf("%d, %d\n", adc, val);
}
if (++count >= 13200 * 10) {
count = 0;
printf("----------------\n");
}
#endif
#define LPF_THRESHOLD (1 << 12)
//printf("bit val = %d\n", val);
if (val < -LPF_THRESHOLD) tp->bit = 1;
else if (val >= LPF_THRESHOLD) tp->bit = 0;
//dac_output_voltage(DAC_CHANNEL_2, bit * 128);
//printf("%d\n", bit);
#ifdef DECODE_PLL
decode2(tp, tp->bit); // Direwolf PLL
#else
decode(tp, tp->bit); // bit length
#endif
}
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