OpenModem/protocol/AX25.c

92 lines
2.7 KiB
C
Executable File

// Based on work by Francesco Sacchi
#include <string.h>
#include <ctype.h>
#include "AX25.h"
#include "protocol/HDLC.h"
#include "util/CRC-CCIT.h"
#include "../hardware/AFSK.h"
#define countof(a) sizeof(a)/sizeof(a[0])
#define MIN(a,b) ({ typeof(a) _a = (a); typeof(b) _b = (b); ((typeof(_a))((_a < _b) ? _a : _b)); })
#define DECODE_CALL(buf, addr) for (unsigned i = 0; i < sizeof((addr)); i++) { char c = (*(buf)++ >> 1); (addr)[i] = (c == ' ') ? '\x0' : c; }
#define AX25_SET_REPEATED(msg, idx, val) do { if (val) { (msg)->rpt_flags |= _BV(idx); } else { (msg)->rpt_flags &= ~_BV(idx) ; } } while(0)
void ax25_init(AX25Ctx *ctx, Afsk *modem, FILE *channel, ax25_callback_t hook) {
memset(ctx, 0, sizeof(*ctx));
ctx->ch = channel;
ctx->modem = modem;
ctx->hook = hook;
ctx->crc_in = ctx->crc_out = CRC_CCIT_INIT_VAL;
ctx->ready_for_data = true;
}
static void ax25_decode(AX25Ctx *ctx) {
if (ctx->hook) ctx->hook(ctx);
}
void ax25_poll(AX25Ctx *ctx) {
int c;
while ((c = fgetc(ctx->ch)) != EOF) {
if (!ctx->escape && c == HDLC_FLAG) {
if (ctx->frame_len >= AX25_MIN_FRAME_LEN) {
if (ctx->crc_in == AX25_CRC_CORRECT || CONFIG_PASSALL) {
#if OPEN_SQUELCH == true
LED_RX_ON();
#endif
ax25_decode(ctx);
}
}
ctx->sync = true;
ctx->crc_in = CRC_CCIT_INIT_VAL;
ctx->frame_len = 0;
continue;
}
if (!ctx->escape && c == HDLC_RESET) {
ctx->sync = false;
continue;
}
if (!ctx->escape && c == AX25_ESC) {
ctx->escape = true;
continue;
}
if (ctx->sync) {
if (ctx->frame_len < AX25_MAX_FRAME_LEN) {
ctx->buf[ctx->frame_len++] = c;
ctx->crc_in = update_crc_ccit(c, ctx->crc_in);
} else {
ctx->sync = false;
}
}
ctx->escape = false;
}
}
static void ax25_putchar(AX25Ctx *ctx, uint8_t c)
{
if (c == HDLC_FLAG || c == HDLC_RESET || c == AX25_ESC) fputc(AX25_ESC, ctx->ch);
ctx->crc_out = update_crc_ccit(c, ctx->crc_out);
fputc(c, ctx->ch);
}
void ax25_sendRaw(AX25Ctx *ctx, void *_buf, size_t len) {
ctx->ready_for_data = false;
ctx->crc_out = CRC_CCIT_INIT_VAL;
fputc(HDLC_FLAG, ctx->ch);
const uint8_t *buf = (const uint8_t *)_buf;
while (len--) ax25_putchar(ctx, *buf++);
uint8_t crcl = (ctx->crc_out & 0xff) ^ 0xff;
uint8_t crch = (ctx->crc_out >> 8) ^ 0xff;
ax25_putchar(ctx, crcl);
ax25_putchar(ctx, crch);
fputc(HDLC_FLAG, ctx->ch);
ctx->ready_for_data = true;
}