--- /dev/null
+/**
+ * \file
+ * <!--
+ * This file is part of BeRTOS.
+ *
+ * Bertos is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * As a special exception, you may use this file as part of a free software
+ * library without restriction. Specifically, if other files instantiate
+ * templates or use macros or inline functions from this file, or you compile
+ * this file and link it with other files to produce an executable, this
+ * file does not by itself cause the resulting executable to be covered by
+ * the GNU General Public License. This exception does not however
+ * invalidate any other reasons why the executable file might be covered by
+ * the GNU General Public License.
+ *
+ * Copyright 2009 Develer S.r.l. (http://www.develer.com/)
+ *
+ * -->
+ * \brief Simple AX25 data link layer implementation.
+ *
+ * For now, only UI frames without any Layer 3 protocol are handled.
+ * This however is enough to send/receive APRS packets.
+ *
+ * \version $Id$
+ * \author Francesco Sacchi <batt@develer.com>
+ *
+ */
+
+#include "ax25.h"
+#include "cfg/cfg_ax25.h"
+
+#include <drv/afsk.h>
+#include <algo/crc_ccitt.h>
+
+#define LOG_LEVEL AX25_LOG_LEVEL
+#define LOG_FORMAT AX25_LOG_FORMAT
+#include <cfg/log.h>
+
+#include <string.h> //memset
+
+#define DECODE_CALL(buf, addr) \
+ for (unsigned i = 0; i < sizeof((addr)); i++) \
+ { \
+ ASSERT(!(*(buf) & 0x01)); \
+ (addr)[i] = *(buf)++ >> 1; \
+ }
+
+static void ax25_decode(AX25Ctx *ctx)
+{
+ AX25Msg msg;
+ uint8_t *buf = ctx->buf;
+
+ DECODE_CALL(buf, msg.dst.call);
+ ASSERT(!(*buf & 0x01));
+ msg.dst.ssid = (*buf++ >> 1) & 0x0F;
+
+ DECODE_CALL(buf, msg.src.call);
+ msg.src.ssid = (*buf >> 1) & 0x0F;
+
+ LOG_INFO("SRC[%.6s-%d], DST[%.6s-%d]\n", msg.src.call, msg.src.ssid, msg.dst.call, msg.dst.ssid);
+
+ /* Repeater addresses */
+ #if CONFIG_AX25_RPT_LST
+ for (msg.rpt_cnt = 0; !(*buf++ & 0x01) && (msg.rpt_cnt < countof(msg.rpt_lst)); msg.rpt_cnt++)
+ {
+ DECODE_CALL(buf, msg.rpt_lst[msg.rpt_cnt].call);
+ msg.rpt_lst[msg.rpt_cnt].ssid = (*buf >> 1) & 0x0F;
+ LOG_INFO("RPT%d[%.6s-%d]\n", msg.rpt_cnt, msg.rpt_lst[msg.rpt_cnt].call, msg.rpt_lst[msg.rpt_cnt].ssid);
+ }
+ #else
+ while (!(*buf++ & 0x01))
+ {
+ char rpt[6];
+ uint8_t ssid;
+ DECODE_CALL(buf, rpt);
+ ssid = (*buf >> 1) & 0x0F;
+ LOG_INFO("RPT[%.6s-%d]\n", rpt, ssid);
+ }
+ #endif
+
+ msg.ctrl = *buf++;
+ if (msg.ctrl != AX25_CTRL_UI)
+ {
+ LOG_INFO("Only UI frames are handled, got [%02X]\n", msg.ctrl);
+ return;
+ }
+
+ msg.pid = *buf++;
+ if (msg.pid != AX25_PID_NOLAYER3)
+ {
+ LOG_INFO("Only frames without layer3 protocol are handled, got [%02X]\n", msg.pid);
+ return;
+ }
+
+ msg.len = ctx->frm_len - 2 - (buf - ctx->buf);
+ msg.info = buf;
+ LOG_INFO("DATA[%.*s]\n", msg.len, msg.info);
+
+ if (ctx->hook)
+ ctx->hook(&msg);
+}
+
+void ax25_poll(AX25Ctx *ctx)
+{
+ int c;
+
+ while ((c = kfile_getc(ctx->ch)) != EOF)
+ {
+ if (!ctx->escape && c == HDLC_FLAG)
+ {
+ LOG_INFO("Frame start\n");
+ if (ctx->frm_len >= AX25_MIN_FRAME_LEN)
+ {
+ if (ctx->crc_in == AX25_CRC_CORRECT)
+ {
+ LOG_INFO("Frame found!\n");
+ ax25_decode(ctx);
+ }
+ else
+ {
+ LOG_INFO("CRC error, computed [%04X]\n", ctx->crc_in);
+ }
+ }
+ ctx->sync = true;
+ ctx->crc_in = CRC_CCITT_INIT_VAL;
+ ctx->frm_len = 0;
+ continue;
+ }
+
+ if (!ctx->escape && c == HDLC_RESET)
+ {
+ LOG_INFO("HDLC reset\n");
+ ctx->sync = false;
+ continue;
+ }
+
+ if (!ctx->escape && c == AX25_ESC)
+ {
+ ctx->escape = true;
+ continue;
+ }
+
+ if (ctx->sync)
+ {
+ if (ctx->frm_len < CONFIG_AX25_FRAME_BUF_LEN)
+ {
+ ctx->buf[ctx->frm_len++] = c;
+ ctx->crc_in = updcrc_ccitt(c, ctx->crc_in);
+ }
+ else
+ {
+ LOG_INFO("Buffer overrun");
+ ctx->sync = false;
+ }
+ }
+ ctx->escape = false;
+ }
+
+ if (kfile_error(ctx->ch))
+ {
+ LOG_ERR("Channel error [%04x]\n", kfile_error(ctx->ch));
+ kfile_clearerr(ctx->ch);
+ }
+}
+
+void ax25_init(AX25Ctx *ctx, KFile *channel, ax25_callback_t hook)
+{
+ ASSERT(ctx);
+ ASSERT(channel);
+
+ memset(ctx, 0, sizeof(*ctx));
+ ctx->ch = channel;
+ ctx->hook = hook;
+ ctx->crc_in = ctx->crc_out = CRC_CCITT_INIT_VAL;
+}
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