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29 * Copyright 2009 Develer S.r.l. (http://www.develer.com/)
32 * \brief Simple AX25 data link layer implementation.
34 * For now, only UI frames without any Layer 3 protocol are handled.
35 * This however is enough to send/receive APRS packets.
37 * \author Francesco Sacchi <batt@develer.com>
39 * $WIZ$ module_name = "ax25"
40 * $WIZ$ module_configuration = "bertos/cfg/cfg_ax25.h"
41 * $WIZ$ module_depends = "kfile", "crc-ccitt"
48 #include "cfg/cfg_ax25.h"
50 #include <cfg/compiler.h>
54 * Maximum size of a AX25 frame.
56 #define AX25_MIN_FRAME_LEN 18
59 * CRC computation on correct AX25 packets should
60 * give this result (don't ask why).
62 #define AX25_CRC_CORRECT 0xF0B8
64 struct AX25Msg; // fwd declaration
67 * Type for AX25 messages callback.
69 typedef void (*ax25_callback_t)(struct AX25Msg *msg);
73 * AX25 Protocol context.
75 typedef struct AX25Ctx
77 uint8_t buf[CONFIG_AX25_FRAME_BUF_LEN]; ///< buffer for received chars
78 KFile *ch; ///< KFile used to access the physical medium
79 size_t frm_len; ///< received frame length.
80 uint16_t crc_in; ///< CRC for current received frame
81 uint16_t crc_out; ///< CRC of current sent frame
82 ax25_callback_t hook; ///< Hook function to be called when a message is received
83 bool sync; ///< True if we have received a HDLC flag.
84 bool escape; ///< True when we have to escape the following char.
91 typedef struct AX25Call
93 char call[6]; ///< Call string, max 6 character
94 uint8_t ssid; ///< SSID (secondary station ID) for the call
98 * Create an AX25Call structure on the fly.
99 * \param str callsign, can be 6 characters or shorter.
100 * \param id ssid associated with the callsign.
102 #define AX25_CALL(str, id) {.call = (str), .ssid = (id) }
105 * Maximum number of Repeaters in a AX25 message.
107 #define AX25_MAX_RPT 8
110 * Has to be lesser than 8 in order to fit in one byte
111 * change AX25Msg.rpt_flags if you need more repeaters.
113 STATIC_ASSERT(AX25_MAX_RPT <= 8);
117 * Used to handle AX25 sent/received messages.
119 typedef struct AX25Msg
121 AX25Call src; ///< Source adress
122 AX25Call dst; ///< Destination address
123 #if CONFIG_AX25_RPT_LST
124 AX25Call rpt_lst[AX25_MAX_RPT]; ///< List of repeaters
125 uint8_t rpt_cnt; ///< Number of repeaters in this message
126 uint8_t rpt_flags; ///< Has-been-repeated flags for each repeater (bit-mapped)
127 #define AX25_REPEATED(msg, idx) ((msg)->rpt_flags & BV(idx))
129 uint16_t ctrl; ///< AX25 control field
130 uint8_t pid; ///< AX25 PID field
131 const uint8_t *info; ///< Pointer to the info field (payload) of the message
132 size_t len; ///< Payload length
136 #define AX25_CTRL_UI 0x03
137 #define AX25_PID_NOLAYER3 0xF0
141 * These should be moved in
142 * a separated HDLC related file one day...
145 #define HDLC_FLAG 0x7E
146 #define HDLC_RESET 0x7F
147 #define AX25_ESC 0x1B
152 * Declare an AX25 path.
153 * \param dst the destination callsign for the path, \see AX25_CALL
154 * for a handy way to create a callsign on the fly.
155 * \param src the source callsign for the path, \see AX25_CALL
156 * for a handy way to create a callsign on the fly.
158 * Additional optional callsigns can be specified at the end of this macro
159 * in order to add repeater callsigns or specific unproto paths.
161 * This macro can be used to simply path array declaration.
162 * Should be used in this way:
164 * AX25Call path[] = AX25_PATH(AX25_CALL("abcdef", 0), AX25_CALL("ghjklm", 0), AX25_CALL("wide1", 1), AX25_CALL("wide2", 2));
167 * The declared path can then be passed to ax25_sendVia().
169 #define AX25_PATH(dst, src, ...) { dst, src, ## __VA_ARGS__ }
171 void ax25_poll(AX25Ctx *ctx);
172 void ax25_sendVia(AX25Ctx *ctx, const AX25Call *path, size_t path_len, const void *_buf, size_t len);
175 * Send an AX25 frame on the channel.
176 * \param ctx AX25 context to operate on.
177 * \param dst the destination callsign for the frame, \see AX25_CALL
178 * for a handy way to create a callsign on the fly.
179 * \param src the source callsign for the frame, \see AX25_CALL
180 * for a handy way to create a callsign on the fly.
181 * \param buf payload buffer.
182 * \param len length of the payload.
184 * \see ax25_sendVia() if you want to send a frame with a specific path.
186 #define ax25_send(ctx, dst, src, buf, len) ax25_sendVia(ctx, ({static AX25Call __path[]={dst, src}; __path;}), 2, buf, len)
187 void ax25_init(AX25Ctx *ctx, KFile *channel, ax25_callback_t hook);
189 void ax25_print(KFile *ch, const AX25Msg *msg);
191 int ax25_testSetup(void);
192 int ax25_testTearDown(void);
193 int ax25_testRun(void);
195 #endif /* NET_AX25_H */