Implement airspy_adsb send support.

airspy_adsb.c

@@ -6,6 +6,8 @@
 #include "receive.h"
 #include "airspy_adsb.h"
 
+#define SEND_MHZ 20
+
 struct __attribute__((packed)) airspy_adsb_common_overlay {
 	char mlat_timestamp[8];
 	char semicolon1;
@@ -85,6 +87,42 @@ static bool airspy_adsb_parse_mode_s_long(struct buf *buf, struct packet *packet
 	return true;
 }
 
+static void airspy_adsb_fill_common(struct packet *packet, struct airspy_adsb_common_overlay *overlay) {
+	overlay->semicolon1 = overlay->semicolon2 = overlay->semicolon3 = ';';
+	hex_from_int(
+			overlay->mlat_timestamp,
+			mlat_timestamp_scale_out(packet->mlat_timestamp, UINT32_MAX, SEND_MHZ),
+			sizeof(overlay->mlat_timestamp) / 2);
+	hex_from_int(overlay->mlat_precision, SEND_MHZ / 2, sizeof(overlay->mlat_precision) / 2);
+	hex_from_int(overlay->rssi, rssi_scale_out(packet->rssi, UINT16_MAX), sizeof(overlay->rssi) / 2);
+}
+
+static void airspy_adsb_serialize_mode_s_short(struct packet *packet, struct buf *buf) {
+	struct airspy_adsb_mode_s_short_overlay *overlay = (struct airspy_adsb_mode_s_short_overlay *) buf_at(buf, 0);
+	overlay->asterisk = '*';
+	overlay->semicolon = ';';
+	overlay->cr = '\r';
+	overlay->lf = '\n';
+	hex_from_bin(overlay->payload, packet->payload, sizeof(overlay->payload) / 2);
+
+	airspy_adsb_fill_common(packet, &overlay->common);
+
+	buf->length = sizeof(*overlay);
+}
+
+static void airspy_adsb_serialize_mode_s_long(struct packet *packet, struct buf *buf) {
+	struct airspy_adsb_mode_s_long_overlay *overlay = (struct airspy_adsb_mode_s_long_overlay *) buf_at(buf, 0);
+	overlay->asterisk = '*';
+	overlay->semicolon = ';';
+	overlay->cr = '\r';
+	overlay->lf = '\n';
+	hex_from_bin(overlay->payload, packet->payload, sizeof(overlay->payload) / 2);
+
+	airspy_adsb_fill_common(packet, &overlay->common);
+
+	buf->length = sizeof(*overlay);
+}
+
 void airspy_adsb_init() {
 	assert(sizeof(struct airspy_adsb_parser_state) <= PARSER_STATE_LEN);
 	assert(sizeof(struct airspy_adsb_mode_s_short_overlay) < BUF_LEN_MAX);
@@ -98,3 +136,19 @@ bool airspy_adsb_parse(struct buf *buf, struct packet *packet, void *state_in) {
 			airspy_adsb_parse_mode_s_short(buf, packet, state) ||
 			airspy_adsb_parse_mode_s_long(buf, packet, state));
 }
+
+void airspy_adsb_serialize(struct packet *packet, struct buf *buf) {
+	if (!packet) {
+		return;
+	}
+
+	switch (packet->type) {
+		case MODE_S_SHORT:
+			airspy_adsb_serialize_mode_s_short(packet, buf);
+			break;
+
+		case MODE_S_LONG:
+			airspy_adsb_serialize_mode_s_long(packet, buf);
+			break;
+	}
+}

airspy_adsb.h

@@ -7,3 +7,4 @@ struct packet;
 
 void airspy_adsb_init();
 bool airspy_adsb_parse(struct buf *, struct packet *, void *);
+void airspy_adsb_serialize(struct packet *, struct buf *);

common.c

@@ -163,6 +163,14 @@ void hex_from_bin(char *out, const uint8_t *in, size_t bytes) {
 	}
 }
 
+void hex_from_int(char *out, uint64_t in, size_t bytes) {
+	bytes *= 2;
+	for (int o = bytes - 1; o >= 0; o--) {
+		out[o] = hex_char_table[in & 0xf];
+		in >>= 4;
+	}
+}
+
 
 void uuid_gen(char *out) {
 	uuid_t uuid;

common.h

@@ -85,6 +85,7 @@ void hex_init();
 void hex_to_bin(uint8_t *, const char *, size_t);
 uint64_t hex_to_int(const char *, size_t);
 void hex_from_bin(char *, const uint8_t *, size_t);
+void hex_from_int(char *, uint64_t, size_t);
 
 
 ///////// uuid

send.c

@@ -11,6 +11,7 @@
 
 #include "send.h"
 
+#include "airspy_adsb.h"
 #include "beast.h"
 #include "json.h"
 #include "raw.h"
@@ -30,6 +31,10 @@ struct serializer {
 	serializer serialize;
 	struct send *send_head;
 } serializers[] = {
+	{
+		.name = "airspy_adsb",
+		.serialize = airspy_adsb_serialize,
+	},
 	{
 		.name = "beast",
 		.serialize = beast_serialize,