Initial testing code.

Makefile

@@ -15,7 +15,7 @@ all:
 
 xgen_gdl90:
 	go get -t -d -v ./main ./godump978 ./uatparse ./sensors
-	go build $(BUILDINFO) -p 4 main/gen_gdl90.go main/traffic.go main/gps.go main/network.go main/managementinterface.go main/sdr.go main/ping.go main/uibroadcast.go main/monotonic.go main/datalog.go main/equations.go main/sensors.go main/cputemp.go
+	go build $(BUILDINFO) -p 4 main/gen_gdl90.go main/traffic.go main/gps.go main/network.go main/managementinterface.go main/sdr.go main/ping.go main/uibroadcast.go main/monotonic.go main/datalog.go main/equations.go main/sensors.go main/cputemp.go main/lowpower_uat.go
 
 fancontrol:
 	go get -t -d -v ./main

main/gen_gdl90.go

@@ -1486,6 +1486,7 @@ func main() {
 	crcInit() // Initialize CRC16 table.
 
 	sdrInit()
+	initUATRadioSerial()
 	pingInit()
 	initTraffic()
 

main/lowpower_uat.go

@@ -0,0 +1,128 @@
+package main
+
+import (
+	"encoding/hex"
+	"errors"
+	"github.com/uavionix/serial"
+	"log"
+	"unsafe"
+)
+
+/*
+
+#cgo LDFLAGS: -ldump978
+
+#include <stdint.h>
+#include "../dump978/fec.h"
+
+*/
+import "C"
+
+var radioSerialConfig *serial.Config
+var radioSerialPort *serial.Port
+
+func initUATRadioSerial() error {
+	// Init for FEC routines.
+	C.init_fec()
+	// Initialize port at 2Mbaud.
+	radioSerialConfig = &serial.Config{Name: "/dev/ttyACM0", Baud: 2000000}
+	p, err := serial.OpenPort(radioSerialConfig)
+	if err != nil {
+		log.Printf("serial port err: %s\n", err.Error())
+		return errors.New("serial port failed to initialize")
+	}
+
+	radioSerialPort = p
+
+	// Start a goroutine to watch the serial port.
+	go radioSerialPortReader()
+	return nil
+}
+
+/*
+	radioSerialPortReader().
+	 Loop to read data from the radio serial port.
+*/
+var radioMagic = []byte{0x0a, 0xb0, 0xcd, 0xe0}
+
+func radioSerialPortReader() {
+	tmpBuf := make([]byte, 1024) // Read buffer.
+	var buf []byte               // Message buffer.
+	if radioSerialPort == nil {
+		return
+	}
+	defer radioSerialPort.Close()
+	for {
+		n, err := radioSerialPort.Read(tmpBuf)
+		if err != nil {
+			log.Printf("serial port err, shutting down radio: %s\n", err.Error())
+			return
+		}
+		buf = append(buf, tmpBuf[:n]...)
+		bufLen := len(buf)
+		var finBuf []byte   // Truncated buffer, with processed messages extracted.
+		var numMessages int // Number of messages extracted.
+		// Search for a suitable message to extract.
+		for i := 0; i < bufLen-6; i++ {
+			if (buf[i] == radioMagic[0]) && (buf[i+1] == radioMagic[1]) && (buf[i+2] == radioMagic[2]) && (buf[i+3] == radioMagic[3]) {
+				// Found the magic sequence. Get the length.
+				msgLen := int(uint16(buf[i+4]) + (uint16(buf[i+5]) << 8))
+				// Check if we've read enough to finish this message.
+				if bufLen < i+6+msgLen {
+					break // Wait for more of the message to come in.
+				}
+				// Message is long enough.
+				processRadioMessage(buf[i+6 : i+6+msgLen])
+				// Remove everything in the buffer before this message.
+				finBuf = buf[i+6+msgLen:]
+				numMessages++
+			}
+		}
+		if numMessages > 0 {
+			buf = finBuf
+		}
+	}
+}
+
+/*
+	processRadioMessage().
+	 Processes a single message from the radio. De-interleaves (when necessary), checks Reed-Solomon, passes to main process.
+*/
+
+func processRadioMessage(msg []byte) {
+	log.Printf("processRadioMessage(): %d %s\n", len(msg), hex.EncodeToString(msg))
+	var toRelay string
+	switch len(msg) {
+	case 552:
+		to := make([]byte, 552)
+		var rs_errors int
+		i := int(C.correct_uplink_frame((*C.uint8_t)(unsafe.Pointer(&msg[0])), (*C.uint8_t)(unsafe.Pointer(&to[0])), (*C.int)(unsafe.Pointer(&rs_errors))))
+		toRelay = "+" + hex.EncodeToString(to[:432]) + ";"
+		log.Printf("i=%d, rs_errors=%d, msg=%s\n", i, rs_errors, toRelay)
+	case 48:
+		to := make([]byte, 48)
+		copy(to, msg)
+		var rs_errors int
+		i := int(C.correct_adsb_frame((*C.uint8_t)(unsafe.Pointer(&to[0])), (*C.int)(unsafe.Pointer(&rs_errors))))
+		if i == 1 {
+			// Short ADS-B frame.
+			toRelay = "-" + hex.EncodeToString(to[:18]) + ";"
+			log.Printf("i=%d, rs_errors=%d, msg=%s\n", i, rs_errors, toRelay)
+		} else if i == 2 {
+			// Long ADS-B frame.
+			toRelay = "-" + hex.EncodeToString(to[:34]) + ";"
+			log.Printf("i=%d, rs_errors=%d, msg=%s\n", i, rs_errors, toRelay)
+		} else {
+			log.Printf("i=%d, rs_errors=%d, msg=%s\n", i, rs_errors, hex.EncodeToString(to))
+		}
+	default:
+		log.Printf("processRadioMessage(): unhandled message size %d\n", len(msg))
+	}
+
+	if len(toRelay) > 0 {
+		o, msgtype := parseInput(toRelay)
+		if o != nil && msgtype != 0 {
+			relayMessage(msgtype, o)
+		}
+	}
+}