From 462de2843f11f3d3b223e0dc633c897f7cdce8ba Mon Sep 17 00:00:00 2001
From: cyoung <cyoung@gmail.com>
Date: Mon, 11 Jun 2018 16:50:33 -0400
Subject: [PATCH] Revert back to FEC calculating code.

---
 main/lowpower_uat.go | 66 ++++++++++++++++++++++++++------------------
 1 file changed, 39 insertions(+), 27 deletions(-)

diff --git a/main/lowpower_uat.go b/main/lowpower_uat.go
index af15c7ad..bcd8f42c 100644
--- a/main/lowpower_uat.go
+++ b/main/lowpower_uat.go
@@ -3,16 +3,27 @@ package main
 import (
 	"encoding/hex"
 	"errors"
-	"fmt"
 	"github.com/uavionix/serial"
 	"log"
-	"math"
+	"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)
@@ -55,7 +66,7 @@ func radioSerialPortReader() {
 		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)) + 6 // 6 bytes for rs_errors, RSSI, and TS.
+				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.
@@ -80,33 +91,34 @@ func radioSerialPortReader() {
 
 func processRadioMessage(msg []byte) {
 	log.Printf("processRadioMessage(): %d %s\n", len(msg), hex.EncodeToString(msg))
-
-	// rs_errors, RSSI, and message timestamp are prepended to the actual packet.
-
-	// rs_errors.
-	rs_errors := int8(msg[0])
-
-	// RSSI
-	rssiRaw := int8(msg[1])
-	rssiAdjusted := int16(rssiRaw) - 132 // -132 dBm, calculated minimum RSSI.
-	l := math.Pow(10.0, float64(rssiAdjusted)/20.0)
-	rssiDump978 := int16(1000.0 * l)
-
-	// Timestamp.
-	//ts := uint32(msg[2]) + (uint32(msg[3]) << 8) + (uint32(msg[4]) << 16) + (uint32(msg[5]) << 24) // Timestamp. Currently unused.
-
-	msg = msg[6:]
-
 	var toRelay string
-	if len(msg) < 432 {
-		toRelay = "-" // Downlink.
-	} else {
-		toRelay = "+" // Uplink.
+	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))
 	}
 
-	toRelay += fmt.Sprintf("%s;ss=%d;", hex.EncodeToString(msg), rssiDump978)
-	log.Printf("rs_errors=%d, msg=%s\n", rs_errors, toRelay)
-
 	if len(toRelay) > 0 {
 		o, msgtype := parseInput(toRelay)
 		if o != nil && msgtype != 0 {