func DecodeCompressedPositionReport(c string) (geospatial.Point, rune, rune, string, error) {
// Example: =/5L!!<*e7OS]S
var err error
var matches []string
p := geospatial.Point{}
pr := regexp.MustCompile(`[=!]([\\\/])(.{4})(.{4})(.)(..)(.)(.*)$`)
remains := pr.ReplaceAllString(c, "")
p.Time = time.Now()
if matches = pr.FindStringSubmatch(c); len(matches) > 0 {
if len(matches[7]) > 0 {
remains = matches[7]
}
symTable := rune(matches[1][0])
symCode := rune(matches[4][0])
p.Lat, err = DecodeBase91Lat([]byte(matches[2]))
if err != nil {
return p, ' ', ' ', remains, fmt.Errorf("Could not decode compressed latitude: %v\n", err)
}
p.Lon, err = DecodeBase91Lon([]byte(matches[3]))
if err != nil {
return p, ' ', ' ', remains, fmt.Errorf("Could not decode compressed longitude: %v\n", err)
}
// A space in this position indicates that the report includes no altitude, speed/course, or radio range.
if matches[5][0] != ' ' {
// First we look at the Compression Byte ("T" in the spec) and check for a GGA NMEA source.
// If the GGA bits are set, we decode an altitude reading. Otherwise, try to decode a course/
// speed reading or a radio range reading
if (byte(matches[6][0])-33)&0x18 == 0x10 {
// This report has an encoded altitude reading
p.Altitude, err = DecodeBase91Altitude([]byte(matches[5]))
if err != nil {
return p, ' ', ' ', remains, fmt.Errorf("Could not decode compressed altitude: %v\n", err)
}
} else if (byte(matches[5][0])-33) >= 0 && (byte(matches[5][0])-33) <= 89 {
p.Heading, p.Speed, err = DecodeBase91CourseSpeed([]byte(matches[5]))
} else if matches[5][0] == '{' {
p.RadioRange = DecodeBase91RadioRange(byte(matches[5][1]))
}
}
return p, symTable, symCode, remains, nil
}
return p, ' ', ' ', remains, nil
}
func DecodeUncompressedPositionReportWithTimestamp(c string) (geospatial.Point, rune, rune, string, error) {
// Example: @092345z4903.50N/07201.75W>
var matches []string
p := geospatial.Point{}
if len(c) >= 27 {
pr := regexp.MustCompile(`([\/\@])(\d{6})(.)([\d\.\s]{7})([NSns])(.)([\d\.\s]{8})([EWew])(.)(.*)$`)
remains := pr.ReplaceAllString(c, "")
if matches = pr.FindStringSubmatch(c); len(matches) > 0 {
if len(matches[10]) > 0 {
remains = matches[10]
}
if matches[1][0] == '@' {
p.MessageCapable = true
}
switch matches[3][0] {
case 'z':
day, _ := strconv.ParseInt(matches[2][0:2], 10, 0)
hours, _ := strconv.ParseInt(matches[2][2:4], 10, 0)
minutes, _ := strconv.ParseInt(matches[2][4:6], 10, 0)
now := time.Now()
p.Time = time.Date(now.Year(), now.Month(), int(day), int(hours), int(minutes), 0, 0, time.UTC)
case '/':
day, _ := strconv.ParseInt(matches[2][0:2], 10, 0)
hours, _ := strconv.ParseInt(matches[2][2:4], 10, 0)
minutes, _ := strconv.ParseInt(matches[2][4:6], 10, 0)
now := time.Now()
p.Time = time.Date(now.Year(), now.Month(), int(day), int(hours), int(minutes), 0, 0, time.Local)
case 'h':
hours, _ := strconv.ParseInt(matches[2][0:2], 10, 0)
minutes, _ := strconv.ParseInt(matches[2][2:4], 10, 0)
seconds, _ := strconv.ParseInt(matches[2][4:6], 10, 0)
now := time.Now()
p.Time = time.Date(now.Year(), now.Month(), now.Day(), int(hours), int(minutes), int(seconds), 0, time.UTC)
default:
p.Time = time.Now()
}
symTable := rune(matches[6][0])
symCode := rune(matches[9][0])
la1, err := strconv.ParseFloat(matches[4][0:2], 64)
if err != nil {
return p, symTable, symCode, remains, err
}
la2, err := strconv.ParseFloat(matches[4][2:7], 64)
if err != nil {
return p, symTable, symCode, remains, err
}
lat := la1 + la2/60
if matches[5][0] == 'S' {
lat = 0 - lat
}
lo1, err := strconv.ParseFloat(matches[7][0:3], 64)
if err != nil {
return p, symTable, symCode, remains, err
}
lo2, err := strconv.ParseFloat(matches[7][3:8], 64)
if err != nil {
return p, symTable, symCode, remains, err
}
lon := lo1 + lo2/60
if matches[8][0] == 'W' {
lon = 0 - lon
}
p.Lat = lat
p.Lon = lon
return p, symTable, symCode, remains, nil
}
}
return p, ' ', ' ', c, nil
}
func DecodeUncompressedPositionReportWithoutTimestamp(c string) (geospatial.Point, rune, rune, string, error) {
// Example: !4903.50N/07201.75W-
var matches []string
p := geospatial.Point{}
if len(c) >= 20 {
pr := regexp.MustCompile(`([\=\!])([\d\.\s]{7})([NSns])(.)([\d\.\s]{8})([EWew])(.)(.*)$`)
remains := pr.ReplaceAllString(c, "")
p.Time = time.Now()
if matches = pr.FindStringSubmatch(c); len(matches) > 0 {
if len(matches[8]) > 0 {
remains = matches[8]
}
if matches[1][0] == '=' {
p.MessageCapable = true
}
symTable := rune(matches[4][0])
symCode := rune(matches[7][0])
la1, err := strconv.ParseFloat(matches[2][0:2], 64)
if err != nil {
return p, symTable, symCode, remains, err
}
la2, err := strconv.ParseFloat(matches[2][2:7], 64)
if err != nil {
return p, symTable, symCode, remains, err
}
lat := la1 + la2/60
if matches[3][0] == 'S' {
lat = 0 - lat
}
lo1, err := strconv.ParseFloat(matches[5][0:3], 64)
if err != nil {
return p, symTable, symCode, remains, err
}
lo2, err := strconv.ParseFloat(matches[5][3:8], 64)
if err != nil {
return p, symTable, symCode, remains, err
}
lon := lo1 + lo2/60
if matches[6][0] == 'W' {
lon = 0 - lon
}
p.Lat = lat
p.Lon = lon
return p, symTable, symCode, remains, nil
}
}
return p, ' ', ' ', c, nil
}
