kopia lustrzana https://github.com/cyoung/stratux
Working NEXRAD decode.
Christopher Young
rodzic
0db905904f
commit
f1ea6bd1a6
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@ -0,0 +1,213 @@
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package main
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import (
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"fmt"
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"./uatparse"
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"strconv"
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"os"
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"bufio"
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)
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// Most adapted from extract_nexrad.c
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const (
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BLOCK_WIDTH = float64(48.0/60.0)
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WIDE_BLOCK_WIDTH = float64(96.0/60.0)
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BLOCK_HEIGHT = float64(4.0/60.0)
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BLOCK_THRESHOLD = 405000
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BLOCKS_PER_RING = 450
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)
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type NEXRADFrame struct {
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radar_type uint32
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ts string
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scale int
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latNorth float64
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lonWest float64
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height float64
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width float64
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intensity []uint8 // Really only 4-bit values.
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}
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func block_location(block_num int, ns_flag bool, scale_factor int) (float64, float64, float64, float64) {
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var realScale float64
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if scale_factor == 1 {
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realScale = float64(5.0)
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} else if scale_factor == 2 {
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realScale = float64(9.0)
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} else {
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realScale = float64(1.0)
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}
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if block_num >= BLOCK_THRESHOLD {
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block_num = block_num & ^1
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}
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raw_lat := float64(BLOCK_HEIGHT * float64(int(float64(block_num) / float64(BLOCKS_PER_RING))))
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raw_lon := float64(block_num % BLOCKS_PER_RING) * BLOCK_WIDTH
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var lonSize float64
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if block_num >= BLOCK_THRESHOLD {
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lonSize = WIDE_BLOCK_WIDTH * realScale
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} else {
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lonSize = BLOCK_WIDTH * realScale
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}
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latSize := BLOCK_HEIGHT * realScale
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if ns_flag { // Southern hemisphere.
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raw_lat = 0 - raw_lat
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} else {
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raw_lat = raw_lat + BLOCK_HEIGHT
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}
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/*
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if raw_lon > 180.0 {
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raw_lon = raw_lon - 360.0
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}*/
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return raw_lat, raw_lon, latSize, lonSize
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}
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func decode_nexrad(f *uatparse.UATFrame) []NEXRADFrame {
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ret := make([]NEXRADFrame, 0)
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rle_flag := (uint32(f.FISB_data[0]) & 0x80) != 0
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ns_flag := (uint32(f.FISB_data[0]) & 0x40) != 0
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block_num := ((int(f.FISB_data[0]) & 0x0f) << 16) | (int(f.FISB_data[1]) << 8) | (int(f.FISB_data[2]))
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scale_factor := (int(f.FISB_data[0]) & 0x30) >> 4
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if rle_flag { // Single bin, RLE encoded.
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lat, lon, h, w := block_location(block_num, ns_flag, scale_factor)
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var tmp NEXRADFrame
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tmp.radar_type = f.Product_id
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tmp.ts = strconv.Itoa(int(f.FISB_hours)) + ":" + strconv.Itoa(int(f.FISB_minutes))
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tmp.scale = scale_factor
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tmp.latNorth = lat
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tmp.lonWest = lon
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tmp.height = h
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tmp.width = w
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tmp.intensity = make([]uint8, 0)
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intensityData := f.FISB_data[3:]
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for _, v := range intensityData {
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intensity := uint8(v) & 0x7;
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runlength := (uint8(v) >> 3) + 1
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for runlength > 0 {
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tmp.intensity = append(tmp.intensity, intensity)
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runlength--
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}
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}
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ret = append(ret, tmp)
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} else {
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var row_start int
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var row_size int
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if block_num >= 405000 {
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row_start = block_num - ((block_num - 405000) % 225)
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row_size = 225
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} else {
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row_start = block_num - (block_num % 450)
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row_size = 450
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}
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row_offset := block_num - row_start
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L := int(f.FISB_data[3] & 15)
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for i := 0; i < L; i++ {
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var bb int
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if i == 0 {
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bb = (int(f.FISB_data[3]) & 0xF0) | 0x08
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} else {
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bb = int(f.FISB_data[i+3])
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}
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for j := 0; j < 8; j++ {
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if bb & (1 << uint(j)) != 0 {
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row_x := (row_offset + 8*i + j - 3) % row_size
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bn := row_start + row_x
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lat, lon, h, w := block_location(bn, ns_flag, scale_factor)
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var tmp NEXRADFrame
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tmp.radar_type = f.Product_id
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tmp.ts = strconv.Itoa(int(f.FISB_hours)) + ":" + strconv.Itoa(int(f.FISB_minutes))
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tmp.scale = scale_factor
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tmp.latNorth = lat
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tmp.lonWest = lon
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tmp.height = h
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tmp.width = w
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tmp.intensity = make([]uint8, 0)
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for k := 0; k < 128; k++ {
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z := uint8(0)
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if f.Product_id == 64 {
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z = 1
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}
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tmp.intensity = append(tmp.intensity, z)
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}
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ret = append(ret, tmp)
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}
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}
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}
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}
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return ret
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}
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func parseInput(buf string) []NEXRADFrame {
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ret := make([]NEXRADFrame, 0)
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uatmsg, err := uatparse.New(buf)
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if err != nil {
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return ret
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}
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uatmsg.DecodeUplink()
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for _, uatframe := range uatmsg.Frames {
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if uatframe.Product_id != 63 && uatframe.Product_id != 64 { // It's neither CONUS nor Regional NEXRAD.
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continue
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}
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p := decode_nexrad(uatframe)
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if p != nil {
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ret = append(ret, p...)
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}
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}
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return ret
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}
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func main() {
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if len(os.Args) < 2 {
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fmt.Printf("%s <uat log>\n", os.Args[0])
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return
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}
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fd, err := os.Open(os.Args[1])
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if err != nil {
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fmt.Printf("can't open file: %s\n", err.Error())
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return
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}
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reader := bufio.NewReader(fd)
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for {
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buf, err := reader.ReadString('\n')
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if err != nil {
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fmt.Printf("lost stdin.\n")
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break
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}
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z := parseInput(buf)
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for _, zz := range z {
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n := "Regional"
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if zz.radar_type == 64 {
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n = "CONUS"
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}
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fmt.Printf("NEXRAD %s %s %d %.0f %.0f %.0f %.0f ", n, zz.ts, zz.scale, zz.latNorth * 60, zz.lonWest * 60, zz.height * 60, zz.width * 60)
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for _, intens := range zz.intensity {
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fmt.Printf("%d", intens)
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}
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fmt.Printf("\n")
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}
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}
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}
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@ -27,7 +27,10 @@ const (
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)
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type UATFrame struct {
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raw_data []byte
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Raw_data []byte
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FISB_data []byte
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FISB_hours uint32
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FISB_minutes uint32
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frame_length uint32
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Frame_type uint32
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@ -81,11 +84,7 @@ func dlac_decode(data []byte, data_len uint32) string {
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func (f *UATFrame) decodeInfoFrame() {
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f.Product_id = ((uint32(f.raw_data[0]) & 0x1f) << 6) | (uint32(f.raw_data[1]) >> 2)
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if f.Product_id != 413 { // FIXME.
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return
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}
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f.Product_id = ((uint32(f.Raw_data[0]) & 0x1f) << 6) | (uint32(f.Raw_data[1]) >> 2)
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if f.Frame_type != 0 {
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return // Not FIS-B.
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@ -94,7 +93,7 @@ func (f *UATFrame) decodeInfoFrame() {
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return // Too short for FIS-B.
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}
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t_opt := ((uint32(f.raw_data[1]) & 0x01) << 1) | (uint32(f.raw_data[2]) >> 7)
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t_opt := ((uint32(f.Raw_data[1]) & 0x01) << 1) | (uint32(f.Raw_data[2]) >> 7)
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if t_opt != 0 { //FIXME.
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// fmt.Printf("don't know time format %d\n", t_opt)
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@ -102,11 +101,16 @@ func (f *UATFrame) decodeInfoFrame() {
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return
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}
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/* fisb_hours := (uint32(data[2]) & 0x7c) >> 2
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fisb_minutes := ((uint32(data[2]) & 0x03) << 4) | (uint32(data[3]) >> 4)
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*/
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f.FISB_hours = (uint32(f.Raw_data[2]) & 0x7c) >> 2
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f.FISB_minutes = ((uint32(f.Raw_data[2]) & 0x03) << 4) | (uint32(f.Raw_data[3]) >> 4)
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fisb_length := f.frame_length - 4
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fisb_data := f.raw_data[4:]
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fisb_data := f.Raw_data[4:]
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f.FISB_data = fisb_data
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if f.Product_id != 413 { // Doesn't have text data that we'd be interested in, so we're done.
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return
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}
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p := dlac_decode(fisb_data, fisb_length)
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ret := make([]string, 0)
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@ -178,7 +182,7 @@ func (u *UATMsg) DecodeUplink() error {
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data = data[2 : frame_length+2]
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thisFrame := new(UATFrame)
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thisFrame.raw_data = data
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thisFrame.Raw_data = data
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thisFrame.frame_length = frame_length
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thisFrame.Frame_type = frame_type
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