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Replaced NEXRAD processing.
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@cyoung
cyoung committed Oct 24, 2016
1 parent 386be11 commit b829e22
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Showing 2 changed files with 150 additions and 121 deletions.
147 changes: 147 additions & 0 deletions uatparse/nexrad.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,147 @@
package uatparse

import ()

const (
BLOCK_WIDTH = float64(48.0 / 60.0)
WIDE_BLOCK_WIDTH = float64(96.0 / 60.0)
BLOCK_HEIGHT = float64(4.0 / 60.0)
BLOCK_THRESHOLD = 405000
BLOCKS_PER_RING = 450
)

type NEXRADBlock struct {
radar_type uint32
scale int
latNorth float64
lonWest float64
height float64
width float64
intensity []uint8 // Really only 4-bit values.
}

func block_location(block_num int, ns_flag bool, scale_factor int) (float64, float64, float64, float64) {
var realScale float64
if scale_factor == 1 {
realScale = float64(5.0)
} else if scale_factor == 2 {
realScale = float64(9.0)
} else {
realScale = float64(1.0)
}

if block_num >= BLOCK_THRESHOLD {
block_num = block_num & ^1
}

raw_lat := float64(BLOCK_HEIGHT * float64(int(float64(block_num)/float64(BLOCKS_PER_RING))))
raw_lon := float64(block_num%BLOCKS_PER_RING) * BLOCK_WIDTH

var lonSize float64
if block_num >= BLOCK_THRESHOLD {
lonSize = WIDE_BLOCK_WIDTH * realScale
} else {
lonSize = BLOCK_WIDTH * realScale
}

latSize := BLOCK_HEIGHT * realScale

if ns_flag { // Southern hemisphere.
raw_lat = 0 - raw_lat
} else {
raw_lat = raw_lat + BLOCK_HEIGHT
}

if raw_lon > 180.0 {
raw_lon = raw_lon - 360.0
}

return raw_lat, raw_lon, latSize, lonSize

}

func (f *UATFrame) decodeNexradFrame() {
if len(f.FISB_data) < 4 { // Short read.
return
}

rle_flag := (uint32(f.FISB_data[0]) & 0x80) != 0
ns_flag := (uint32(f.FISB_data[0]) & 0x40) != 0
block_num := ((int(f.FISB_data[0]) & 0x0f) << 16) | (int(f.FISB_data[1]) << 8) | (int(f.FISB_data[2]))
scale_factor := (int(f.FISB_data[0]) & 0x30) >> 4

if rle_flag { // Single bin, RLE encoded.
lat, lon, h, w := block_location(block_num, ns_flag, scale_factor)
var tmp NEXRADBlock
tmp.radar_type = f.Product_id
tmp.scale = scale_factor
tmp.latNorth = lat
tmp.lonWest = lon
tmp.height = h
tmp.width = w
tmp.intensity = make([]uint8, 0)

intensityData := f.FISB_data[3:]
for _, v := range intensityData {
intensity := uint8(v) & 0x7
runlength := (uint8(v) >> 3) + 1
for runlength > 0 {
tmp.intensity = append(tmp.intensity, intensity)
runlength--
}
}
f.NEXRAD = []NEXRADBlock{tmp}
} else {
var row_start int
var row_size int
if block_num >= 405000 {
row_start = block_num - ((block_num - 405000) % 225)
row_size = 225
} else {
row_start = block_num - (block_num % 450)
row_size = 450
}

row_offset := block_num - row_start

L := int(f.FISB_data[3] & 15)

if len(f.FISB_data) < L+3 { // Short read.
return
}

for i := 0; i < L; i++ {
var bb int
if i == 0 {
bb = (int(f.FISB_data[3]) & 0xF0) | 0x08
} else {
bb = int(f.FISB_data[i+3])
}

for j := 0; j < 8; j++ {
if bb&(1<<uint(j)) != 0 {
row_x := (row_offset + 8*i + j - 3) % row_size
bn := row_start + row_x
lat, lon, h, w := block_location(bn, ns_flag, scale_factor)
var tmp NEXRADBlock
tmp.radar_type = f.Product_id
tmp.scale = scale_factor
tmp.latNorth = lat
tmp.lonWest = lon
tmp.height = h
tmp.width = w
tmp.intensity = make([]uint8, 0)
for k := 0; k < 128; k++ {
z := uint8(0)
if f.Product_id == 64 {
z = 1
}
tmp.intensity = append(tmp.intensity, z)
}
f.NEXRAD = append(f.NEXRAD, tmp)
}
}
}
}
return ret
}
124 changes: 3 additions & 121 deletions uatparse/uatparse.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -10,8 +10,6 @@ import (
"strings"
)

var elementIdentifier byte

const (
UPLINK_BLOCK_DATA_BITS = 576
UPLINK_BLOCK_BITS = (UPLINK_BLOCK_DATA_BITS + 160)
Expand All @@ -27,8 +25,6 @@ const (
// assume 6 byte frames: 2 header bytes, 4 byte payload
// (TIS-B heartbeat with one address, or empty FIS-B APDU)
UPLINK_MAX_INFO_FRAMES = (424 / 6)
COLS_PER_BIN = 32
ROWS_PER_BIN = 4

dlac_alpha = "\x03ABCDEFGHIJKLMNOPQRSTUVWXYZ\x1A\t\x1E\n| !\"#$%&'()*+,-./0123456789:;<=>?"
)
Expand Down Expand Up @@ -66,6 +62,9 @@ type UATFrame struct {
RecordFormat uint8
ReportStart string
ReportEnd string

// For NEXRAD.
NEXRAD []NEXRADBlock
}

type UATMsg struct {
Expand Down Expand Up @@ -192,123 +191,6 @@ func formatDLACData(p string) []string {
return ret
}

func (f *UATFrame) decodeNexradFrame() {
ret := make([]string, 0)
builder := make([]string, 0)

if len(f.FISB_data) < int(f.FISB_length) {
return
}
mEmpty := make([]int32, 1)
mData := make([]int32, COLS_PER_BIN*ROWS_PER_BIN)
elementIdentifier := f.FISB_data[0] & 0x80
mBlock := uint32(f.FISB_data[0]&0x0f) << 16
mBlock = mBlock | uint32(f.FISB_data[1])<<8
mBlock = mBlock | uint32(f.FISB_data[2])
index := 3
// Make 32 * 4 array
if elementIdentifier != 0 {
// Clear the array
for c := 0; c < (COLS_PER_BIN * ROWS_PER_BIN); c++ {
mData[c] = 0
}
j := 0
for index < int(f.FISB_length) {
numberOfBins := ((f.FISB_data[index] & 0xf8) >> 3) + 1
for i := 0; i < int(numberOfBins); i++ {
if j >= int(COLS_PER_BIN*ROWS_PER_BIN) {
return
}
mData[j] = int32(f.FISB_data[index] & 0x07)
j++
}
index++
}
} else {
bitmapLen := int32(f.FISB_data[index] & 0x0f)
// Start with 1 element

mEmpty[0] = int32(mBlock)
if (f.FISB_data[index] & 0x10) != 0 {
mEmpty = append(mEmpty, int32(mBlock+1))
}
if (f.FISB_data[index] & 0x20) != 0 {
mEmpty = append(mEmpty, int32(mBlock+2))
}
if (f.FISB_data[index] & 0x30) != 0 {
mEmpty = append(mEmpty, int32(mBlock+3))
}
if (f.FISB_data[index] & 0x40) != 0 {
mEmpty = append(mEmpty, int32(mBlock+4))
}
for i := 1; i < int(bitmapLen); i++ {
if (f.FISB_data[index+i] & 0x01) != 0 {
mEmpty = append(mEmpty, int32(mBlock+uint32(i)*8-3))
}
if (f.FISB_data[index+i] & 0x02) != 0 {
mEmpty = append(mEmpty, int32(mBlock+uint32(i)*8-2))
}
if (f.FISB_data[index+i] & 0x04) != 0 {
mEmpty = append(mEmpty, int32(mBlock+uint32(i)*8-1))
}
if (f.FISB_data[index+i] & 0x08) != 0 {
mEmpty = append(mEmpty, int32(mBlock+uint32(i)*8-0))
}
if (f.FISB_data[index+i] & 0x10) != 0 {
mEmpty = append(mEmpty, int32(mBlock+uint32(i)*8+1))
}
if (f.FISB_data[index+i] & 0x20) != 0 {
mEmpty = append(mEmpty, int32(mBlock+uint32(i)*8+2))
}
if (f.FISB_data[index+i] & 0x40) != 0 {
mEmpty = append(mEmpty, int32(mBlock+uint32(i)*8+3))
}
if (f.FISB_data[index+i] & 0x80) != 0 {
mEmpty = append(mEmpty, int32(mBlock+uint32(i)*8+4))
}
}
}
log.Printf("NEXRAD: elementIdentifier %d mBlock %d\n", elementIdentifier, mBlock)
log.Printf("NEXRAD: mEmpty %d mData %d\n", mEmpty, mData)
// field 1 - NEXRAD
builder = append(builder, "NEXRAD")
// CONUS
if f.Product_id == 63 {
builder = append(builder, "0")
} else {
builder = append(builder, "1")
}
// Field 3 block
builder = append(builder, fmt.Sprintf("%d", mBlock))
// Field 4 Columns
builder = append(builder, fmt.Sprintf("%d", COLS_PER_BIN))
// Field 5 Rows
builder = append(builder, fmt.Sprintf("%d", ROWS_PER_BIN))
if elementIdentifier != 0 {
builder = append(builder, "1")
bin := ""
for br := range mData {
bin = bin + fmt.Sprintf("%d,", mData[br])
}
if bin[len(bin)-1] == ',' {
bin = bin[0 : len(bin)-1]
}
builder = append(builder, bin)
} else {
builder = append(builder, "0")
bin2 := ""
for be := range mEmpty {
bin2 = bin2 + fmt.Sprintf("%d,", mEmpty[be])
}
if bin2[len(bin2)-1] == ',' {
bin2 = bin2[0 : len(bin2)-1]
}
builder = append(builder, bin2)
}
ret = append(ret, fmt.Sprintf(strings.Join(builder, " ")))
f.Text_data = ret
}

// Whole frame contents is DLAC encoded text.
func (f *UATFrame) decodeTextFrame() {
if len(f.FISB_data) < int(f.FISB_length) {
Expand Down

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