feat: Implemented Icom Ethernet CAT control

This commit is contained in:
2026-07-06 17:37:25 +02:00
parent c4ab935d5f
commit 701e8a2c25
7 changed files with 1122 additions and 196 deletions
+643
View File
@@ -0,0 +1,643 @@
package cat
// icomnet.go — the NETWORK transport for the Icom backend. It talks the Icom IP
// remote protocol (the LAN server built into the IC-7610, the one the Icom
// Remote Utility speaks) directly, and presents the tunnelled CI-V byte stream
// as a plain civTransport (Read/Write). So the entire IcomController surface —
// freq/mode, receive-DSP, TX, scope, RIT, CW — runs unchanged over the network;
// only the transport differs. OpsLog thus replaces BOTH the Remote Utility and
// RS-BA1.
//
// The protocol (framing, passcode table, packet offsets, power-on) was
// reimplemented from the public wfview protocol and verified byte-for-byte
// against real Remote-Utility captures. No GPLv3 code is copied.
//
// Three UDP streams exist on the rig (control 50001 / CI-V 50002 / audio 50003);
// this transport uses control + CI-V (audio is not needed for CAT). Connect:
// control: areYouThere→iAmHere→areYouReady→iAmReady → login → token → conninfo
// civ: areYouThere→…→iAmReady → openClose(open) → power-on
// then CI-V flows in data packets. A pump goroutine keeps both streams alive
// (ping replies + idle keepalives) and feeds received CI-V bytes to Read.
import (
"encoding/binary"
"fmt"
"io"
"net"
"strings"
"sync"
"time"
)
var icnLE = binary.LittleEndian
var icnBE = binary.BigEndian
// NewIcomNet builds an (unconnected) Icom backend whose transport is the network
// stream. host is the rig's IP/hostname; user/pass are the rig's Network User1
// credentials. Reuses the whole IcomSerial controller — only `open` differs.
func NewIcomNet(host, user, pass string, civAddr int, digitalDefault string) *IcomSerial {
if civAddr <= 0 || civAddr > 0xFF {
civAddr = 0x98 // IC-7610
}
if digitalDefault == "" {
digitalDefault = "FT8"
}
b := &IcomSerial{
portName: host,
rigAddr: byte(civAddr),
digital: strings.ToUpper(digitalDefault),
model: "Icom",
scopeFixed: true,
}
b.open = func() (civTransport, error) {
if strings.TrimSpace(host) == "" {
return nil, fmt.Errorf("no rig host configured")
}
return dialIcomNet(host, user, pass, "OpsLog", b.rigAddr)
}
return b
}
// icomNet is the connected network transport. It satisfies civTransport.
type icomNet struct {
ctrl *net.UDPConn // control stream (50001)
civ *net.UDPConn // CI-V stream (50002)
cID, cRemote uint32 // control stream ids
vID, vRemote uint32 // civ stream ids
// Tracked-packet sequence + CI-V data sequence. Written only by Write (on the
// CAT goroutine) and during dial — never by the pump — so no lock is needed.
vTracked uint16
vCivSeq uint16
rx chan []byte // CI-V byte chunks from civPump → Read
leftover []byte // partial chunk not yet returned by Read (Read-only)
readTO time.Duration // Read timeout (SetReadTimeout)
// sentBuf keeps recently-sent tracked civ packets (by outer seq) so we can
// answer the rig's UDP retransmit requests. Written by Write (CAT goroutine),
// read by the pumps → guarded by sentMu.
sentMu sync.Mutex
sentBuf map[uint16][]byte
done chan struct{}
closeOnce sync.Once
}
func (n *icomNet) SetReadTimeout(d time.Duration) error { n.readTO = d; return nil }
func (n *icomNet) SetDTR(bool) error { return nil } // n/a on the network
func (n *icomNet) SetRTS(bool) error { return nil }
// Read returns tunnelled CI-V bytes, mimicking a serial port: (0,nil) on
// timeout, (n,nil) with data, (0,err) when the link is closed.
func (n *icomNet) Read(p []byte) (int, error) {
if len(n.leftover) > 0 {
k := copy(p, n.leftover)
n.leftover = n.leftover[k:]
return k, nil
}
to := n.readTO
if to <= 0 {
to = 60 * time.Millisecond
}
select {
case f, ok := <-n.rx:
if !ok {
return 0, io.EOF
}
k := copy(p, f)
if k < len(f) {
n.leftover = append(n.leftover[:0], f[k:]...)
}
return k, nil
case <-time.After(to):
return 0, nil // timeout, no data
case <-n.done:
return 0, io.EOF
}
}
// Write wraps raw CI-V bytes (FE FE … FD) in a data packet and sends them.
func (n *icomNet) Write(p []byte) (int, error) {
if icnTrace {
debugLog.Printf("icom net TX: % X", p)
}
seq := n.vTracked
pkt := icnCivData(seq, n.vID, n.vRemote, n.vCivSeq, p)
n.vTracked++
n.vCivSeq++
n.sentMu.Lock()
n.sentBuf[seq] = pkt
delete(n.sentBuf, seq-256) // keep the buffer bounded (~last 256 packets)
n.sentMu.Unlock()
if _, err := n.civ.Write(pkt); err != nil {
return 0, err
}
return len(p), nil
}
// icnTrace toggles verbose CI-V request/reply logging for diagnosing the
// network transport (temporary).
var icnTrace = true
func (n *icomNet) Close() error {
n.closeOnce.Do(func() {
close(n.done)
// Best-effort clean teardown.
_, _ = n.civ.Write(icnOpenClose(n.vTracked, n.vID, n.vRemote, n.vCivSeq, 0x00)) // close
_, _ = n.civ.Write(icnCtrl(0x05, 0, n.vID, n.vRemote)) // disconnect
_, _ = n.ctrl.Write(icnCtrl(0x05, 0, n.cID, n.cRemote))
_ = n.civ.Close()
_ = n.ctrl.Close()
})
return nil
}
// ctrlPump keeps the control stream (50001) alive: replies to the rig's pings
// and sends idle keepalives. Its own goroutine so it never throttles civPump.
func (n *icomNet) ctrlPump() {
buf := make([]byte, 4096)
lastIdle := time.Now()
for {
select {
case <-n.done:
return
default:
}
_ = n.ctrl.SetReadDeadline(time.Now().Add(100 * time.Millisecond))
if k, err := n.ctrl.Read(buf); err == nil && k >= 16 {
switch icnLE.Uint16(buf[4:]) {
case 0x07: // ping
_, _ = n.ctrl.Write(icnPingReply(buf[:k], n.cID, n.cRemote))
case 0x01: // retransmit request
if k >= 8 {
n.resend(icnLE.Uint16(buf[6:]))
}
}
}
if time.Since(lastIdle) > 150*time.Millisecond {
_, _ = n.ctrl.Write(icnCtrl(0x00, 0, n.cID, n.cRemote))
lastIdle = time.Now()
}
}
}
// civPump owns the CI-V stream (50002): drains it as fast as packets arrive
// (its own goroutine — not throttled by the control reads), replies to pings,
// answers retransmit requests, skips scope frames, and feeds control CI-V bytes
// to Read via n.rx.
func (n *icomNet) civPump() {
buf := make([]byte, 8192)
lastIdle := time.Now()
for {
select {
case <-n.done:
return
default:
}
_ = n.civ.SetReadDeadline(time.Now().Add(100 * time.Millisecond))
if k, err := n.civ.Read(buf); err == nil && k >= 16 {
switch typ := icnLE.Uint16(buf[4:]); {
case typ == 0x07: // ping
_, _ = n.civ.Write(icnPingReply(buf[:k], n.vID, n.vRemote))
case typ == 0x01: // retransmit request — resend that seq
if k >= 8 {
n.resend(icnLE.Uint16(buf[6:]))
}
case typ == 0x00 && k > 0x15 && buf[0x10] == 0xc1: // CI-V data
civBytes := buf[0x15:k]
// Skip scope (0x27) frames: over the network the rig streams the
// panadapter continuously as large frames that would crowd control
// replies out of rx. (Network scope is handled separately.)
if !(len(civBytes) >= 5 && civBytes[4] == 0x27) {
if icnTrace {
debugLog.Printf("icom net RX: % X", civBytes)
}
cp := append([]byte(nil), civBytes...)
select {
case n.rx <- cp:
case <-n.done:
return
default: // buffer full — drop oldest, enqueue newest
select {
case <-n.rx:
default:
}
select {
case n.rx <- cp:
default:
}
}
}
}
}
if time.Since(lastIdle) > 150*time.Millisecond {
_, _ = n.civ.Write(icnCtrl(0x00, 0, n.vID, n.vRemote))
lastIdle = time.Now()
}
}
}
// resend re-transmits a previously-sent tracked CI-V packet the rig asks for
// (its UDP retransmit mechanism). Without this the rig drops the whole session
// after a few seconds when a packet is lost under load.
func (n *icomNet) resend(seq uint16) {
n.sentMu.Lock()
pkt := n.sentBuf[seq]
n.sentMu.Unlock()
if pkt != nil {
_, _ = n.civ.Write(pkt)
}
}
// ------------------------- connect -------------------------
func dialIcomNet(host, user, pass, compName string, rigAddr byte) (*icomNet, error) {
debugLog.Printf("icom net: connecting to %s (user %q, comp %q, rig addr 0x%02X)", host, user, compName, rigAddr)
// ---- control stream (50001): handshake → login → token → conninfo ----
craddr, err := net.ResolveUDPAddr("udp4", net.JoinHostPort(host, "50001"))
if err != nil {
return nil, err
}
ctrl, err := net.DialUDP("udp4", nil, craddr)
if err != nil {
return nil, fmt.Errorf("dial control: %w", err)
}
cID := icnLocalID(ctrl)
cRemote, err := icnHandshake(ctrl, cID)
if err != nil {
_ = ctrl.Close()
debugLog.Printf("icom net: control handshake FAILED (rig unreachable at %s:50001?): %v", host, err)
return nil, fmt.Errorf("control handshake: %w", err)
}
debugLog.Printf("icom net: control link up (rig id 0x%08X) — logging in", cRemote)
var cTracked, cInner uint16 = 1, 1
tokReq := uint16(0x0c77)
_, _ = ctrl.Write(icnLogin(cTracked, cInner, tokReq, cID, cRemote, 0, user, pass, compName))
cTracked++
cInner++
var token uint32
buf := make([]byte, 2048)
deadline := time.Now().Add(5 * time.Second)
for token == 0 && time.Now().Before(deadline) {
p, ok := icnRecv(ctrl, 200, buf)
if !ok {
continue
}
length := icnLE.Uint32(p[0:])
typ := icnLE.Uint16(p[4:])
if typ == 0x00 && length == 0x60 && len(p) >= 0x34 { // login response
token = icnLE.Uint32(p[0x1c:])
if e := icnLE.Uint32(p[0x30:]); e != 0 || token == 0 {
_ = ctrl.Close()
debugLog.Printf("icom net: LOGIN REJECTED (err=0x%08X) — wrong Network User1 ID/Password", e)
return nil, fmt.Errorf("login rejected — check the rig's Network User1 ID/Password")
}
_, _ = ctrl.Write(icnToken(cTracked, cInner, tokReq, cID, cRemote, token))
cTracked++
cInner++
debugLog.Printf("icom net: LOGIN OK, token 0x%08X", token)
} else if typ == 0x07 {
_, _ = ctrl.Write(icnPingReply(p, cID, cRemote))
}
}
if token == 0 {
_ = ctrl.Close()
debugLog.Printf("icom net: login TIMED OUT (no token in 5s) — check host/credentials")
return nil, fmt.Errorf("login timed out (no token) — check host/credentials")
}
// Learn the rig's MAC from its conninfo push (144B) to echo in our conninfo.
var rigMAC []byte
macEnd := time.Now().Add(1200 * time.Millisecond)
for time.Now().Before(macEnd) {
p, ok := icnRecv(ctrl, 150, buf)
if !ok {
continue
}
if len(p) >= 0x30 && icnLE.Uint32(p[0:]) == 0x90 { // 144-byte conninfo push
rigMAC = append([]byte(nil), p[0x2a:0x30]...)
}
if icnLE.Uint16(p[4:]) == 0x07 {
_, _ = ctrl.Write(icnPingReply(p, cID, cRemote))
}
if rigMAC != nil {
break
}
}
if rigMAC == nil {
rigMAC = make([]byte, 6)
}
_, _ = ctrl.Write(icnConnInfo(cTracked, cInner, tokReq, cID, cRemote, token, user, rigMAC, 50002, 50003))
cTracked++
cInner++
drainEnd := time.Now().Add(500 * time.Millisecond)
for time.Now().Before(drainEnd) {
if p, ok := icnRecv(ctrl, 100, buf); ok && icnLE.Uint16(p[4:]) == 0x07 {
_, _ = ctrl.Write(icnPingReply(p, cID, cRemote))
}
}
// ---- CI-V stream (50002): bind LOCAL :50002 (the announced civport) ----
vraddr, err := net.ResolveUDPAddr("udp4", net.JoinHostPort(host, "50002"))
if err != nil {
_ = ctrl.Close()
return nil, err
}
debugLog.Printf("icom net: conninfo sent (rig mac % X) — opening CI-V stream", rigMAC)
civ, err := net.DialUDP("udp4", &net.UDPAddr{Port: 50002}, vraddr)
if err != nil {
_ = ctrl.Close()
debugLog.Printf("icom net: cannot bind local :50002 — the Icom Remote Utility is probably still running: %v", err)
return nil, fmt.Errorf("dial CI-V (local :50002 — is the Icom Remote Utility still running?): %w", err)
}
vID := icnLocalID(civ)
vRemote, err := icnHandshake(civ, vID)
if err != nil {
_ = civ.Close()
_ = ctrl.Close()
debugLog.Printf("icom net: CI-V handshake FAILED: %v", err)
return nil, fmt.Errorf("CI-V handshake: %w", err)
}
debugLog.Printf("icom net: CI-V link up — sending power-on, waiting for the rig to boot (~15s)")
// Bigger receive buffers so a burst of scope/CI-V packets doesn't overflow
// (dropped packets → the rig's retransmit requests → session drop).
_ = ctrl.SetReadBuffer(1 << 20)
_ = civ.SetReadBuffer(1 << 20)
n := &icomNet{
ctrl: ctrl, civ: civ,
cID: cID, cRemote: cRemote, vID: vID, vRemote: vRemote,
vTracked: 1, vCivSeq: 1,
rx: make(chan []byte, 256),
sentBuf: make(map[uint16][]byte),
done: make(chan struct{}),
}
// openClose(open) starts the CI-V data flow.
ocPkt := icnOpenClose(n.vTracked, vID, vRemote, n.vCivSeq, 0x04)
n.sentBuf[n.vTracked] = ocPkt
_, _ = civ.Write(ocPkt)
n.vTracked++
n.vCivSeq++
// Power-on (the rig may be in standby — it NG's every command until on):
// an FE wake preamble then FE FE <rig> E0 18 01 FD. Harmless if already on.
po := make([]byte, 0, 32)
for i := 0; i < 25; i++ {
po = append(po, 0xFE)
}
po = append(po, 0xFE, 0xFE, rigAddr, 0xE0, 0x18, 0x01, 0xFD)
poPkt := icnCivData(n.vTracked, vID, vRemote, n.vCivSeq, po)
n.sentBuf[n.vTracked] = poPkt
_, _ = civ.Write(poPkt)
n.vTracked++
n.vCivSeq++
// Wait for the rig to finish booting: a rig woken from standby NG's/ignores
// commands for ~10-15 s. Poll read-freq (keeping both streams alive) until it
// answers, so Connect only returns a READY link — otherwise the manager's
// read-timeouts would flap the connection during boot. Give up after 25 s and
// return anyway (the rig may already be on and just quiet).
if n.waitReady(rigAddr, 25*time.Second) {
debugLog.Printf("icom net: rig is READY (answered read-freq) — connection up ✓")
} else {
debugLog.Printf("icom net: boot wait timed out (25s, no freq reply) — proceeding anyway")
}
go n.ctrlPump()
go n.civPump()
return n, nil
}
// waitReady polls read-freq until the rig replies (booted) or timeout, replying
// to pings and sending idle keepalives so the session stays up. Runs before the
// pump goroutine starts, so it owns the socket reads.
func (n *icomNet) waitReady(rigAddr byte, timeout time.Duration) bool {
cbuf := make([]byte, 4096)
vbuf := make([]byte, 4096)
readFreq := []byte{0xFE, 0xFE, rigAddr, 0xE0, 0x03, 0xFD}
end := time.Now().Add(timeout)
var lastPoll, lastIdle time.Time
for time.Now().Before(end) {
if p, ok := icnRecv(n.ctrl, 25, cbuf); ok && icnLE.Uint16(p[4:]) == 0x07 {
_, _ = n.ctrl.Write(icnPingReply(p, n.cID, n.cRemote))
}
if p, ok := icnRecv(n.civ, 25, vbuf); ok {
typ := icnLE.Uint16(p[4:])
if typ == 0x07 {
_, _ = n.civ.Write(icnPingReply(p, n.vID, n.vRemote))
} else if typ == 0x00 && len(p) > 0x15 && p[0x10] == 0xc1 {
f := p[0x15:]
// A frequency reply from the rig: FE FE E0 <rig> 03 …
if len(f) >= 6 && f[0] == 0xFE && f[1] == 0xFE && f[3] == rigAddr && f[4] == 0x03 {
return true
}
}
}
if time.Since(lastIdle) > 180*time.Millisecond {
_, _ = n.ctrl.Write(icnCtrl(0x00, 0, n.cID, n.cRemote))
_, _ = n.civ.Write(icnCtrl(0x00, 0, n.vID, n.vRemote))
lastIdle = time.Now()
}
if time.Since(lastPoll) > 1000*time.Millisecond {
_, _ = n.civ.Write(icnCivData(n.vTracked, n.vID, n.vRemote, n.vCivSeq, readFreq))
n.vTracked++
n.vCivSeq++
lastPoll = time.Now()
}
}
return false
}
// icnHandshake: areYouThere(seq0) → iAmHere → areYouReady(seq1) → iAmReady.
func icnHandshake(c *net.UDPConn, myID uint32) (uint32, error) {
buf := make([]byte, 2048)
_, _ = c.Write(icnCtrl(0x03, 0, myID, 0))
var remoteID uint32
deadline := time.Now().Add(4 * time.Second)
lastTry := time.Now()
for time.Now().Before(deadline) {
p, ok := icnRecv(c, 200, buf)
if !ok {
if remoteID == 0 && time.Since(lastTry) > 500*time.Millisecond {
_, _ = c.Write(icnCtrl(0x03, 0, myID, 0))
lastTry = time.Now()
}
continue
}
typ := icnLE.Uint16(p[4:])
sentid := icnLE.Uint32(p[8:])
switch typ {
case 0x04: // iAmHere
remoteID = sentid
_, _ = c.Write(icnCtrl(0x06, 1, myID, remoteID))
case 0x06: // iAmReady
if remoteID != 0 {
return remoteID, nil
}
case 0x07: // ping
_, _ = c.Write(icnPingReply(p, myID, remoteID))
}
}
return 0, fmt.Errorf("handshake timeout")
}
func icnRecv(c *net.UDPConn, ms int, buf []byte) ([]byte, bool) {
_ = c.SetReadDeadline(time.Now().Add(time.Duration(ms) * time.Millisecond))
k, err := c.Read(buf)
if err != nil || k < 16 {
return nil, false
}
return buf[:k], true
}
func icnLocalID(c *net.UDPConn) uint32 {
a := c.LocalAddr().(*net.UDPAddr)
ip := a.IP.To4()
if ip == nil {
ip = []byte{192, 168, 0, 1}
}
return uint32(ip[0])<<24 | uint32(ip[1])<<16 | uint32(uint16(a.Port))
}
// ------------------------- packet builders -------------------------
// (offsets verified vs wfview structs + real captures)
func icnCtrl(typ, seq uint16, sentid, rcvdid uint32) []byte {
b := make([]byte, 16)
icnLE.PutUint32(b[0:], 0x10)
icnLE.PutUint16(b[4:], typ)
icnLE.PutUint16(b[6:], seq)
icnLE.PutUint32(b[8:], sentid)
icnLE.PutUint32(b[12:], rcvdid)
return b
}
func icnPingReply(pkt []byte, myID, remoteID uint32) []byte {
r := append([]byte(nil), pkt...)
if len(r) >= 17 {
icnLE.PutUint32(r[8:], myID)
icnLE.PutUint32(r[12:], remoteID)
r[16] = 0x01
}
return r
}
func icnLogin(seq, innerSeq, tokReq uint16, sentid, rcvdid, token uint32, user, pass, name string) []byte {
b := make([]byte, 0x80)
icnLE.PutUint32(b[0:], 0x80)
icnLE.PutUint16(b[6:], seq)
icnLE.PutUint32(b[8:], sentid)
icnLE.PutUint32(b[12:], rcvdid)
icnBE.PutUint32(b[0x10:], 0x80-0x10)
b[0x14] = 0x01
b[0x15] = 0x00
icnBE.PutUint16(b[0x16:], innerSeq)
icnLE.PutUint16(b[0x1a:], tokReq)
icnLE.PutUint32(b[0x1c:], token)
copy(b[0x40:0x50], icnPasscode(user))
copy(b[0x50:0x60], icnPasscode(pass))
nm := name
if len(nm) > 16 {
nm = nm[:16]
}
copy(b[0x60:0x70], []byte(nm))
return b
}
func icnToken(seq, innerSeq, tokReq uint16, sentid, rcvdid, token uint32) []byte {
b := make([]byte, 0x40)
icnLE.PutUint32(b[0:], 0x40)
icnLE.PutUint16(b[6:], seq)
icnLE.PutUint32(b[8:], sentid)
icnLE.PutUint32(b[12:], rcvdid)
icnBE.PutUint32(b[0x10:], 0x40-0x10)
b[0x14] = 0x01
b[0x15] = 0x02
icnBE.PutUint16(b[0x16:], innerSeq)
icnLE.PutUint16(b[0x1a:], tokReq)
icnLE.PutUint32(b[0x1c:], token)
return b
}
func icnConnInfo(seq, innerSeq, tokReq uint16, sentid, rcvdid, token uint32, user string, rigMAC []byte, civPort, audioPort uint16) []byte {
b := make([]byte, 0x90)
icnLE.PutUint32(b[0:], 0x90)
icnLE.PutUint16(b[6:], seq)
icnLE.PutUint32(b[8:], sentid)
icnLE.PutUint32(b[12:], rcvdid)
icnBE.PutUint32(b[0x10:], 0x90-0x10)
b[0x14] = 0x01
b[0x15] = 0x03 // requesttype = conninfo / open streams
icnBE.PutUint16(b[0x16:], innerSeq)
icnLE.PutUint16(b[0x1a:], tokReq)
icnLE.PutUint32(b[0x1c:], token)
icnLE.PutUint16(b[0x27:], 0x8010) // commoncap
copy(b[0x2a:0x30], rigMAC)
copy(b[0x40:0x60], []byte("IC-7610"))
copy(b[0x60:0x70], icnPasscode(user))
b[0x70] = 0x00 // rxenable (audio off — CI-V only)
b[0x71] = 0x00 // txenable
b[0x72] = 0x10 // rxcodec
b[0x73] = 0x04 // txcodec
icnBE.PutUint32(b[0x74:], 16000)
icnBE.PutUint32(b[0x78:], 8000)
icnBE.PutUint32(b[0x7c:], uint32(civPort))
icnBE.PutUint32(b[0x80:], uint32(audioPort))
icnBE.PutUint32(b[0x84:], 100)
b[0x88] = 0x00
return b
}
func icnOpenClose(seq uint16, sentid, rcvdid uint32, civSeq uint16, magic byte) []byte {
b := make([]byte, 0x16)
icnLE.PutUint32(b[0:], 0x16)
icnLE.PutUint16(b[6:], seq)
icnLE.PutUint32(b[8:], sentid)
icnLE.PutUint32(b[12:], rcvdid)
icnLE.PutUint16(b[0x10:], 0x01c0)
icnBE.PutUint16(b[0x13:], civSeq)
b[0x15] = magic
return b
}
func icnCivData(seq uint16, sentid, rcvdid uint32, civSeq uint16, civ []byte) []byte {
nn := 0x15 + len(civ)
b := make([]byte, nn)
icnLE.PutUint32(b[0:], uint32(nn))
icnLE.PutUint16(b[6:], seq)
icnLE.PutUint32(b[8:], sentid)
icnLE.PutUint32(b[12:], rcvdid)
b[0x10] = 0xc1
icnLE.PutUint16(b[0x11:], uint16(len(civ)))
icnBE.PutUint16(b[0x13:], civSeq)
copy(b[0x15:], civ)
return b
}
// icnPasscodeSeq — Icom's obfuscation table (values at index 0x20..0x7e).
// VERIFIED: user "f6bgc" → 3F 65 50 25 55 (matches the capture).
var icnPasscodeSeq = [256]byte{
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0x47, 0x5d, 0x4c, 0x42, 0x66, 0x20, 0x23, 0x46, 0x4e, 0x57, 0x45, 0x3d, 0x67, 0x76, 0x60, 0x41, 0x62, 0x39, 0x59, 0x2d, 0x68, 0x7e,
0x7c, 0x65, 0x7d, 0x49, 0x29, 0x72, 0x73, 0x78, 0x21, 0x6e, 0x5a, 0x5e, 0x4a, 0x3e, 0x71, 0x2c, 0x2a, 0x54, 0x3c, 0x3a, 0x63, 0x4f,
0x43, 0x75, 0x27, 0x79, 0x5b, 0x35, 0x70, 0x48, 0x6b, 0x56, 0x6f, 0x34, 0x32, 0x6c, 0x30, 0x61, 0x6d, 0x7b, 0x2f, 0x4b, 0x64, 0x38,
0x2b, 0x2e, 0x50, 0x40, 0x3f, 0x55, 0x33, 0x37, 0x25, 0x77, 0x24, 0x26, 0x74, 0x6a, 0x28, 0x53, 0x4d, 0x69, 0x22, 0x5c, 0x44, 0x31,
0x36, 0x58, 0x3b, 0x7a, 0x51, 0x5f, 0x52,
}
func icnPasscode(s string) []byte {
out := make([]byte, 0, len(s))
for i := 0; i < len(s) && i < 16; i++ {
p := int(s[i]) + i
if p > 126 {
p = 32 + p%127
}
out = append(out, icnPasscodeSeq[p])
}
return out
}