feat: cw decoder

app.go

@@ -378,6 +378,8 @@ type App struct {
 	ubFollowStop        chan struct{}     // stops the "follow frequency" loop; nil when off
 	audioMgr            *audio.Manager
 	qsoRec              *audio.Recorder // continuous QSO recorder (rolling pre-roll)
+	cwMu                sync.Mutex      // guards the CW decoder lifecycle
+	cwStop              chan struct{}   // stops the CW decoder capture loop; nil when off
 	dvkRecSlot          int             // slot currently being recorded (DVKStartRecord → DVKStopRecord)
 	dvkPttKeyed         bool            // we keyed PTT for a voice message; unkey when it ends
 	pttMu               sync.Mutex

app_cw.go

@@ -0,0 +1,82 @@
+package main
+
+import (
+	"fmt"
+
+	"hamlog/internal/applog"
+	"hamlog/internal/audio"
+	"hamlog/internal/cwdecode"
+
+	wruntime "github.com/wailsapp/wails/v2/pkg/runtime"
+)
+
+// CW decoder: taps the RX audio device (the same "From radio" capture the DVK
+// and QSO recorder use) and streams decoded Morse text to the UI. It is started
+// only by the frontend, and only while the entry mode is CW.
+
+// StartCWDecoder begins decoding CW from the configured RX audio device. The
+// frontend calls this when the decoder toggle is on AND the mode is CW. Safe to
+// call repeatedly; a second call is a no-op while already running.
+func (a *App) StartCWDecoder() error {
+	a.cwMu.Lock()
+	defer a.cwMu.Unlock()
+	if a.cwStop != nil {
+		return nil // already running
+	}
+	dev := ""
+	if a.settings != nil {
+		dev, _ = a.settings.Get(a.ctx, keyAudioFromRadio)
+	}
+	if dev == "" {
+		return fmt.Errorf("no RX audio device configured (set \"From radio\" in Audio settings)")
+	}
+
+	dec := cwdecode.New(audio.SampleRate,
+		func(text string) {
+			if a.ctx != nil {
+				wruntime.EventsEmit(a.ctx, "cw:text", text)
+			}
+		},
+		func(st cwdecode.Status) {
+			if a.ctx != nil {
+				wruntime.EventsEmit(a.ctx, "cw:status", st)
+			}
+		},
+	)
+
+	stop := make(chan struct{})
+	a.cwStop = stop
+	go func() {
+		if err := audio.StreamCapture(dev, stop, dec.Process); err != nil {
+			applog.Printf("cw: capture failed: %v", err)
+			if a.ctx != nil {
+				wruntime.EventsEmit(a.ctx, "cw:error", err.Error())
+			}
+		}
+		// Capture ended (stopped or errored) — clear state so a restart works.
+		a.cwMu.Lock()
+		if a.cwStop == stop {
+			a.cwStop = nil
+		}
+		a.cwMu.Unlock()
+	}()
+	return nil
+}
+
+// StopCWDecoder halts the CW decoder if running.
+func (a *App) StopCWDecoder() {
+	a.cwMu.Lock()
+	stop := a.cwStop
+	a.cwStop = nil
+	a.cwMu.Unlock()
+	if stop != nil {
+		close(stop)
+	}
+}
+
+// CWDecoderRunning reports whether the decoder is currently capturing.
+func (a *App) CWDecoderRunning() bool {
+	a.cwMu.Lock()
+	defer a.cwMu.Unlock()
+	return a.cwStop != nil
+}

frontend/src/App.tsx

@@ -1,6 +1,6 @@
 import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
 import {
-  AlertCircle, Antenna, CheckCircle2, Clock, Compass, Database, Eraser, Hash, Loader2, Lock,
+  AlertCircle, Antenna, CheckCircle2, Clock, Compass, Database, Ear, Eraser, Hash, Loader2, Lock,
   Maximize2, Minimize2, Mic, Pencil, RadioTower, RefreshCw, Satellite, Send, Settings, SlidersHorizontal, Square, Trash2, Unlock, X, Zap,
 } from 'lucide-react';
 
@@ -29,6 +29,7 @@ import {
   GetWinkeyerSettings, SaveWinkeyerSettings, ListSerialPorts, GetWinkeyerStatus,
   WinkeyerConnect, WinkeyerDisconnect, WinkeyerSend, WinkeyerStop, WinkeyerSetSpeed, WinkeyerBackspace,
   GetDVKMessages, GetDVKStatus, DVKPlay, DVKStop,
+  StartCWDecoder, StopCWDecoder,
   QSOAudioBegin, QSOAudioCancel, QSOAudioRestart,
   GetAwardDefs,
   GetUIPref,
@@ -590,6 +591,27 @@ export default function App() {
   useEffect(() => { wkEscClearsRef.current = wkEscClears; }, [wkEscClears]);
 
   // === Digital Voice Keyer (DVK) ===
+  // CW decoder: taps RX audio and decodes Morse. Runs only when enabled AND the
+  // mode is CW. The decoded text appears in a strip above the tabs.
+  const [cwEnabled, setCwEnabled] = useState(() => localStorage.getItem('opslog.cwDecoder') === '1');
+  const [cwText, setCwText] = useState('');
+  const [cwStatus, setCwStatus] = useState<{ wpm: number; pitch: number; level: number; active: boolean }>({ wpm: 0, pitch: 0, level: 0, active: false });
+  const cwOn = cwEnabled && mode === 'CW';
+  useEffect(() => {
+    const offT = EventsOn('cw:text', (t: string) => setCwText((s) => (s + t).slice(-2000)));
+    const offS = EventsOn('cw:status', (st: any) => setCwStatus(st));
+    const offE = EventsOn('cw:error', (e: string) => { setError(String(e)); setCwEnabled(false); });
+    return () => { offT?.(); offS?.(); offE?.(); };
+  }, []);
+  // Start/stop the backend decoder as the (enabled, mode) combination changes.
+  useEffect(() => {
+    if (cwOn) { StartCWDecoder().catch((e: any) => { setError(String(e?.message ?? e)); setCwEnabled(false); }); }
+    else { StopCWDecoder().catch(() => {}); }
+  }, [cwOn]);
+  function toggleCwDecoder() {
+    setCwEnabled((v) => { const n = !v; localStorage.setItem('opslog.cwDecoder', n ? '1' : '0'); return n; });
+  }
+
   const [dvkEnabled, setDvkEnabled] = useState(false);
   const [dvkMsgs, setDvkMsgs] = useState<DVKMsg[]>([]);
   const [dvkStat, setDvkStat] = useState<DVKStat>({ recording: false, playing: false, rec_slot: 0 });
@@ -1943,6 +1965,7 @@ export default function App() {
       { type: 'separator' },
       { type: 'item', label: wkEnabled ? '✓ WinKeyer CW keyer' : 'WinKeyer CW keyer', action: 'tools.winkeyer' },
       { type: 'item', label: dvkEnabled ? '✓ Digital Voice Keyer' : 'Digital Voice Keyer', action: 'tools.dvk' },
+      { type: 'item', label: cwEnabled ? '✓ CW decoder (RX audio)' : 'CW decoder (RX audio)', action: 'tools.cwdecoder' },
       { type: 'separator' },
       // Maintenance — bumped here while we only have one entry. Will move
       // to a Tools → Maintenance submenu once Clublog + LoTW refresh land.
@@ -1952,7 +1975,7 @@ export default function App() {
     { name: 'help', label: 'Help', items: [
       { type: 'item', label: 'About OpsLog', action: 'help.about' },
     ]},
-  ], [total, selectedId, selectedIds, ctyRefreshing, refsDownloading, exporting, wkEnabled, dvkEnabled]);
+  ], [total, selectedId, selectedIds, ctyRefreshing, refsDownloading, exporting, wkEnabled, dvkEnabled, cwEnabled]);
 
   function handleMenu(action: string) {
     switch (action) {
@@ -1969,6 +1992,7 @@ export default function App() {
       case 'tools.qsldesigner': setQslDesignerOpen(true); break;
       case 'tools.winkeyer':    wkSetEnabled(!wkEnabled); break;
       case 'tools.dvk':         setDvkEnabled((v) => !v); break;
+      case 'tools.cwdecoder':   toggleCwDecoder(); break;
       case 'tools.refreshCty':  refreshCtyDat(); break;
       case 'tools.downloadRefs': downloadRefs(); break;
       case 'help.about':        setShowAbout(true); break;
@@ -2776,6 +2800,24 @@ export default function App() {
               <Zap className="size-4" />
               {wkStatus.busy && <span className="absolute -top-0.5 -right-0.5 size-2 rounded-full bg-amber-500 animate-pulse" />}
             </button>
+            <button
+              type="button"
+              onClick={toggleCwDecoder}
+              title={
+                cwEnabled
+                  ? (mode === 'CW' ? 'CW decoder — on (decoding) · click to disable' : 'CW decoder — on, idle until CW mode · click to disable')
+                  : 'CW decoder · click to enable (decodes RX audio in CW mode)'
+              }
+              className={cn(
+                'relative inline-flex items-center justify-center size-7 rounded-md border transition-colors',
+                cwOn && cwStatus.active ? 'border-emerald-400 bg-emerald-100 text-emerald-800'
+                  : cwEnabled ? 'border-emerald-300 bg-emerald-50 text-emerald-700 hover:bg-emerald-100'
+                  : 'border-border text-muted-foreground hover:bg-muted',
+              )}
+            >
+              <Ear className="size-4" />
+              {cwOn && cwStatus.active && <span className="absolute -top-0.5 -right-0.5 size-2 rounded-full bg-emerald-500 animate-pulse" />}
+            </button>
             <button
               type="button"
               onClick={() => { const v = !showRotor; setShowRotor(v); writeUiPref('opslog.showRotor', v ? '1' : '0'); }}
@@ -3148,6 +3190,41 @@ export default function App() {
       )}
       </div>{/* /entry + aside row */}
 
+      {/* ===== CW decoder strip (only when enabled AND mode is CW) ===== */}
+      {cwOn && (
+        <div className="mx-2.5 mb-1 flex items-center gap-2 rounded-md border border-emerald-300/70 bg-emerald-50/60 px-2 py-1 text-xs">
+          <Ear className={cn('size-4 shrink-0', cwStatus.active ? 'text-emerald-600' : 'text-muted-foreground')} />
+          {/* Input-level meter — if this stays flat with a strong signal, the RX
+              audio device is wrong/silent rather than a decode problem. */}
+          <div className="shrink-0 w-12 h-1.5 rounded bg-muted overflow-hidden" title={`Audio level ${Math.round(cwStatus.level * 100)}%`}>
+            <div className="h-full bg-emerald-500 transition-[width] duration-100" style={{ width: `${Math.min(100, Math.round(cwStatus.level * 100))}%` }} />
+          </div>
+          <span className="shrink-0 font-mono text-[10px] text-muted-foreground tabular-nums">
+            {cwStatus.wpm > 0 ? `${cwStatus.wpm} WPM` : '— WPM'} · {cwStatus.pitch > 0 ? `${cwStatus.pitch} Hz` : '— Hz'}
+          </span>
+          <div className="flex-1 min-w-0 overflow-x-auto whitespace-nowrap font-mono leading-5">
+            {cwText.trim() === '' ? (
+              <span className="text-muted-foreground italic">listening…</span>
+            ) : (
+              cwText.trim().split(/\s+/).map((tok, i) => (
+                <button
+                  key={i}
+                  type="button"
+                  className="mr-1 rounded px-1 hover:bg-emerald-200/70"
+                  title="Use as callsign"
+                  onClick={() => onCallsignInput(tok, { force: true })}
+                >
+                  {tok}
+                </button>
+              ))
+            )}
+          </div>
+          <button type="button" className="shrink-0 text-muted-foreground hover:text-foreground" title="Clear" onClick={() => setCwText('')}>
+            <Eraser className="size-3.5" />
+          </button>
+        </div>
+      )}
+
       {/* ===== LOWER: tabbed table / cluster / band map ===== */}
       {compact ? null : <>
       <div className={cn('grid gap-2.5 p-2.5 flex-1 min-h-0 grid-rows-[minmax(0,1fr)]',

frontend/wailsjs/go/main/App.d.ts

@@ -41,6 +41,8 @@ export function BulkUpdateField(arg1:Array<number>,arg2:string,arg3:string):Prom
 
 export function BulkUpdateQSL(arg1:Array<number>,arg2:main.QSLBulkUpdate):Promise<number>;
 
+export function CWDecoderRunning():Promise<boolean>;
+
 export function CheckForUpdate():Promise<main.UpdateInfo>;
 
 export function ClearLookupCache():Promise<void>;
@@ -469,6 +471,10 @@ export function SetUIPref(arg1:string,arg2:string):Promise<void>;
 
 export function SetUltrabeamDirection(arg1:number):Promise<void>;
 
+export function StartCWDecoder():Promise<void>;
+
+export function StopCWDecoder():Promise<void>;
+
 export function SwitchCATRig(arg1:number):Promise<void>;
 
 export function SyncPOTAHunterLog(arg1:boolean,arg2:boolean):Promise<main.POTASyncResult>;

frontend/wailsjs/go/main/App.js

@@ -54,6 +54,10 @@ export function BulkUpdateQSL(arg1, arg2) {
   return window['go']['main']['App']['BulkUpdateQSL'](arg1, arg2);
 }
 
+export function CWDecoderRunning() {
+  return window['go']['main']['App']['CWDecoderRunning']();
+}
+
 export function CheckForUpdate() {
   return window['go']['main']['App']['CheckForUpdate']();
 }
@@ -910,6 +914,14 @@ export function SetUltrabeamDirection(arg1) {
   return window['go']['main']['App']['SetUltrabeamDirection'](arg1);
 }
 
+export function StartCWDecoder() {
+  return window['go']['main']['App']['StartCWDecoder']();
+}
+
+export function StopCWDecoder() {
+  return window['go']['main']['App']['StopCWDecoder']();
+}
+
 export function SwitchCATRig(arg1) {
   return window['go']['main']['App']['SwitchCATRig'](arg1);
 }

internal/audio/cwtap.go

@@ -0,0 +1,17 @@
+package audio
+
+// SampleRate is the fixed capture rate (mono 16-bit PCM). Exported so consumers
+// like the CW decoder can configure their DSP to match.
+const SampleRate = sampleRate
+
+// StreamCapture captures from deviceID and calls onSamples with mono 16-bit PCM
+// frames (as int16) until stop closes. A thin wrapper over the internal capture
+// loop for live consumers (the CW decoder) that want samples, not raw bytes.
+func StreamCapture(deviceID string, stop <-chan struct{}, onSamples func([]int16)) error {
+	return captureStream(deviceID, stop, func(chunk []byte) {
+		if len(chunk) == 0 {
+			return
+		}
+		onSamples(bytesToInt16(chunk))
+	})
+}

internal/cwdecode/cwdecode.go

@@ -0,0 +1,275 @@
+// Package cwdecode is a real-time CW (Morse) decoder: it turns a stream of
+// mono PCM samples into decoded text. The pipeline is the classic one — a bank
+// of Goertzel tone detectors (auto-picking the dominant pitch), an adaptive
+// envelope/threshold to recover key-down/key-up, an adaptive dot-length (WPM)
+// estimate, and a timing state machine that maps marks/spaces to Morse and
+// then to characters.
+//
+// It is deliberately self-contained and dependency-free so it can be unit
+// tested with synthetic signals. Robustness on weak/QRM/QSB signals is limited
+// (as with every audio CW decoder); it does well on clean signals.
+package cwdecode
+
+import "math"
+
+// Status is a periodic snapshot for the UI (pitch lock, speed, signal).
+type Status struct {
+	WPM    int     `json:"wpm"`
+	Pitch  int     `json:"pitch"`  // Hz of the locked tone
+	Level  float64 `json:"level"`  // 0..1 rough signal strength (SNR proxy)
+	Active bool    `json:"active"` // a tone is currently keyed down
+}
+
+// Decoder consumes PCM and emits decoded characters via onChar (one or more
+// characters at a time, including " " for word gaps) and periodic onStatus.
+type Decoder struct {
+	fs      int
+	hop     int // samples between envelope updates
+	win     int // Goertzel window length
+	freqs   []float64
+	coeffs  []float64 // precomputed 2*cos(w) per freq
+
+	ring []float64 // last win samples
+	acc  int       // samples since last hop
+
+	// Adaptive envelope (relative, so absolute gain is irrelevant).
+	peak, floor float64
+	state       bool // true = mark (key down)
+	stateHops   int
+	dotHops     float64 // adaptive dot length, in hops
+
+	elem         []byte // current "." / "-" run for the in-progress character
+	charEmitted  bool   // current space already flushed a character
+	wordEmitted  bool   // current space already flushed a word gap
+	lastPitch    float64
+	lastRMS      float64 // 0..1 input level of the current window (for the UI meter)
+
+	statusEvery int
+	sinceStatus int
+
+	onChar   func(string)
+	onStatus func(Status)
+}
+
+var morse = map[string]byte{
+	".-": 'A', "-...": 'B', "-.-.": 'C', "-..": 'D', ".": 'E', "..-.": 'F',
+	"--.": 'G', "....": 'H', "..": 'I', ".---": 'J', "-.-": 'K', ".-..": 'L',
+	"--": 'M', "-.": 'N', "---": 'O', ".--.": 'P', "--.-": 'Q', ".-.": 'R',
+	"...": 'S', "-": 'T', "..-": 'U', "...-": 'V', ".--": 'W', "-..-": 'X',
+	"-.--": 'Y', "--..": 'Z',
+	"-----": '0', ".----": '1', "..---": '2', "...--": '3', "....-": '4',
+	".....": '5', "-....": '6', "--...": '7', "---..": '8', "----.": '9',
+	".-.-.-": '.', "--..--": ',', "..--..": '?', "-..-.": '/', "-...-": '=',
+	".-.-.": '+', "-.-.--": '!', "---...": ':', "-....-": '-', ".--.-.": '@',
+}
+
+// New builds a decoder for the given sample rate. onChar receives decoded text
+// incrementally; onStatus receives ~10 snapshots/second. Either may be nil.
+func New(sampleRate int, onChar func(string), onStatus func(Status)) *Decoder {
+	if sampleRate <= 0 {
+		sampleRate = 16000
+	}
+	d := &Decoder{
+		fs:          sampleRate,
+		hop:         sampleRate / 250,  // ~4 ms envelope resolution
+		win:         sampleRate / 62,   // ~16 ms Goertzel window
+		dotHops:     15,                // ~20 WPM seed (15 hops * 4 ms = 60 ms)
+		statusEvery: 25,                // ~10 Hz status
+		onChar:      onChar,
+		onStatus:    onStatus,
+	}
+	if d.hop < 1 {
+		d.hop = 1
+	}
+	// Candidate CW tones: 250–1200 Hz every 25 Hz (wide enough for most rigs'
+	// audio offset). The dominant bin is the pitch (auto), and its magnitude
+	// drives the envelope.
+	for f := 250.0; f <= 1200.0; f += 25 {
+		d.freqs = append(d.freqs, f)
+		d.coeffs = append(d.coeffs, 2*math.Cos(2*math.Pi*f/float64(d.fs)))
+	}
+	return d
+}
+
+// Reset clears decode state (e.g. when the user re-arms the decoder).
+func (d *Decoder) Reset() {
+	d.ring = d.ring[:0]
+	d.acc = 0
+	d.peak, d.floor = 0, 0
+	d.state = false
+	d.stateHops = 0
+	d.dotHops = 15
+	d.elem = d.elem[:0]
+	d.charEmitted, d.wordEmitted = false, false
+}
+
+// Process feeds a block of mono samples through the decoder.
+func (d *Decoder) Process(samples []int16) {
+	for _, s := range samples {
+		d.ring = append(d.ring, float64(s))
+		if len(d.ring) > d.win {
+			d.ring = d.ring[len(d.ring)-d.win:]
+		}
+		d.acc++
+		if d.acc >= d.hop && len(d.ring) >= d.win {
+			d.acc = 0
+			mag, pitch := d.toneMag()
+			d.step(mag, pitch)
+		}
+	}
+}
+
+// toneMag runs the Goertzel bank over the current window and returns the
+// strongest bin's magnitude and its frequency (the auto-detected pitch).
+func (d *Decoder) toneMag() (float64, float64) {
+	best, bestF := 0.0, d.lastPitch
+	n := float64(len(d.ring))
+	var sumSq float64
+	for i, coeff := range d.coeffs {
+		var s1, s2 float64
+		for _, x := range d.ring {
+			s0 := x + coeff*s1 - s2
+			s2 = s1
+			s1 = s0
+		}
+		power := s1*s1 + s2*s2 - coeff*s1*s2
+		if power > best {
+			best = power
+			bestF = d.freqs[i]
+		}
+	}
+	for _, x := range d.ring {
+		sumSq += x * x
+	}
+	d.lastRMS = math.Min(1, math.Sqrt(sumSq/n)/32768*4) // ×4 so quiet audio is visible
+	// Normalise by window length so the magnitude scale is rate-independent.
+	return math.Sqrt(math.Max(best, 0)) / n, bestF
+}
+
+// step advances the envelope follower + timing state machine by one hop.
+func (d *Decoder) step(mag, pitch float64) {
+	// Envelope: fast attack / slow release for the peak, fast drop / slow rise
+	// for the noise floor. Tracks the signal even through QSB.
+	if mag > d.peak {
+		d.peak += (mag - d.peak) * 0.4
+	} else {
+		d.peak += (mag - d.peak) * 0.02
+	}
+	if mag < d.floor {
+		d.floor += (mag - d.floor) * 0.4
+	} else {
+		d.floor += (mag - d.floor) * 0.01
+	}
+
+	span := d.peak - d.floor
+	// Hysteresis thresholds; require a minimum SNR span to call anything a tone.
+	on := d.state
+	if span > d.floor*0.3+1e-9 {
+		onTh := d.floor + 0.55*span
+		offTh := d.floor + 0.35*span
+		if d.state {
+			on = mag > offTh
+		} else {
+			on = mag > onTh
+		}
+		if on {
+			d.lastPitch = pitch
+		}
+	} else {
+		on = false
+	}
+
+	if on == d.state {
+		d.stateHops++
+		if !d.state {
+			d.spaceProgress() // flush char/word as the gap grows
+		}
+	} else {
+		if d.state {
+			d.endMark(d.stateHops)
+		}
+		d.state = on
+		d.stateHops = 1
+		if on {
+			// A new mark starts → the previous space is over; re-arm flushing.
+			d.charEmitted, d.wordEmitted = false, false
+		}
+	}
+
+	d.emitStatus(on)
+}
+
+// endMark classifies a finished key-down run as a dot or dash and adapts the
+// dot-length estimate.
+func (d *Decoder) endMark(hops int) {
+	h := float64(hops)
+	// Reject impulse noise far shorter than a dot.
+	if h < d.dotHops*0.35 {
+		return
+	}
+	dash := h > d.dotHops*2
+	if dash {
+		d.elem = append(d.elem, '-')
+		d.adaptDot(h / 3)
+	} else {
+		d.elem = append(d.elem, '.')
+		d.adaptDot(h)
+	}
+}
+
+// adaptDot nudges the dot-length estimate toward an observation (EMA, clamped
+// to ~5–100 WPM).
+func (d *Decoder) adaptDot(obs float64) {
+	d.dotHops = d.dotHops*0.7 + obs*0.3
+	if d.dotHops < 3 {
+		d.dotHops = 3
+	}
+	if d.dotHops > 60 {
+		d.dotHops = 60
+	}
+}
+
+// spaceProgress flushes the current character once the gap exceeds a character
+// gap, and a word space once it exceeds a word gap.
+func (d *Decoder) spaceProgress() {
+	g := float64(d.stateHops)
+	if !d.charEmitted && g > d.dotHops*2 {
+		d.flushChar()
+		d.charEmitted = true
+	}
+	if !d.wordEmitted && g > d.dotHops*5 {
+		if d.onChar != nil {
+			d.onChar(" ")
+		}
+		d.wordEmitted = true
+	}
+}
+
+// flushChar looks up the accumulated element string and emits the character.
+func (d *Decoder) flushChar() {
+	if len(d.elem) == 0 {
+		return
+	}
+	if c, ok := morse[string(d.elem)]; ok {
+		if d.onChar != nil {
+			d.onChar(string(c))
+		}
+	} else if d.onChar != nil {
+		d.onChar("?")
+	}
+	d.elem = d.elem[:0]
+}
+
+func (d *Decoder) emitStatus(on bool) {
+	d.sinceStatus++
+	if d.sinceStatus < d.statusEvery || d.onStatus == nil {
+		return
+	}
+	d.sinceStatus = 0
+	hopMs := float64(d.hop) / float64(d.fs) * 1000
+	wpm := 0
+	if d.dotHops > 0 {
+		wpm = int(math.Round(1200 / (d.dotHops * hopMs)))
+	}
+	d.onStatus(Status{WPM: wpm, Pitch: int(math.Round(d.lastPitch)), Level: d.lastRMS, Active: on})
+}

internal/cwdecode/cwdecode_test.go

@@ -0,0 +1,98 @@
+package cwdecode
+
+import (
+	"math"
+	"strings"
+	"testing"
+)
+
+// reverse Morse map for the synthesizer.
+func charToMorse() map[byte]string {
+	m := map[byte]string{}
+	for code, ch := range morse {
+		m[ch] = code
+	}
+	return m
+}
+
+// keyMessage synthesizes a clean keyed tone for msg at the given WPM/pitch.
+func keyMessage(msg string, fs, wpm int, pitch float64) []int16 {
+	dot := fs * 1200 / (wpm * 1000) // samples per dot
+	c2m := charToMorse()
+	var out []int16
+	phase := 0.0
+	dphi := 2 * math.Pi * pitch / float64(fs)
+
+	tone := func(n int) {
+		for i := 0; i < n; i++ {
+			out = append(out, int16(9000*math.Sin(phase)))
+			phase += dphi
+		}
+	}
+	silence := func(n int) {
+		for i := 0; i < n; i++ {
+			out = append(out, 0)
+		}
+	}
+
+	silence(fs / 4) // 250 ms lead-in for AGC warmup
+	for i := 0; i < len(msg); i++ {
+		ch := msg[i]
+		if ch == ' ' {
+			silence(7 * dot)
+			continue
+		}
+		code := c2m[ch]
+		for j := 0; j < len(code); j++ {
+			if code[j] == '.' {
+				tone(dot)
+			} else {
+				tone(3 * dot)
+			}
+			silence(dot) // inter-element gap
+		}
+		silence(3 * dot) // inter-character gap (on top of the trailing element gap)
+	}
+	silence(fs / 4)
+	return out
+}
+
+func TestDecodeCleanSignal(t *testing.T) {
+	const fs = 16000
+	var sb strings.Builder
+	d := New(fs, func(s string) { sb.WriteString(s) }, nil)
+
+	// Repeat so AGC warm-up only costs the first word.
+	samples := keyMessage("PARIS PARIS PARIS", fs, 22, 700)
+	// Feed in small chunks like the live capture would.
+	for i := 0; i < len(samples); i += 256 {
+		end := i + 256
+		if end > len(samples) {
+			end = len(samples)
+		}
+		d.Process(samples[i:end])
+	}
+
+	got := strings.ToUpper(sb.String())
+	if !strings.Contains(got, "PARIS") {
+		t.Fatalf("decoded %q, want it to contain PARIS", got)
+	}
+}
+
+func TestDecodeNumbersAndProsign(t *testing.T) {
+	const fs = 16000
+	var sb strings.Builder
+	d := New(fs, func(s string) { sb.WriteString(s) }, nil)
+	samples := keyMessage("TEST 599 TEST", fs, 18, 650)
+	for i := 0; i < len(samples); i += 200 {
+		end := i + 200
+		if end > len(samples) {
+			end = len(samples)
+		}
+		d.Process(samples[i:end])
+	}
+	got := strings.ToUpper(sb.String())
+	if !strings.Contains(got, "599") {
+		t.Fatalf("decoded %q, want it to contain 599", got)
+	}
+}