feat(udp): spot clicks switch the decoder's mode

Configure (message 15), mode field only, every other field sent as no-change: an FT4 spot clicked while WSJT-X sits in FT8 lands the operator ready to decode instead of staring at gibberish. Sent to every instance heard this session — one already in the right mode treats it as a no-op — and only for modes the decoder actually speaks (FT8/FT4/JT65/JT9/MSK144/ Q65/FST4); CW and SSB are none of its business. Toggle in the Connections panel, on by default.
2026-08-30 15:33:07 +02:00
parent daabbc63c7
commit 9bd6d988aa
8 changed files with 127 additions and 8 deletions
@@ -0,0 +1,47 @@
+package udp
+
+import (
+	"bytes"
+	"encoding/binary"
+
+	"hamlog/internal/applog"
+)
+
+// WSJT-X Configure (message 15) — change the decoder's settings remotely. Used
+// for ONE thing here: clicking an FT4 spot while the decoder sits in FT8
+// switches its mode too, so the operator lands ready to decode instead of
+// staring at a band of gibberish. Every other field is sent as "no change"
+// (empty strings, max-quint32), per the protocol.
+const wsjtMsgConfigure = 15
+
+// EncodeConfigureMode builds a Configure datagram that changes only the mode.
+func EncodeConfigureMode(programID, mode string) []byte {
+	const noChange32 = ^uint32(0)
+	var b bytes.Buffer
+	_ = binary.Write(&b, binary.BigEndian, uint32(wsjtMagic))
+	_ = binary.Write(&b, binary.BigEndian, uint32(2))
+	_ = binary.Write(&b, binary.BigEndian, uint32(wsjtMsgConfigure))
+	writeQString(&b, programID)
+	writeQString(&b, mode)                             // Mode
+	_ = binary.Write(&b, binary.BigEndian, noChange32) // Frequency Tolerance — no change
+	writeQString(&b, "")                               // Submode — no change
+	_ = binary.Write(&b, binary.BigEndian, uint8(0))   // Fast Mode — off (right for every HF mode)
+	_ = binary.Write(&b, binary.BigEndian, noChange32) // T/R Period — no change
+	_ = binary.Write(&b, binary.BigEndian, noChange32) // Rx DF — no change
+	writeQString(&b, "")                               // DX Call — no change
+	writeQString(&b, "")                               // DX Grid — no change
+	_ = binary.Write(&b, binary.BigEndian, uint8(0))   // Generate Messages — no
+	return b.Bytes()
+}
+
+// SendConfigureMode asks every decoder heard this session to switch mode.
+// Sent to all instances rather than one: the spot click does not say which
+// decoder the operator is looking at, and a second instance already in the
+// right mode treats the message as a no-op.
+func (m *Manager) SendConfigureMode(mode string) {
+	for _, inst := range m.Instances() {
+		if err := m.sendToInstance(inst, EncodeConfigureMode(inst, mode), "configure-mode"); err == nil {
+			applog.Printf("udp: asked %q to switch to %s", inst, mode)
+		}
+	}
+}