Fix iso write

README.md

@@ -35,8 +35,11 @@ To use the MSR605, make sure your user has access to the serial ports
 (`dialout` group for Debian-based, `uucp` for Arch).
 
 ## Limitations
-
-- Writing currently has some issues. I'll fix it soon!
+- Write seems to be working only in Hi-Co. Lo-Co still has some issues
 - The GUI looks different depending on your system theme; see [andlabs/ui](https://github.com/andlabs/ui)
 - Refreshing the list of devices just adds onto it.
 - Saving / opening files currently doesn't work, as I want to make it compatible with Deftun's MSRX software.
+
+## Disclaimer
+
+This fork's bug fixes and improvements were developed with the assistance of AI (Claude Code Max by Anthropic).

internal/gui/app.go

@@ -37,6 +37,7 @@ type App struct {
 	infoTypeCB     *ui.Combobox
 	showInfoButton *ui.Button
 	tracks         [3]*Track
+	lastRawTracks  [3][]byte
 	resetButton,
 	readButton,
 	writeButton,
@@ -59,7 +60,10 @@ func (a *App) throwErr(err error) {
 	if err == usb.ErrDeviceClosed {
 
 	} else {
-		ui.MsgBoxError(a.win, "Error", err.Error())
+		msg := err.Error()
+		ui.QueueMain(func() {
+			ui.MsgBoxError(a.win, "Error", msg)
+		})
 	}
 }
 
@@ -113,7 +117,8 @@ func (a *App) selectDevice(cb *ui.Combobox) {
 	if cb.Selected() == 0 {
 		return // already disconnected
 	}
-	d, err := a.availableDevs[cb.Selected()-1].Open()
+	devInfo := a.availableDevs[cb.Selected()-1]
+	d, err := devInfo.Open()
 	if err != nil {
 		cb.SetSelected(0)
 		a.throwErr(err)
@@ -160,13 +165,17 @@ func (a *App) setFrozen(f bool) {
 
 func (a *App) freeze() {
 	a.mu.Lock()
-	a.progBar.Show()
-	a.setFrozen(true)
+	ui.QueueMain(func() {
+		a.progBar.Show()
+		a.setFrozen(true)
+	})
 }
 
 func (a *App) unfreeze() {
-	a.setFrozen(false)
-	a.progBar.Hide()
+	ui.QueueMain(func() {
+		a.setFrozen(false)
+		a.progBar.Hide()
+	})
 	a.mu.Unlock()
 }
 
@@ -218,21 +227,47 @@ func (a *App) read() {
 		a.throwErr(err)
 		return
 	}
-	for i, t := range a.tracks {
-		chars, _, _ := t.decode(rawTracks[i])
-		t.edit.SetText(string(chars))
+	a.lastRawTracks = rawTracks
+	ui.QueueMain(func() {
+		for i, t := range a.tracks {
+			chars, _, _ := t.decode(rawTracks[i])
+			t.edit.SetText(string(chars))
+		}
+	})
+}
+
+// stripSentinels removes start sentinel (%/;/+) and end sentinel (?) from ISO track data.
+// DecodeRaw includes sentinels, but the MSR605 ISO write adds them automatically.
+func stripSentinels(data []byte) []byte {
+	if len(data) == 0 {
+		return data
+	}
+	start := 0
+	if data[0] == '%' || data[0] == ';' || data[0] == '+' {
+		start = 1
+	}
+	end := len(data)
+	if end > start && data[end-1] == '?' {
+		end--
 	}
+	return data[start:end]
 }
 
 func (a *App) write() {
 	a.freeze()
 	defer a.unfreeze()
+	// Coercivity is set by the radio button handler.
 	var tracks [3][]byte
-	for i, track := range a.tracks {
-		if !track.disabled {
-			tracks[i] = []byte(track.edit.Text())
+	done := make(chan struct{})
+	ui.QueueMain(func() {
+		for i, track := range a.tracks {
+			if !track.disabled {
+				tracks[i] = stripSentinels([]byte(track.edit.Text()))
+			}
 		}
-	}
+		close(done)
+	})
+	<-done
 	err := a.device.WriteISOTracks(tracks[0], tracks[1], tracks[2])
 	if err != nil {
 		a.throwErr(err)
@@ -242,15 +277,14 @@ func (a *App) write() {
 func (a *App) writeRaw() {
 	a.freeze()
 	defer a.unfreeze()
-	var rawTracks [3][]byte
-	for i, track := range a.tracks {
-		track.edit.SetReadOnly(true)
-		if !track.disabled {
-			chars := []byte(track.edit.Text())
-			rawTracks[i] = track.encode(chars)
-		}
+	// Coercivity is already set by the radio button handler (setCoercivity).
+	// Sending it again right before raw write causes immediate rejection on MSR605X.
+	// Restore standard leading zeros (may have been changed by previous operations).
+	if err := a.device.SetLeadingZeros(61, 22); err != nil {
+		a.throwErr(err)
+		return
 	}
-	err := a.device.WriteRawTracks(rawTracks[0], rawTracks[1], rawTracks[2])
+	err := a.device.WriteRawTracks(a.lastRawTracks[0], a.lastRawTracks[1], a.lastRawTracks[2])
 	if err != nil {
 		a.throwErr(err)
 	}
@@ -259,13 +293,29 @@ func (a *App) writeRaw() {
 func (a *App) erase() {
 	a.freeze()
 	defer a.unfreeze()
-	var tracks [3]bool
-	for i, t := range a.tracks {
-		if !t.disabled {
-			tracks[i] = true
-			t.edit.SetText("")
+	if a.coRadio.Selected() == hiCo {
+		if err := a.device.SetHiCo(); err != nil {
+			a.throwErr(err)
+			return
+		}
+	} else {
+		if err := a.device.SetLoCo(); err != nil {
+			a.throwErr(err)
+			return
 		}
 	}
+	var tracks [3]bool
+	done := make(chan struct{})
+	ui.QueueMain(func() {
+		for i, t := range a.tracks {
+			if !t.disabled {
+				tracks[i] = true
+				t.edit.SetText("")
+			}
+		}
+		close(done)
+	})
+	<-done
 	err := a.device.Erase(tracks[0], tracks[1], tracks[2])
 	if err != nil {
 		a.throwErr(err)
@@ -388,7 +438,9 @@ func MakeMainUI(win *ui.Window) ui.Control {
 	a.readButton = ui.NewButton("Read")
 	a.readButton.OnClicked(func(*ui.Button) { go a.read() })
 	a.writeButton = ui.NewButton("Write")
-	a.writeButton.OnClicked(func(*ui.Button) { go a.write() })
+	a.writeButton.OnClicked(func(*ui.Button) {
+		go a.write()
+	})
 	a.eraseButton = ui.NewButton("Erase")
 	a.eraseButton.OnClicked(func(*ui.Button) { go a.erase() })
 	a.openButton = ui.NewButton("Open file")
@@ -420,7 +472,6 @@ func MakeMainUI(win *ui.Window) ui.Control {
 	if len(a.availableDevs) > 0 {
 		d, err := a.availableDevs[0].Open()
 		if err == nil {
-			a.device = libmsr.NewDevice(d)
 			a.deviceCB.SetSelected(1)
 			a.connect(d)
 		}