o debugger

- DISPLAY command only opens the display if it is called without
	additional arguments.
    - for example, calling "DISPLAY DEBUGCOLORS" does not cause the
	display to appear.

debugger/commands.go

@@ -761,13 +761,15 @@ func (dbg *Debugger) parseCommand(userInput string) (bool, error) {
 	case KeywordDisplay:
 		var err error
 
-		visibility := true
 		action, present := tokens.Get()
 		if present {
 			action = strings.ToUpper(action)
 			switch action {
 			case "OFF":
-				visibility = false
+				err = dbg.vcs.TV.SetFeature(television.ReqSetVisibility, false)
+				if err != nil {
+					return false, err
+				}
 			case "DEBUG":
 				err = dbg.vcs.TV.SetFeature(television.ReqToggleDebug)
 				if err != nil {
@@ -796,11 +798,11 @@ func (dbg *Debugger) parseCommand(userInput string) (bool, error) {
 			default:
 				return false, fmt.Errorf("unknown display action (%s)", action)
 			}
-		}
-
-		err = dbg.vcs.TV.SetFeature(television.ReqSetVisibility, visibility)
-		if err != nil {
-			return false, err
+		} else {
+			err = dbg.vcs.TV.SetFeature(television.ReqSetVisibility, true)
+			if err != nil {
+				return false, err
+			}
 		}
 
 	case KeywordMouse:

hardware/tia/hmove.go

@@ -73,6 +73,11 @@ func (hm *hmove) isset() bool {
 	return hm.latch
 }
 
+// isjustset checks to see if the horiztonal movement sequence has just started
+func (hm *hmove) isjustset() bool {
+	return hm.count == 15 && hm.phase == hm.colorClock.Phase
+}
+
 // tick returns the current hmove ripple counter and whether a tick has occurred
 func (hm *hmove) tick() (int, bool) {
 	// if we've reached a count of -1 then no tick will ever occur

hardware/tia/rsync.go

@@ -27,7 +27,7 @@ func newRsync(colorClock *polycounter.Polycounter) *rsync {
 
 // MachineInfoTerse returns the RSYNC information in verbose format
 func (rs rsync) MachineInfoTerse() string {
-	if rs.isActive() {
+	if rs.isactive() {
 		return fmt.Sprintf("RS=%d", rs.remainingCycles)
 	}
 	return "RS=-"
@@ -35,7 +35,7 @@ func (rs rsync) MachineInfoTerse() string {
 
 // MachineInfo returns the RSYNC information in verbose format
 func (rs rsync) MachineInfo() string {
-	if rs.isActive() {
+	if rs.isactive() {
 		return fmt.Sprintf("rsync: reset in %d cycle(s)", rs.remainingCycles)
 	}
 	return "rsync: not set"
@@ -46,7 +46,7 @@ func (rs rsync) String() string {
 	return rs.MachineInfo()
 }
 
-func (rs rsync) isActive() bool {
+func (rs rsync) isactive() bool {
 	return rs.remainingCycles > -1
 }
 
@@ -62,6 +62,10 @@ func (rs *rsync) set() {
 	rs.colorClock.ResetPhase()
 }
 
+func (rs *rsync) isjustset() bool {
+	return rs.remainingCycles == 5
+}
+
 func (rs *rsync) tick() bool {
 	if rs.remainingCycles == -1 {
 		return false

hardware/tia/tia.go

@@ -182,6 +182,15 @@ func (tia *TIA) StepVideoCycle() bool {
 		tia.motionClock = false
 	}
 
+	// send metasignal information before we perform any state ticking
+	err := tia.tv.MetaSignal(television.MetaSignalAttributes{
+		Hmove: tia.Hmove.isjustset(),
+		Rsync: tia.rsync.isjustset(),
+		Wsync: tia.wsync})
+	if err != nil {
+		panic(err)
+	}
+
 	// set up new scanline if colorClock has ticked its way to the reset point or if
 	// an rsync has matured (see rsync.go commentary)
 	if tia.rsync.tick() {
@@ -224,7 +233,7 @@ func (tia *TIA) StepVideoCycle() bool {
 	}
 
 	// at the end of the video cycle we want to finally signal the televison
-	err := tia.tv.Signal(television.SignalAttributes{
+	err = tia.tv.Signal(television.SignalAttributes{
 		VSync:      tia.vsync,
 		VBlank:     tia.vblank,
 		FrontPorch: frontPorch,

hardware/tia/video/video.go

@@ -130,6 +130,7 @@ func (vd *Video) ResolveHorizMovement(count int) {
 // present. it also sets the collision registers
 // - it need not be called therefore during VBLANK or HBLANK
 func (vd *Video) Pixel(debugColors bool) uint8 {
+	bgc := vd.Playfield.backgroundColor
 	pfu, pfc := vd.Playfield.pixel()
 	blu, blc := vd.Ball.pixel()
 	p0u, p0c := vd.Player0.pixel()
@@ -138,9 +139,15 @@ func (vd *Video) Pixel(debugColors bool) uint8 {
 	m1u, m1c := vd.Missile1.pixel()
 
 	// override program colors with debug colors
+	// -- same/similar colors to those used in the Stella emulator
 	if debugColors {
+		bgc = 0x00 // black (stella uses a light grey)
+		blc = 0xb4 // cyan
+		pfc = 0x62 // purple
 		p0c = 0x32 // red
-		p1c = 0x15 // gold
+		p1c = 0x12 // gold
+		m0c = 0xf2 // orange
+		m1c = 0xd2 // green
 	}
 
 	// collisions
@@ -266,7 +273,7 @@ func (vd *Video) Pixel(debugColors bool) uint8 {
 	}
 
 	// priority 4
-	return vd.Playfield.backgroundColor
+	return bgc
 }
 
 func createTriggerList(playerSize uint8) []int {

television/headless.go

@@ -253,6 +253,11 @@ func (tv *HeadlessTV) Signal(sig SignalAttributes) error {
 	return tv.HookSetPixel(x, y, red, green, blue, sig.VBlank)
 }
 
+// MetaSignal recieves (and processes) additional emulator information from the emulator
+func (tv *HeadlessTV) MetaSignal(MetaSignalAttributes) error {
+	return nil
+}
+
 // GetState returns the TVState object for the named state. television
 // implementations in other packages will difficulty extending this function
 // because TVStateReq does not expose its members. (although it may need to if

television/sdltv/callback.go

@@ -1,6 +1,6 @@
 package sdltv
 
-// callback is used to wrap functions supplied to RequestCallbackRegistration()
+// callback is used to wrap functions supplied to RequestCallback()
 
 type callback struct {
 	channel  chan func()

television/sdltv/screen.go

@@ -24,8 +24,8 @@ type screen struct {
 	lastX int32
 	lastY int32
 
-	// pixels arrays are of maximum screen size - actual smalled screens are
-	// masked appropriately
+	// pixels arrays are of maximum screen size - actual smaller play screens
+	// are masked appropriately
 	pixels     []byte
 	pixelsFade []byte
 
@@ -54,6 +54,9 @@ type screen struct {
 
 	// stabiliser to make sure image remains solid
 	stb *screenStabiliser
+
+	// overlay for screen showing metasignal information
+	metasignals *metasignalOverlay
 }
 
 func newScreen(tv *SDLTV) (*screen, error) {
@@ -112,6 +115,12 @@ func newScreen(tv *SDLTV) (*screen, error) {
 	// new stabiliser
 	scr.stb = newScreenStabiliser(scr)
 
+	// new overlay
+	scr.metasignals, err = newMetasignalOverlay(scr)
+	if err != nil {
+		return nil, err
+	}
+
 	return scr, nil
 }
 
@@ -204,6 +213,12 @@ func (scr *screen) setPixel(x, y int32, red, green, blue byte, vblank bool) erro
 func (scr *screen) update(paused bool) error {
 	var err error
 
+	// update additional overlays
+	err = scr.metasignals.update()
+	if err != nil {
+		return err
+	}
+
 	// clear image from rendered. using a non-video-black color if screen is
 	// unmasked
 	if scr.unmasked {
@@ -242,6 +257,14 @@ func (scr *screen) update(paused bool) error {
 		return err
 	}
 
+	// show debugging overlay
+	if scr.unmasked {
+		err = scr.renderer.Copy(scr.metasignals.texture, scr.srcRect, scr.destRect)
+		if err != nil {
+			return err
+		}
+	}
+
 	// add cursor if tv is paused
 	// - drawing last so that cursor isn't masked
 	if paused {
@@ -291,7 +314,7 @@ func (scr *screen) update(paused bool) error {
 	return nil
 }
 
-func (scr *screen) swapPixels() {
+func (scr *screen) clearPixels() {
 	// swap which pixel buffer we're using in time for next round of pixel
 	// plotting
 	swp := scr.pixels
@@ -302,4 +325,7 @@ func (scr *screen) swapPixels() {
 	for i := 0; i < len(scr.pixels); i++ {
 		scr.pixels[i] = 0
 	}
+
+	// clear pixels in additional overlays
+	scr.metasignals.clearPixels()
 }

television/sdltv/sdltv.go

@@ -77,9 +77,9 @@ func NewSDLTV(tvType string, scale float32) (*SDLTV, error) {
 	}
 
 	// register headlesstv callbacks
-	// leave SignalNewScanline() hook at its default
+	// --leave SignalNewScanline() hook at its default
 	tv.HookNewFrame = func() error {
-		defer tv.scr.swapPixels()
+		defer tv.scr.clearPixels()
 		err := tv.scr.stb.checkStableFrame()
 		if err != nil {
 			return err

television/television.go

@@ -49,6 +49,15 @@ type SignalAttributes struct {
 	Pixel                                    ColorSignal
 }
 
+// MetaSignalAttributes represents any additional emulator data sent to the
+// "television" (in inverted commas). not all television implementations need
+// to do anything useful with this information.
+type MetaSignalAttributes struct {
+	Hmove bool
+	Rsync bool
+	Wsync bool
+}
+
 // Television defines the operations that can be performed on the television
 type Television interface {
 	MachineInfoTerse() string
@@ -56,6 +65,7 @@ type Television interface {
 
 	Reset() error
 	Signal(SignalAttributes) error
+	MetaSignal(MetaSignalAttributes) error
 
 	GetState(StateReq) (interface{}, error)
 	GetMetaState(MetaStateReq) (string, error)