Further reduce the number of things that know about HostInterface

devices/serial_port.go

@@ -73,19 +73,23 @@ func (sc *SerialCtrl) SetClockInternal(enabled bool) {
 }
 
 type SerialPort struct {
-	clk  uint
-	ctrl SerialCtrl
-	recv byte
-	buf  byte
-	host HostInterface
+	clk   uint
+	ctrl  SerialCtrl
+	recv  byte
+	buf   byte
+	cable SerialCable
 }
 
-func NewSerialPort(host HostInterface) *SerialPort {
+func NewSerialPort() *SerialPort {
 	return &SerialPort{
-		host: host,
+		cable: &NullSerialCable{},
 	}
 }
 
+func (sp *SerialPort) AttachCable(cable SerialCable) {
+	sp.cable = cable
+}
+
 func (sp *SerialPort) Step(cycles uint8, ic *InterruptController) {
 	if !sp.ctrl.IsTransferEnabled() {
 		return
@@ -122,17 +126,12 @@ func (sp *SerialPort) OnWrite(mmu *mem.MMU, addr uint16, value byte) mem.MemWrit
 		sp.ctrl.Write(value)
 
 		if sp.ctrl.IsTransferEnabled() && sp.ctrl.IsClockInternal() {
-			cable := sp.host.SerialCable()
-
 			// TODO(GBC): derive this somehow and factor in GBC speeds when relevant
 			sp.clk = 8192
 
-			err := cable.WriteByte(sp.buf)
-			if err != nil {
-				sp.host.Log("Unable to write 0x%02X to serial cable: %v", value, err)
-			}
+			_ = sp.cable.WriteByte(sp.buf)
 
-			recvVal, err := cable.ReadByte()
+			recvVal, err := sp.cable.ReadByte()
 			if err != nil {
 				sp.recv = 0xFF
 			} else {

hardware/dmg.go

@@ -36,7 +36,7 @@ type DMG struct {
 	debuggerHandler mem.MemHandlerHandle
 }
 
-func NewDMG(host devices.HostInterface, opts ...DMGOption) (*DMG, error) {
+func NewDMG(opts ...DMGOption) (*DMG, error) {
 	cpu, err := cpu.NewCPU()
 	if err != nil {
 		return nil, err
@@ -54,7 +54,7 @@ func NewDMG(host devices.HostInterface, opts ...DMGOption) (*DMG, error) {
 		debugger:  debug.NewNullDebugger(),
 		ic:        devices.NewInterruptController(),
 		lcd:       devices.NewLCD(),
-		serial:    devices.NewSerialPort(host),
+		serial:    devices.NewSerialPort(),
 		timer:     devices.NewTimer(),
 	}
 
@@ -122,6 +122,7 @@ func (dmg *DMG) Run(host devices.HostInterface) error {
 	framebuffer := host.Framebuffer()
 	defer close(framebuffer)
 
+	dmg.serial.AttachCable(host.SerialCable())
 	dmg.debugger.Setup(dmg.cpu, dmg.mmu)
 
 	hostExit := host.Exited()

main.go

@@ -140,14 +140,13 @@ func initHost(options *CLIOptions) (host.Host, error) {
 	return hostDevice, nil
 }
 
-func initDMG(hostDevice host.Host, options *CLIOptions) (*hardware.DMG, error) {
+func initDMG(options *CLIOptions) (*hardware.DMG, error) {
 	debugger, err := debug.NewDebugger(options.debugger)
 	if err != nil {
 		return nil, fmt.Errorf("unable to initialize Debugger: %w", err)
 	}
 
 	dmg, err := hardware.NewDMG(
-		hostDevice,
 		hardware.WithDebugger(debugger),
 	)
 	if err != nil {
@@ -193,7 +192,7 @@ func runCart(options *CLIOptions) error {
 		return fmt.Errorf("unable to initialize host device: %w", err)
 	}
 
-	dmg, err := initDMG(hostDevice, options)
+	dmg, err := initDMG(options)
 	if err != nil {
 		return err
 	}