z80

type CPU struct {
	States

	Memory Memory
	IO     IO

	// RETNHandle is called when CPU execute a RETN op.
	RETNHandler RETNHandler
	// RETIHandle is called when CPU execute a RETI op.
	RETIHandler RETIHandler

	// Interrupt is a signal to interrupt.  When you set non-nil value, then
	// CPU.Step and CPU.Run treat it as one of Z80 interruptions.
	Interrupt *Interrupt

	BreakPoints map[uint16]struct{}

	// HALT indicates whether the last Run() is terminated with HALT op.
	HALT bool
}

type DumbIO []uint8

type DumbMemory []uint8

type Flag uint8

type GPR struct {
	AF Register
	BC Register
	DE Register
	HL Register
}

type INT interface {
	// CheckINT should return valid interruption data if maskable interruption
	// made. The data is used for interruption codes or as a vector depending
	// on interruption mode.
	CheckINT() []uint8

	// ReturnINT is called when "RETI" op is executed.
	ReturnINT()
}

type IO interface {
	In(addr uint8) uint8
	Out(addr uint8, value uint8)
}

type Interrupt struct {
	Type InterruptType
	Data []uint8
}

type InterruptType int

type MapMemory map[uint16]uint8

type Memory interface {
	Get(addr uint16) uint8
	Set(addr uint16, value uint8)
}

type NMI interface {
	// CheckNMI should return true if non-maskable interruption made.
	CheckNMI() bool

	// ReturnNMI is called when "RETN" op is executed.
	ReturnNMI()
}

type RETIHandler interface {
	RETIHandle()
}

type RETNHandler interface {
	RETNHandle()
}

type Register struct {
	Hi uint8
	Lo uint8
}

type SPR struct {
	IR Register
	IX uint16
	IY uint16
	SP uint16
	PC uint16
}

type States struct {
	GPR
	SPR

	Alternate GPR

	IFF1 bool
	IFF2 bool
	IM   int
}