memory

type AddChips func(maria Area, tia Area, riot Area)

type Area interface {
	Label() string

	// all valid memory areas must have an implementation of the Access()
	// function
	//
	// the write parameter represents the stats of the R/W line in the console.
	// individual memory areas can ignore this if it is not required or not
	// connected (2600 cartridge types)
	//
	// the address_or_idx parameter is either the raw unmapped address or an
	// index relative to the origin of the memory area. implementations of the
	// Area interface should make this clear by appropriate naming of the parameter.
	// more practically, the value of address_or_idx can be obtained through the
	// MapAddress() function
	//
	// the data parameter is the state of the data bus at the time of the call.
	// the write parameter indicates if the bus is being driven by the CPU at
	// the time of access (write will be true)
	//
	// the state of the data bus is returned along with an error. if the memory
	// area is not driving the data bus then the supplied data bus value should
	// be returned unchanged
	//
	// in rare cases where a memory area drives the data bus while the write
	// parameter is true (ie. the CPU is also driving the data bus) the conflict
	// should be resolved in the area implementation
	//
	// NOTE: the Access() function is provided instead of a separate Read/Write
	// functions. individual areas may have Read/Write functions for other
	// purposes (eg. the PEEK and POKE commands in a debugger) but these are not
	// necessary for emulation of memory
	//
	// for the more direct type of access the package level Read() and Write()
	// functions are provided
	Access(write bool, address_or_idx uint16, data uint8) (uint8, error)
}

type Context interface {
	ram.Context
	external.Context
	inptctrl.Context
	Spec() spec.Spec
}

type Memory struct {
	BIOS     *bios.BIOS
	INPTCTRL *inptctrl.INPTCTRL
	RAM7800  *ram.RAM
	RAMRIOT  *ram.RAM
	External *external.Device

	MARIA Area
	TIA   Area
	RIOT  Area

	// the last Area that was read from and written to
	LastRead  Area
	LastWrite Area

	// the following are only used by the debugger
	LastCPUAddress uint16
	LastCPUData    uint8
	LastCPUWrite   bool
	// contains filtered or unexported fields
}