goapple2/cards/firmware.go

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package cards
import (
"fmt"
)
type FirmwareCard struct {
name string
rom [12288]byte
cm CardManager
slot byte
slotbit byte
}
func NewFirmwareCard(rom []byte, name string, slot byte, cm CardManager) (*FirmwareCard, error) {
if len(rom) != 12288 {
return nil, fmt.Errorf("Wrong size ROM: expected 12288, got %d", len(rom))
}
fc := &FirmwareCard{name: name, cm: cm, slot: slot, slotbit: 1 << slot}
copy(fc.rom[:], rom)
return fc, nil
}
func (fc *FirmwareCard) String() string {
return fmt.Sprintf("%s (slot %d)", fc.name, fc.slot)
}
func (fc *FirmwareCard) Slot() byte {
return fc.slot
}
func (fc *FirmwareCard) ROMDisabled() {
// Firmware card doesn't have a $C(8-F)xx ROM
}
func (fc *FirmwareCard) handleAccess(address byte) {
if address%2 == 1 {
// Card off
fc.cm.HandleROM(false, fc.slotbit)
} else {
// Card on
fc.cm.HandleROM(true, fc.slotbit)
}
}
func (fc *FirmwareCard) Read16(address byte) byte {
fc.handleAccess(address)
return fc.cm.EmptyRead()
}
func (fc *FirmwareCard) Write16(address byte, value byte) {
fc.handleAccess(address)
}
func (fc *FirmwareCard) Read(address uint16) byte {
if address < 0xD000 {
panic(fmt.Sprintf("%s got read to $%04X (<$D000)", fc.String(), address))
}
return fc.rom[address-0xD000]
}
func (fc *FirmwareCard) Write(address uint16, value byte) {
// Firmware is ROM: do nothing
}
func (fc *FirmwareCard) Read256(address byte) byte {
return fc.cm.EmptyRead()
}
func (fc *FirmwareCard) Write256(address byte, value byte) {
// Firmware is ROM: do nothing
}