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cartridge.go
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cartridge.go
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// This file is part of Gopher2600.
//
// Gopher2600 is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Gopher2600 is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Gopher2600. If not, see <https://www.gnu.org/licenses/>.
package cartridge
import (
"fmt"
"strings"
"github.com/jetsetilly/gopher2600/cartridgeloader"
"github.com/jetsetilly/gopher2600/errors"
"github.com/jetsetilly/gopher2600/hardware/memory/bus"
"github.com/jetsetilly/gopher2600/hardware/memory/cartridge/banks"
"github.com/jetsetilly/gopher2600/hardware/memory/cartridge/harmony"
"github.com/jetsetilly/gopher2600/hardware/memory/cartridge/supercharger"
"github.com/jetsetilly/gopher2600/hardware/memory/memorymap"
)
// Cartridge defines the information and operations for a VCS cartridge
type Cartridge struct {
bus.DebugBus
bus.CPUBus
Filename string
Hash string
// the specific cartridge data, mapped appropriately to the memory
// interfaces
mapper cartMapper
// when cartridge is in passive mode, cartridge hotspots do not work. We
// send the passive value to the Read() and Write() functions of the mapper
// and we also use it to prevent the Listen() function from triggering.
// Useful for disassembly when we don't want the cartridge to react.
Passive bool
}
// NewCartridge is the preferred method of initialisation for the cartridge
// type
func NewCartridge() *Cartridge {
cart := &Cartridge{}
cart.Eject()
return cart
}
func (cart Cartridge) String() string {
return cart.Filename
}
// MappingSummary returns a current string summary of the mapper
func (cart Cartridge) MappingSummary() string {
return fmt.Sprintf("%s", cart.mapper)
}
// ID returns the cartridge mapping ID
func (cart Cartridge) ID() string {
return cart.mapper.ID()
}
// Peek is an implementation of memory.DebugBus. Address must be normalised.
func (cart *Cartridge) Peek(addr uint16) (uint8, error) {
return cart.mapper.Read(addr&memorymap.CartridgeBits, false)
}
// Poke is an implementation of memory.DebugBus. Address must be normalised.
func (cart *Cartridge) Poke(addr uint16, data uint8) error {
return cart.mapper.Write(addr&memorymap.CartridgeBits, data, false, true)
}
// Patch writes to cartridge memory. Offset is measured from the start of
// cartridge memory. It differs from Poke in that respect
func (cart *Cartridge) Patch(offset int, data uint8) error {
return cart.mapper.Patch(offset, data)
}
// Read is an implementation of memory.CPUBus. Address should not be
// normalised.
func (cart *Cartridge) Read(addr uint16) (uint8, error) {
if _, ok := cart.mapper.(*supercharger.Supercharger); ok {
return cart.mapper.Read(addr, cart.Passive)
}
return cart.mapper.Read(addr&memorymap.CartridgeBits, cart.Passive)
}
// Write is an implementation of memory.CPUBus. Address should not be
// normalised.
func (cart *Cartridge) Write(addr uint16, data uint8) error {
if _, ok := cart.mapper.(*supercharger.Supercharger); ok {
return cart.mapper.Write(addr, data, cart.Passive, false)
}
return cart.mapper.Write(addr&memorymap.CartridgeBits, data, cart.Passive, false)
}
// Eject removes memory from cartridge space and unlike the real hardware,
// attaches a bank of empty memory - for convenience of the debugger
func (cart *Cartridge) Eject() {
cart.Filename = "ejected"
cart.Hash = ""
cart.mapper = newEjected()
}
// IsEjected returns true if no cartridge is attached
func (cart *Cartridge) IsEjected() bool {
_, ok := cart.mapper.(*ejected)
return ok
}
// Attach the cartridge loader to the VCS and make available the data to the CPU
// bus
//
// How cartridges are mapped into the VCS's 4k space can differs dramatically.
// Much of the implementation details have been cribbed from Kevin Horton's
// "Cart Information" document [sizes.txt]. Other sources of information noted
// as appropriate.
func (cart *Cartridge) Attach(cartload cartridgeloader.Loader) error {
data, err := cartload.Load()
if err != nil {
return err
}
// note name of cartridge
cart.Filename = cartload.Filename
cart.Hash = cartload.Hash
cart.mapper = newEjected()
cartload.Mapping = strings.ToUpper(cartload.Mapping)
if cartload.Mapping == "" || cartload.Mapping == "AUTO" {
return cart.fingerprint(data)
}
addSuperchip := false
switch cartload.Mapping {
case "2k":
cart.mapper, err = newAtari2k(data)
case "4k":
cart.mapper, err = newAtari4k(data)
case "F8":
cart.mapper, err = newAtari8k(data)
case "F6":
cart.mapper, err = newAtari16k(data)
case "F4":
cart.mapper, err = newAtari32k(data)
case "2k+":
cart.mapper, err = newAtari2k(data)
addSuperchip = true
case "4k+":
cart.mapper, err = newAtari4k(data)
addSuperchip = true
case "F8+":
cart.mapper, err = newAtari8k(data)
addSuperchip = true
case "F6+":
cart.mapper, err = newAtari16k(data)
addSuperchip = true
case "F4+":
cart.mapper, err = newAtari32k(data)
addSuperchip = true
case "FA":
cart.mapper, err = newCBS(data)
case "FE":
// !!TODO: FE cartridge mapping
case "E0":
cart.mapper, err = newParkerBros(data)
case "E7":
cart.mapper, err = newMnetwork(data)
case "3F":
cart.mapper, err = newTigervision(data)
case "AR":
cart.mapper, err = supercharger.NewSupercharger(data)
case "DPC":
cart.mapper, err = newDPC(data)
case "DPC+":
cart.mapper, err = harmony.NewDPCplus(data)
}
if addSuperchip {
if superchip, ok := cart.mapper.(optionalSuperchip); ok {
if !superchip.addSuperchip() {
err = errors.New(errors.CartridgeError, "error adding superchip")
}
} else {
err = errors.New(errors.CartridgeError, "error adding superchip")
}
}
return err
}
// Initialise the cartridge
func (cart *Cartridge) Initialise() {
cart.mapper.Initialise()
}
// NumBanks returns the number of banks in the catridge
func (cart Cartridge) NumBanks() int {
return cart.mapper.NumBanks()
}
// GetBank returns the current bank information for the specified address. See
// documentation for memorymap.Bank for more information.
func (cart Cartridge) GetBank(addr uint16) banks.Details {
if addr&memorymap.OriginCart != memorymap.OriginCart {
return banks.Details{NonCart: true}
}
return cart.mapper.GetBank(addr & memorymap.CartridgeBits)
}
// Listen for data at the specified address.
//
// The VCS cartridge port is wired up to all 13 address lines of the 6507.
// Under normal operation, the chip-select line is used by the cartridge to
// know when to put data on the data bus. If it's not "on" then the cartridge
// does nothing.
//
// However, the option is there to "listen" on the address bus. Notably the
// tigervision (3F) mapping listens for address 0x003f, which is in the TIA
// address space. When this address is triggered, the tigervision cartridge
// will use whatever is on the data bus to switch banks.
func (cart Cartridge) Listen(addr uint16, data uint8) {
if !cart.Passive {
cart.mapper.Listen(addr, data)
}
}
// Step should be called every CPU cycle. The attached cartridge may or may not
// change its state as a result. In fact, very few cartridges care about this.
func (cart Cartridge) Step() {
cart.mapper.Step()
}
// GetRegistersBus returns interface to the debugging bus to the cartridge.
func (cart Cartridge) GetRegistersBus() bus.CartRegistersBus {
if bus, ok := cart.mapper.(bus.CartRegistersBus); ok {
return bus
}
return nil
}
// GetStaticBus returns interface to the debugging bus to the cartridge.
func (cart Cartridge) GetStaticBus() bus.CartStaticBus {
if bus, ok := cart.mapper.(bus.CartStaticBus); ok {
return bus
}
return nil
}
// GetRAMbus returns an array of bus.CartRAM or nil if catridge contains no RAM
func (cart Cartridge) GetRAMbus() bus.CartRAMbus {
if bus, ok := cart.mapper.(bus.CartRAMbus); ok {
return bus
}
return nil
}
// IterateBanks returns the sequence of banks in a cartridge. To return the
// next bank in the sequence, call the function with the instance of
// banks.Content returned from the previous call. The end of the sequence is
// indicated by the nil value. Start a new iteration with the nil argument.
func (cart Cartridge) IterateBanks(prev *banks.Content) (*banks.Content, error) {
// to keep the mappers as neat as possible, handle the nil special condition here
if prev == nil {
prev = &banks.Content{Number: -1}
}
return cart.mapper.IterateBanks(prev), nil
}