supercharger

Documentation

Overview

Package supercharger implements the tape based cartridge format. The implementation is complex enough for it to be spread over more than one file and so for purposes of clarity it has been placed in its own package.

The supercharger is interfaced in the same way as other cartridge formats. The fastload mechanism however, requires special handling, which is unfortunate but unavoidable. It is worth summarising here:

As a result of a fast-load of a BIN file into supercharger memory, the supercharger package will return an error of type supercharger.FastLoaded

The FastLoaded error indicates an exception to the normal running of the emulation. For the loading to complete the error needs special handling. There are two places in Gopher2600 where this handling takes place. One is in the debugger.inputLoop() and the other in hardware.run() (the latter is called from the playmode package).

Wherever it is handled, the error should be caught and interpreted as a function and called, with a reference to the emulator's CPU, RAM and Timer.

Index

• Constants
• type FastLoad
  • func (tap *FastLoad) Load() error
• type FastLoaded
  • func (er FastLoaded) Error() string
• type Registers
  • func (r Registers) BankString() string
  • func (r Registers) String() string
• type Supercharger
  • func NewSupercharger(data []byte) (*Supercharger, error)
  • func (cart Supercharger) GetBank(addr uint16) banks.Details
  • func (cart Supercharger) GetRAM() []bus.CartRAM
  • func (cart Supercharger) GetRegisters() bus.CartRegisters
  • func (cart Supercharger) ID() string
  • func (cart *Supercharger) Initialise()
  • func (cart Supercharger) IterateBanks(prev *banks.Content) *banks.Content
  • func (cart *Supercharger) Listen(addr uint16, _ uint8)
  • func (cart Supercharger) NumBanks() int
  • func (cart *Supercharger) Patch(_ int, _ uint8) error
  • func (cart *Supercharger) PutRAM(bank int, idx int, data uint8)
  • func (cart *Supercharger) PutRegister(register string, data string)
  • func (cart *Supercharger) Read(fullAddr uint16, passive bool) (uint8, error)
  • func (cart *Supercharger) Step()
  • func (cart Supercharger) String() string
  • func (cart *Supercharger) Write(addr uint16, data uint8, passive bool, poke bool) error
• type Tape
  • func NewFastLoad(cart *Supercharger, data interface{}) (Tape, error)

Constants

const MappingID = "AR"

Types

type FastLoad

type FastLoad struct {
	// contains filtered or unexported fields
}

FastLoad implements the Tape interface. It loads data from a binary file rather than a sound file.

On success it returns the FastLoaded error. This must be interpreted by the emulator driver and called with the arguments listed in the error type.

Format information for fast-loca binary rom mailing list post:

Subject: Re: [stella] Supercharger BIN format From: Eckhard Stolberg Date: Fri, 08 Jan 1999

func (*FastLoad) Load

func (tap *FastLoad) Load() error

Load implements the Tape interface

type FastLoaded

type FastLoaded func(*cpu.CPU, *vcs.RAM, *timer.Timer) error

FastLoaded error is returned on success of FastLoad.Load(). It must be honoured (ie. caught and the function called) by the driving emulator for the fastload process to complete.

It is unusual to use an error in this way but this is the only effective way of sending a signal that something unusual has happened. In that sense, it is an error, the normal run of the emulator has been interrupted and must be handled.

That there is nothing else like this in the 2600 emulation, using an error like this is justified. It is an exception to the rule, so to speak, and setting up another way of sending the "fast load completed" signal is inappropriate.

func (FastLoaded) Error

func (er FastLoaded) Error() string

type Registers

type Registers struct {
	Value uint8
	Delay int // 0=off, 1=trigger

	// the last value to be written to (not including fff8 writes)
	LastWriteValue   uint8
	LastWriteAddress uint16

	// config byte, raw value
	ConfigByte uint8

	// config byte broken into parts
	WriteDelay  int
	BankingMode int
	RAMwrite    bool
	ROMpower    bool
	// contains filtered or unexported fields
}

Registers implements the bus.CartRegisters interface

func (Registers) BankString

func (r Registers) BankString() string

BankString is like string but just the bank information. we use this when building the mapper summary, the String() function is too verbose for that

func (Registers) String

func (r Registers) String() string

type Supercharger

type Supercharger struct {
	// contains filtered or unexported fields
}

Supercharger represents a supercharger cartridge

func NewSupercharger

func NewSupercharger(data []byte) (*Supercharger, error)

NewSupercharger is the preferred method of initialisation for the Supercharger type

func (Supercharger) GetBank

func (cart Supercharger) GetBank(addr uint16) banks.Details

GetBank implements the cartMapper interface

func (Supercharger) GetRAM

func (cart Supercharger) GetRAM() []bus.CartRAM

GetRAM implements the bus.CartRAMBus interface

func (Supercharger) GetRegisters

func (cart Supercharger) GetRegisters() bus.CartRegisters

GetRegisters implements the bus.CartDebugBus interface

func (Supercharger) ID

func (cart Supercharger) ID() string

ID implements the cartMapper interface

func (*Supercharger) Initialise

func (cart *Supercharger) Initialise()

Initialise implements the cartMapper interface

func (Supercharger) IterateBanks

func (cart Supercharger) IterateBanks(prev *banks.Content) *banks.Content

IterateBank implemnts the disassemble interface

func (*Supercharger) Listen

func (cart *Supercharger) Listen(addr uint16, _ uint8)

Listen implements the cartMapper interface

func (Supercharger) NumBanks

func (cart Supercharger) NumBanks() int

NumBanks implements the cartMapper interface

func (*Supercharger) Patch

func (cart *Supercharger) Patch(_ int, _ uint8) error

Patch implements the cartMapper interface

func (*Supercharger) PutRAM

func (cart *Supercharger) PutRAM(bank int, idx int, data uint8)

PutRAM implements the bus.CartRAMBus interface

func (*Supercharger) PutRegister

func (cart *Supercharger) PutRegister(register string, data string)

PutRegister implements the bus.CartDebugBus interface

Register specification is divided with the "::" string. The following table describes what the valid register strings and, after the = sign, the type to which the data argument will be converted.

value = int
delay = int (0 ... 6)
ramwrite = bool
rompower = bool

note that PutRegister() will panic() if the register or data string is invalid.

func (*Supercharger) Read

func (cart *Supercharger) Read(fullAddr uint16, passive bool) (uint8, error)

Read implements the cartMapper interface

func (*Supercharger) Step

func (cart *Supercharger) Step()

Step implements the cartMapper interface

func (Supercharger) String

func (cart Supercharger) String() string

func (*Supercharger) Write

func (cart *Supercharger) Write(addr uint16, data uint8, passive bool, poke bool) error

Write implements the cartMapper interface

type Tape

type Tape interface {
	Load() error
}

Tape defines the operations required by the $fff9 tape loader. With this interface, the Supercharger implementation supports both fast-loading from a Stella bin file, and "slow" loading from a sound file.

func NewFastLoad

func NewFastLoad(cart *Supercharger, data interface{}) (Tape, error)

NewFastLoad is the preferred method of initialisation for the FastLoad type