cartridge

Documentation

Overview

Package cartridge provides .nes ROM loading and saving.

Index

• func ControlBytes(battery, mirror, mapper byte, hasTrainer bool) (byte, byte)
• type Cartridge
  • func LoadFile(reader io.Reader) (*Cartridge, error)
  • func New() *Cartridge
  • func (c *Cartridge) Save(writer io.Writer) error
• type MirrorMode
  • func (m MirrorMode) NametableIndexes() [4]uint16

Functions

func ControlBytes

func ControlBytes(battery, mirror, mapper byte, hasTrainer bool) (byte, byte)

ControlBytes returns the 2 control bytes of the iNES header based on the cartridge configuration.

Types

type Cartridge

type Cartridge struct {
	PRG     []byte // PRG-ROM banks
	CHR     []byte // CHR-ROM banks
	RAM     byte   // PRG-RAM banks
	Trainer []byte

	Mapper      byte       // mapper type
	Mirror      MirrorMode // mirroring mode
	Battery     byte       // battery present
	VideoFormat byte       // 0 NTSC, 1 PAL
}

Cartridge contains a NES cartridge content.

func LoadFile

func LoadFile(reader io.Reader) (*Cartridge, error)

LoadFile loads an .nes file in iNES format.

func New

func New() *Cartridge

New returns a new cartridge.

func (*Cartridge) Save

func (c *Cartridge) Save(writer io.Writer) error

Save the cartridge content in iNES format.

type MirrorMode

type MirrorMode int

MirrorMode defines a mirror mode.

const (
	// MirrorHorizontal is a vertical arrangement of the nametables,
	// resulting in horizontal mirroring, which makes a 32x60 tilemap.
	MirrorHorizontal MirrorMode = iota
	// MirrorVertical is a horizontal arrangement of the nametables,
	// resulting in vertical mirroring, which makes a 64x30 tilemap.
	MirrorVertical
	// Single-screen mirroring is only available with certain mappers,
	// resulting in two 32x30 tilemaps.
	MirrorSingle0
	MirrorSingle1
	// Mirror4 offers 4 unique nametables can be addressed through the PPU bus,
	// creating a 64x60 tilemap, allowing for more flexible screen layouts.
	Mirror4
	MirrorDiagonal
	MirrorLShaped
	Mirror3Vertical
	Mirror3Horizontal
	Mirror3Diagonal
)

mirror modes.

func (MirrorMode) NametableIndexes

func (m MirrorMode) NametableIndexes() [4]uint16

NametableIndexes returns the nametable indexes of the mirror mode.