Trait System 

pub trait System {
    // Required methods
    fn read(&mut self, cpu: &mut W65C02S, addr: u16) -> u8;
    fn write(&mut self, cpu: &mut W65C02S, addr: u16, data: u8);

    // Provided methods
    fn read_opcode(&mut self, cpu: &mut W65C02S, addr: u16) -> u8 { ... }
    fn read_locked(&mut self, cpu: &mut W65C02S, addr: u16) -> u8 { ... }
    fn read_locked_spurious(&mut self, cpu: &mut W65C02S, addr: u16) { ... }
    fn read_vector(&mut self, cpu: &mut W65C02S, addr: u16) -> u8 { ... }
    fn write_stack(&mut self, cpu: &mut W65C02S, addr: u16, data: u8) { ... }
    fn write_locked(&mut self, cpu: &mut W65C02S, addr: u16, data: u8) { ... }
    fn read_opcode_spurious(&mut self, cpu: &mut W65C02S, addr: u16) { ... }
    fn read_operand(&mut self, cpu: &mut W65C02S, addr: u16) -> u8 { ... }
    fn read_operand_spurious(&mut self, cpu: &mut W65C02S, addr: u16) { ... }
    fn read_pointer(&mut self, cpu: &mut W65C02S, addr: u16) -> u8 { ... }
    fn read_stack(&mut self, cpu: &mut W65C02S, addr: u16) -> u8 { ... }
    fn read_stack_spurious(&mut self, cpu: &mut W65C02S, addr: u16) { ... }
    fn read_spurious(&mut self, cpu: &mut W65C02S, addr: u16) { ... }
}

Implements a system connected to a W65C02S’s bus. Only read and write need be implemented for a simple system, but other systems may be more complicated; for instance, many 65C02-based microcontrollers have advanced interrupt vectoring logic that would require implementing read_vector.

Required Methods

fn read(&mut self, cpu: &mut W65C02S, addr: u16) -> u8

Read a byte of data from the given address. SYNC is LOW and VPB and MLB are HIGH.

fn write(&mut self, cpu: &mut W65C02S, addr: u16, data: u8)

Write a byte of data to the given address. SYNC is LOW and VPB and MLB are HIGH.

Provided Methods

fn read_opcode(&mut self, cpu: &mut W65C02S, addr: u16) -> u8

Read an instruction opcode from the given address. VPB, MLB, and SYNC are all HIGH.

fn read_locked(&mut self, cpu: &mut W65C02S, addr: u16) -> u8

Read data from the given address as part of a Read-Modify-Write instruction. SYNC and MLB are LOW, VPB is HIGH.

fn read_locked_spurious(&mut self, cpu: &mut W65C02S, addr: u16)

Second data read from the given address as part of a Read-Modify-Write instruction. This data is ignored; this is an “idle cycle”. SYNC and MLB are LOW, VPB is HIGH. Indistinguishable from a locked data read on real hardware, but the distinction may be useful for simulation.

fn read_vector(&mut self, cpu: &mut W65C02S, addr: u16) -> u8

Read part of an interrupt vector from the given address. VPB is LOW, and SYNC and MLB are HIGH.

fn write_stack(&mut self, cpu: &mut W65C02S, addr: u16, data: u8)

Push a byte of data onto the stack at the given address. SYNC is LOW and VPB and MLB are HIGH. Indistinguishable from a normal data write on real hardware, but the distinction may be useful for simulation.

fn write_locked(&mut self, cpu: &mut W65C02S, addr: u16, data: u8)

Write a byte of data to the given address as the conclusion of a Read- Modify-Write instruction. SYNC and MLB are LOW, VPB is HIGH.

fn read_opcode_spurious(&mut self, cpu: &mut W65C02S, addr: u16)

Read an instruction opcode whose execution will be preempted by an interrupt or a reset, or which follows a WAI or STP instruction that has not yet been broken out of. VPB, MLB, and SYNC are all HIGH. Indistinguishable from a normal opcode fetch on real hardware, but the distinction may be useful for simulation.

fn read_operand(&mut self, cpu: &mut W65C02S, addr: u16) -> u8

Read an instruction operand from the given address. SYNC is LOW and VPB and MLB are HIGH. Indistinguishable from an ordinary data read on real hardware, but the distinction may be useful for simulation.

fn read_operand_spurious(&mut self, cpu: &mut W65C02S, addr: u16)

Read an instruction operand from the given address, except that the instruction had an implied operand or was preempted by a reset. SYNC is LOW and VPB and MLB are HIGH. Indistinguishable from an ordinary data read on real hardware, but the distinction may be useful for simulation.

fn read_pointer(&mut self, cpu: &mut W65C02S, addr: u16) -> u8

Read part of a pointer from the given address. SYNC is LOW and VPB and MLB are HIGH. Indistinguishable from an ordinary data read on real hardware, but the distinction may be useful for simulation.

fn read_stack(&mut self, cpu: &mut W65C02S, addr: u16) -> u8

Pop a value from the stack at the given address. SYNC is LOW and VPB and MLB are HIGH. Indistinguishable from an ordinary data read on real hardware, but the distinction may be useful for simulation.

fn read_stack_spurious(&mut self, cpu: &mut W65C02S, addr: u16)

Spurious stack “read” that occurs during reset. SYNC is LOW and VPB and MLB are HIGH. Indistinguishable from an ordinary data read on real hardware, but the distinction may be useful for simulation.

fn read_spurious(&mut self, cpu: &mut W65C02S, addr: u16)

Read a byte of data from the given address during an “internal operation” cycle. SYNC is LOW and VPB and MLB are HIGH. Indistinguishable from an ordinary data read on real hardware, but the distinction may be useful for simulation.

Implementors