Enum InstructionType 

pub enum InstructionType {
    Read,
    Write,
    ReadModifyWrite,
    Implied,
    Accumulator,
    Branch,
    JumpAbsolute,
    JumpIndirect,
    JumpSubroutine,
    ReturnSubroutine,
    ReturnInterrupt,
    Push,
    Pull,
    Break,
    Jam,
}

Instruction execution pattern classification.

Different instruction types follow different state sequences:

• Read: Fetch operand, read from effective address
• Write: Fetch operand, write to effective address
• ReadModifyWrite: Read, dummy write old, write new
• etc.

Variants

Read

Read instructions (LDA, LDX, LDY, AND, ORA, EOR, CMP, ADC, SBC, BIT, LAX, etc.)

Write

Write instructions (STA, STX, STY, SAX, SHA, SHX, SHY, TAS)

ReadModifyWrite

Read-Modify-Write (ASL, LSR, ROL, ROR, INC, DEC, SLO, RLA, SRE, RRA, DCP, ISC)

Implied

Implied/Register operations (TAX, INX, CLC, NOP, etc.) Single-byte instructions with internal operation

Accumulator

Accumulator operations (ASL A, LSR A, ROL A, ROR A) Two-cycle, single-byte

Branch

Branch instructions (BEQ, BNE, BCC, BCS, BPL, BMI, BVC, BVS) 2/3/4 cycles depending on condition and page crossing

JumpAbsolute

Jump Absolute (JMP $NNNN) 3 cycles

JumpIndirect

Jump Indirect (JMP ($NNNN)) 5 cycles

JumpSubroutine

Jump to Subroutine (JSR $NNNN) 6 cycles

ReturnSubroutine

Return from Subroutine (RTS) 6 cycles

ReturnInterrupt

Return from Interrupt (RTI) 6 cycles

Push

Push to Stack (PHA, PHP) 3 cycles

Pull

Pull from Stack (PLA, PLP) 4 cycles

Break

Software Interrupt (BRK) 7 cycles

Jam

JAM/KIL - Halt CPU

Implementations

impl InstructionType

pub const fn base_cycles(&self) -> u8

Returns the base number of cycles for this instruction type. This does not include addressing mode cycles or penalties.

pub const fn has_page_cross_penalty(&self) -> bool

Returns true if this instruction type can have page crossing penalty.

pub const fn is_rmw(&self) -> bool

Returns true if this is a read-modify-write instruction.

pub const fn from_opcode(opcode: u8) -> Self

Classify an opcode into its instruction type.

This function maps all 256 opcodes (official and unofficial) to their execution pattern type, enabling proper cycle-by-cycle state machine dispatch.

Trait Implementations

impl Clone for InstructionType

fn clone(&self) -> InstructionType

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for InstructionType

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for InstructionType

fn default() -> InstructionType

Returns the “default value” for a type.

impl PartialEq for InstructionType

fn eq(&self, other: &InstructionType) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for InstructionType

impl Eq for InstructionType

impl StructuralPartialEq for InstructionType