Enum Cop0Access 

pub enum Cop0Access {
    Read {
        src: u8,
        dest: u8,
        wide: bool,
    },
    Cop1(Cop1Access),
    Tlb(TlbOp),
    Eret,
    Write {
        dest: u8,
        value: u64,
        wide: bool,
    },
}

A coprocessor access that EX resolved but must not itself perform.

Despite the name this now covers COP0, the TLB and COP1 control (Cop1). They share a variant because they share the stage split below, not because they are the same unit — the name is kept for churn reasons and this note exists so it does not mislead as COP1 grows in Sprint 3.

The stage split is the manual’s, not a convenience: UM §4.6.9 describes the CP0 bypass interlock as firing when “an instruction which caused an exception reaches the WB stage and the subsequent instruction in the DC stage requests a read of any CP0 register” — so a coprocessor read happens in DC and a write happens in WB. Performing both in EX would make that interlock unexpressible, which is the same mistake ADR 0007 exists to prevent one level up.

Variants

Read

Read COP0 register src into GPR dest, in DC.

Fields

src: u8

COP0 register number.

dest: u8

GPR destination.

wide: bool

64-bit (DMFC0) rather than 32-bit sign-extended (MFC0).

Cop1(Cop1Access)

A COP1 control access, performed where the state lives.

Tlb(TlbOp)

A TLB instruction. Performed where the TLB lives, not in EX.

Eret

ERET — restore PC from EPC/ErrorEPC, clear EXL/ERL, clear the link bit.

Cannot be resolved in EX like an ordinary redirect, because the target comes out of COP0 rather than out of the instruction.

Write

Write value to COP0 register dest, in WB.

Fields

dest: u8

COP0 register number.

value: u64

Value from rt.

wide: bool

64-bit (DMTC0) rather than 32-bit (MTC0).

Trait Implementations

impl Clone for Cop0Access

fn clone(&self) -> Cop0Access

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Cop0Access

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Cop0Access

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Cop0Access

fn eq(&self, other: &Cop0Access) -> 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 Serialize for Cop0Access

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Copy for Cop0Access

impl Eq for Cop0Access

impl StructuralPartialEq for Cop0Access