Enum WriteOrigin 

pub enum WriteOrigin {
    Instruction,
    Reset,
}

What performed a register write.

Not every write to $4000-$4017 comes from an instruction, and a provenance tool that pretends otherwise is worse than no tool. Apu::reset performs an internal write_register($4015, 0) modelling the warm-reset silencing of the channels. That is real hardware behaviour with no CPU instruction behind it, and attributing it to whatever PC happened to be latched would print a confident, specific, wrong answer — the exact failure this feature exists to prevent, reproduced by the feature itself.

Found in review of the PR that introduced audio provenance, before it shipped. The alternative fixes were both worse: suppressing the record entirely would leave the slot advertising the register’s previous value after reset genuinely changed it, and a sentinel PC would be indistinguishable from a real write to address zero.

Variants

Instruction

A CPU instruction wrote it; pc names that instruction.

Reset

The APU’s own reset sequence wrote it. pc is not meaningful.

Trait Implementations

impl Clone for WriteOrigin

fn clone(&self) -> WriteOrigin

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for WriteOrigin

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

Formats the value using the given formatter.

impl Default for WriteOrigin

fn default() -> WriteOrigin

Returns the “default value” for a type.

impl Hash for WriteOrigin

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for WriteOrigin

fn eq(&self, other: &WriteOrigin) -> 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 WriteOrigin

impl Eq for WriteOrigin

impl StructuralPartialEq for WriteOrigin