Enum BitOutcome 

#[repr(u8)]
pub enum BitOutcome {
    Clean = 0,
    Corrected = 1,
    Uncorrected = 2,
    Introduced = 3,
}

What the channel and the inner decoder each did to one coded bit.

Derived by comparing three bit-streams in the coded-bit index space — what the transmitter sent, what arrived at the demapper, and what the inner decoder’s own output re-encodes to:

State	arrived correct	decoder agrees	Meaning
Clean	yes	yes	the channel did not touch it
Corrected	no	yes	the inner code fixed it
Uncorrected	no	no	arrived wrong, still wrong — the outer code’s problem now
Introduced	yes	no	arrived right, the decoder broke it

Introduced is not padding for the fourth cell. A belief-propagation decoder that fails to converge flips correct bits, and one that does so at high SNR is broken. Having the state means the map can show that; folding it into Uncorrected would hide the symptom in with its opposite.

Variants

Clean = 0

Arrived correct and the decoder left it correct.

Corrected = 1

Arrived wrong; the inner decoder fixed it.

Uncorrected = 2

Arrived wrong and the inner decoder did not fix it.

Introduced = 3

Arrived correct and the inner decoder broke it.

Implementations

impl BitOutcome

pub fn arrived_wrong(self) -> bool

Whether the channel corrupted this bit — i.e. anything but Clean or Introduced.

Counting these over a frame and dividing by its coded-bit count reproduces channel_ber exactly: the map is that rate’s per-bit expansion, not a second measurement of it.

This says nothing about the decoder. Both states it matches mean “arrived wrong”; whether the decoder then fixed it is the other half of the map, and decoder_disagreed is how to ask. A consumer checking only this one is blind to the estimate stream entirely — see that method’s note.

pub fn decoder_disagreed(self) -> bool

Whether the inner decoder’s output still disagrees with the truth at this bit — i.e. Uncorrected or Introduced.

The dual of arrived_wrong: that one is the channel’s half of the map, this is the decoder’s. Both halves need a name, because this predicate is the map’s whole meaning and a consumer that spells it out by hand can get it subtly wrong with nothing to say so.

The two are independent, not complementary. Corrected is arrived_wrong && !decoder_disagreed; Introduced is the reverse; a bit can be both (Uncorrected) or neither (Clean).

Trait Implementations

impl Clone for BitOutcome

fn clone(&self) -> BitOutcome

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for BitOutcome

impl Debug for BitOutcome

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

Formats the value using the given formatter.

impl Default for BitOutcome

fn default() -> BitOutcome

Returns the “default value” for a type.

impl Eq for BitOutcome

impl PartialEq for BitOutcome

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for BitOutcome