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//! Serial traits

/// Serial error
pub trait Error: core::fmt::Debug {
    /// Convert error to a generic serial error kind
    ///
    /// By using this method, serial errors freely defined by HAL implementations
    /// can be converted to a set of generic serial errors upon which generic
    /// code can act.
    fn kind(&self) -> ErrorKind;
}

impl Error for core::convert::Infallible {
    fn kind(&self) -> ErrorKind {
        match *self {}
    }
}

/// Serial error kind
///
/// This represents a common set of serial operation errors. HAL implementations are
/// free to define more specific or additional error types. However, by providing
/// a mapping to these common serial errors, generic code can still react to them.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
#[non_exhaustive]
pub enum ErrorKind {
    /// The peripheral receive buffer was overrun.
    Overrun,
    /// Received data does not conform to the peripheral configuration.
    /// Can be caused by a misconfigured device on either end of the serial line.
    FrameFormat,
    /// Parity check failed.
    Parity,
    /// Serial line is too noisy to read valid data.
    Noise,
    /// A different error occurred. The original error may contain more information.
    Other,
}

impl Error for ErrorKind {
    fn kind(&self) -> ErrorKind {
        *self
    }
}

impl core::fmt::Display for ErrorKind {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        match self {
            Self::Overrun => write!(f, "The peripheral receive buffer was overrun"),
            Self::Parity => write!(f, "Parity check failed"),
            Self::Noise => write!(f, "Serial line is too noisy to read valid data"),
            Self::FrameFormat => write!(
                f,
                "Received data does not conform to the peripheral configuration"
            ),
            Self::Other => write!(
                f,
                "A different error occurred. The original error may contain more information"
            ),
        }
    }
}

/// Serial error type trait
///
/// This just defines the error type, to be used by the other traits.
pub trait ErrorType {
    /// Error type
    type Error: Error;
}

impl<T: ErrorType> ErrorType for &mut T {
    type Error = T::Error;
}

/// Write half of a serial interface (blocking variant)
pub trait Write<Word: Copy = u8>: ErrorType {
    /// Writes a slice, blocking until everything has been written
    ///
    /// An implementation can choose to buffer the write, returning `Ok(())`
    /// after the complete slice has been written to a buffer, but before all
    /// words have been sent via the serial interface. To make sure that
    /// everything has been sent, call [`flush`] after this function returns.
    ///
    /// [`flush`]: #tymethod.flush
    fn write(&mut self, buffer: &[Word]) -> Result<(), Self::Error>;

    /// Block until the serial interface has sent all buffered words
    fn flush(&mut self) -> Result<(), Self::Error>;
}

impl<T: Write<Word>, Word: Copy> Write<Word> for &mut T {
    fn write(&mut self, buffer: &[Word]) -> Result<(), Self::Error> {
        T::write(self, buffer)
    }

    fn flush(&mut self) -> Result<(), Self::Error> {
        T::flush(self)
    }
}