rusty-modbus-codec 0.1.0

Modbus sans-IO encode/decode codec (no_std)
Documentation 
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//! FIFO queue request: FC 18 (Read FIFO Queue).

use rusty_modbus_types::{Address, FunctionCode};

use crate::error::{DecodeError, EncodeError};
use crate::request::Encode;

/// FC 0x18 — Read FIFO Queue request.
///
/// Reads the contents of the FIFO queue at the given pointer address.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct ReadFifoQueueRequest {
    /// FIFO pointer address.
    pub fifo_pointer_address: Address,
}

impl ReadFifoQueueRequest {
    /// Decode from PDU data after the function code byte.
    ///
    /// # Errors
    ///
    /// Returns [`DecodeError::Truncated`] if `data` is shorter than 2 bytes.
    /// Returns [`DecodeError::LengthMismatch`] if `data` has extra bytes.
    pub fn decode(data: &[u8]) -> Result<Self, DecodeError> {
        DecodeError::check_exact_len(data, 2)?;
        let fifo_pointer_address = Address(u16::from_be_bytes([data[0], data[1]]));
        Ok(Self {
            fifo_pointer_address,
        })
    }
}

impl Encode for ReadFifoQueueRequest {
    fn encode_into(&self, buf: &mut [u8]) -> Result<usize, EncodeError> {
        let len = self.encoded_len();
        if buf.len() < len {
            return Err(EncodeError::BufferTooSmall {
                required: len,
                available: buf.len(),
            });
        }
        EncodeError::check_pdu_len(len)?;
        buf[0] = FunctionCode::ReadFifoQueue.code();
        buf[1..3].copy_from_slice(&self.fifo_pointer_address.0.to_be_bytes());
        Ok(len)
    }

    fn encoded_len(&self) -> usize {
        3
    }
}