wireparse 0.1.0

Library for reading and writing ethernet and other related protocals.
Documentation 
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use core::mem::MaybeUninit;

use crate::error::{NetpackError, Result};

pub trait CheckedReader: Sized {
    fn read_slice_checked(&mut self, size: usize) -> Result<&[u8]>;
    #[inline(always)]
    fn read_checked<T: ReadDataChecked>(&mut self) -> Result<T> {
        T::read_checked(self)
    }
}

pub trait CheckedWriter: Sized {
    fn write_slice(&mut self, data: &[u8]) -> Result<()>;
    #[inline(always)]
    fn write<T: WriteDataChecked>(&mut self, value: T) -> Result<()> {
        T::write_to_checked(value, self)
    }
}

impl<'a> CheckedReader for &'a [u8] {
    #[inline(always)]
    fn read_slice_checked(&mut self, size: usize) -> Result<&'a [u8]> {
        if self.len() < size {
            return Err(NetpackError::BufferTooSmall {
                provided_size: self.len(),
                requried_size: size,
            });
        }
        let (data, remaining) = self.split_at(size);
        *self = remaining;
        Ok(data)
    }
}

impl<'a> CheckedWriter for &'a mut [u8] {
    #[inline(always)]
    fn write_slice(&mut self, data: &[u8]) -> Result<()> {
        if self.len() < data.len() {
            return Err(NetpackError::BufferTooSmall {
                provided_size: self.len(),
                requried_size: data.len(),
            });
        }
        let this = core::mem::take(self);
        let (write_buffer, remaining) = this.split_at_mut(data.len());
        *self = remaining;
        write_buffer.copy_from_slice(data);
        Ok(())
    }
}

pub trait ReadDataChecked: Sized {
    fn read_checked(reader: &mut impl CheckedReader) -> Result<Self>;
}

pub trait WriteDataChecked {
    fn write_to_checked(self, writer: &mut impl CheckedWriter) -> Result<()>;
}

impl<const N: usize> ReadDataChecked for [u8; N] {
    #[cfg_attr(feature = "fast-rw", inline(always))]
    fn read_checked(reader: &mut impl CheckedReader) -> Result<Self> {
        let slice = reader.read_slice_checked(N)?;
        unsafe { Ok(*slice.as_ptr().cast()) }
    }
}

impl<const N: usize> WriteDataChecked for [u8; N] {
    fn write_to_checked(self, writer: &mut impl CheckedWriter) -> Result<()> {
        writer.write_slice(&self)
    }
}

impl<const N: usize> ReadDataChecked for [u16; N] {
    fn read_checked(reader: &mut impl CheckedReader) -> Result<Self> {
        let mut read_buffer = reader.read_slice_checked(core::mem::size_of::<u16>() * N)?;

        let mut write_buffer: [MaybeUninit<u16>; N] =
            unsafe { MaybeUninit::uninit().assume_init() };
        let read_ptr = &mut read_buffer;

        for elem in write_buffer.iter_mut() {
            elem.write(u16::read_checked(read_ptr)?);
        }

        Ok(unsafe { *write_buffer.as_ptr().cast() })
    }
}
impl<const N: usize> WriteDataChecked for [u16; N] {
    fn write_to_checked(self, writer: &mut impl CheckedWriter) -> Result<()> {
        for v in self.iter() {
            writer.write(*v)?;
        }
        Ok(())
    }
}

impl ReadDataChecked for u8 {
    fn read_checked(reader: &mut impl CheckedReader) -> Result<Self> {
        reader.read_slice_checked(1).map(|m| m[0])
    }
}

impl WriteDataChecked for u8 {
    fn write_to_checked(self, writer: &mut impl CheckedWriter) -> Result<()> {
        writer.write_slice(&[self])
    }
}

macro_rules! impl_read_write_data {
    ($($t:ty),+) => {
        $(
            impl ReadDataChecked for $t {
                #[inline(always)]
                fn read_checked(reader: &mut impl CheckedReader) -> Result<$t> {
                    let data = reader.read_checked();
                    data.map(<$t>::from_be_bytes)
                }
            }

            impl WriteDataChecked for $t {
                #[inline(always)]
                fn write_to_checked(self, writer: &mut impl CheckedWriter) -> Result<()> {
                    let data = self.to_be_bytes();
                    writer.write(data)
                }
            }
         )*
    };
}

impl_read_write_data! {
    u16,
    u32,
    u64
}