BitWrap

BitWrap is a derive macro and trait to declare a struct data member with explicit size, in bits.

BitWrap Trait

BitWrap trait declares 2 methods:

fn pack(&self, dst: &mut [u8]) -> Result<usize, BitWrapError>

pack method serialize struct fields into dst array

fn unpack(&mut self, src: &[u8]) -> Result<usize, BitWrapError>

unpack method deserialize struct fields from src array

BitWrap Macro

use bitwrap::BitWrap;

#[derive(BitWrap)]
struct Packet {
    // Get/Set bit
    #[bits(1)]
    flag_1: u8,

    // Get/Set bit and convert into bool (0 - false, 1 - true)
    #[bits(1)]
    flag_2: bool,

    // Fixed 6 bits
    // on 'pack()' set 6 bits to value in the skip option
    // on 'unpack()' skip 6 bits
    #[bits(6, skip = 0b111111)]

    // Get 8 bits and convert them to Enum
    // on 'pack()' call 'into(Enum) -> T'
    // on 'unpack()' call 'from(T) -> Enum'
    // T is a unsigned number depend of the bit field size
    #[bits(8, from = Enum::from, into = Enum::into)]
    variant: Enum,

    // call BitWrap methods for Ipv4Addr
    #[bits]
    ip: std::net::Ipv4Addr

    // set_len returns self.data.len()
    #[bits(8, into = self.set_len)]
    len: usize,

    // call BitWrap method for Vec<T> with defined buffer length
    // where T is u8 or with implemented BitWrap + Default traits
    #[bytes(self.len)]
    data: Vec<u8>,
}