lib.rs

const BLOCK_ALIGN: usize = 4; // 32 bits
fn block_body<'a>(len: usize) -> Box<Fn(&'a [u8]) -> IResult<&'a [u8],&'a [u8]>> {
    return Box::new(move |input:&'a [u8]| -> IResult<&'a [u8],&'a [u8]> {
        if input.len() < len {
            Incomplete(Needed::Size(len as u32))
        } else {
            let spill = (BLOCK_ALIGN - (len & 3 )) & 3;
            let consumed: &'a [u8] = &input[len+spill..];
            let parsed: &'a [u8] = &input[0..len];

            Done(consumed, parsed)
        }
    })
}