Function read_vlq

blobby/src/decode.rs:3–42

(data: &mut &[u8])

use super::{Error, NEXT_MASK, VAL_MASK};

pub(crate) const fn read_vlq(data: &mut &[u8]) -> Result<usize, Error> {
    let b = match data.split_first() {
        Some((&b, rest)) => {
            *data = rest;
            b
        }
        None => return Err(Error::UnexpectedEnd),
    };
    let mut next = b & NEXT_MASK;
    let mut val = (b & VAL_MASK) as usize;

    macro_rules! step {
        () => {
            if next == 0 {
                return Ok(val);
            }
            let b = match data.split_first() {
                Some((&b, rest)) => {
                    *data = rest;
                    b
                }
                None => return Err(Error::UnexpectedEnd),
            };

            next = b & NEXT_MASK;
            let t = (b & VAL_MASK) as usize;
            val = ((val + 1) << 7) + t;
        };
    }

    step!();
    step!();
    step!();

    if next != 0 {
        return Err(Error::InvalidVlq);
    }

    Ok(val)
}

macro_rules! try_read_vlq {
    ($data:expr) => {