Function read_byte_array_sign_extending

fn read_byte_array_sign_extending<const N: usize, const FILL: u8>(
    data: &mut &[u8],
    length: usize,
) -> [u8; N]

Read length bytes from data at offset, updating the latter. Extend the resulting buffer to an array of N bytes by inserting FILL in the k most significant bytes, where k = N - length.

SAFETY:

• length <= N
• offset + length <= data.len()