`const` function for parsing a 20 byte string into an `Address`. Can be used to declare global variables to hold addresses.

address.rs

pub const fn parse_hex_20b(input: &str) -> [u8; 20] {
    let mut addr = [0; 20];
    let mut i = 0usize;
    let mut idx = 0usize;
    let bytes = input.as_bytes();

    loop {
        let char1 = bytes[i];
        let char2 = bytes[i + 1];
        let mut buf = 0u8;

        match char1 {
            b'A'..=b'F' => buf |= char1 - b'A' + 10,
            b'a'..=b'f' => buf |= char1 - b'a' + 10,
            b'0'..=b'9' => buf |= char1 - b'0',
            _ => panic!("invalid hex character"),
        }
        buf <<= 4;

        match char2 {
            b'A'..=b'F' => buf |= char2 - b'A' + 10,
            b'a'..=b'f' => buf |= char2 - b'a' + 10,
            b'0'..=b'9' => buf |= char2 - b'0',
            _ => panic!("invalid hex character"),
        }

        i += 2;

        addr[idx] = buf;
        idx += 1;

        if i == input.len() {
            break;
        }
    }

    addr
}

pub const fn parse_address(hex: &str) -> H160 {
    let bytes = parse_hex_20b(hex);
    H160(bytes)
}