pub fn pack_u8(value:u8) -> Vec<u8>
{
    vec![value]
}

pub fn unpack_u8(data:&[u8], index:&mut usize) -> u8
{
    let mut result = 0u8;
    if *index < data.len() {
        result = data[*index];
        *index += 1;
    }
    result
}

pub fn pack_u16(value:u16) -> Vec<u8>
{
    vec![(value >> 8) as u8, (value & 0xFF) as u8]
}

pub fn unpack_u16(data:&[u8], index:&mut usize) -> u16
{
    let mut result = 0u16;
    if *index < data.len() {
        result = (data[*index] as u16) << 8;
        *index += 1;
    }
    if *index < data.len() {
        result |= data[*index] as u16;
        *index += 1;
    }
    result
}

pub fn pack_u32(value:u32) -> Vec<u8>
{
    vec![
        (value >> 24) as u8,
        (value >> 16) as u8,
        (value >> 8) as u8,
        (value & 0xFF) as u8,
    ]
}

pub fn unpack_u32(data:&[u8], index:&mut usize) -> u32
{
    let mut result = 0u32;
    for _ in 0..4 {
        result <<= 8;
        if *index < data.len() {
            result |= data[*index] as u32;
            *index += 1;
        } else { break; }
    }
    result
}

pub fn pack_u64(value:u64) -> Vec<u8>
{
    vec![
        (value >> 56) as u8,
        (value >> 48) as u8,
        (value >> 40) as u8,
        (value >> 32) as u8,
        (value >> 24) as u8,
        (value >> 16) as u8,
        (value >> 8) as u8,
        (value & 0xFF) as u8,
    ]
}

pub fn unpack_u64(data:&[u8], index:&mut usize) -> u64
{
    let mut result = 0u64;
    for _ in 0..8 {
        result <<= 8;
        if *index < data.len() {
            result |= data[*index] as u64;
            *index += 1;
        } else { break; }
    }
    result
}