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extern crate byteorder;

mod read;
mod write;

pub use self::read::*;
pub use self::write::{CDBWriter};

const ENTRIES: usize = 256;
const PAIR_SIZE: usize = 8;

#[derive(Copy, Clone)]
struct PosLen {
    pos: usize,
    len: usize,
}

impl PosLen {
    fn valid(&self, datalen : u64) -> bool
    {
        (self.pos + self.len) as u64 <= datalen
    }
}

struct CDBHash(u32);

impl CDBHash
{
    fn new(d: &[u8]) -> Self
    {
        let h = d.iter().fold(5381u32, |h, &c| (h << 5).wrapping_add(h) ^ u32::from(c));
        CDBHash(h)
    }

    fn table(&self) -> usize
    {
        self.0 as usize % ENTRIES
    }

    fn slot(&self, tlen: usize) -> usize
    {
        (self.0 as usize >> 8) % tlen
    }
}

impl std::fmt::Debug for CDBHash {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        write!(f, "CDBHash(0x{:08x})", self.0)
    }
}

impl<'a> From<&'a CDBHash> for u32
{
    fn from(h : &'a CDBHash) -> Self
    {
        h.0
    }
}