use num::PrimInt;

const b_m16_interleave: [u8; 8] = [0, 49, 49, 41, 90, 27, 117, 10];

pub fn sin8(theta: u8) -> u8 {
    let mut offset: u8 = theta;
    if theta & 0x40 != 0 {
        offset = 255 - offset;
    }
    offset &= 0x3f;

    let mut secoffset: u8 = offset & 0x0f;
    if theta & 0x40 != 0 {
        secoffset += 1;
    }

    let section: u8 = offset.unsigned_shr(4);
    let s2: u8 = section * 2;
    let b: u8 = b_m16_interleave[s2 as usize];
    let m16: u8 = b_m16_interleave[s2 as usize + 1];
    let mx: u8 = m16.wrapping_mul(secoffset).unsigned_shr(4);
    let mut y: i8 = mx as i8 + b as i8;
    if theta & 0x80 != 0 {
        y = -y;
    }
    y = y.wrapping_add(128u8 as i8);
    return y as u8;
}

pub fn cos8(theta: u8) -> u8 {
    sin8(theta.wrapping_add(64))
}