pub struct Stack {
    pub mem: [u8; 256],
    pub sp: u8,
}

impl Stack {
    pub fn new() -> Self {
        Self {
            mem: [0; 256],
            sp: 0,
        }
    }

    pub fn push_u8(&mut self, val: u8) {
        self.mem[self.sp as usize] = val;
        self.sp = self.sp.wrapping_add(1);
    }

    pub fn pop_u8(&mut self) -> u8 {
        self.sp = self.sp.wrapping_sub(1);
        self.mem[self.sp as usize]
    }

    pub fn push_u16(&mut self, val: u16) {
        let [byte_high, byte_low] = u16::to_be_bytes(val);
        self.push_u8(byte_high);
        self.push_u8(byte_low);
    }

    pub fn pop_u16(&mut self) -> u16 {
        let byte_low = self.pop_u8();
        let byte_high = self.pop_u8();
        u16::from_be_bytes([byte_high, byte_low])
    }

    pub fn reset(&mut self) {
        self.mem.fill(0);
        self.sp = 0;
    }
}