use crate::board;

pub struct Uart {
    base: usize,
}

impl Uart {
    pub fn new() -> Self {
        Self {
            base: crate::mmu::phys_to_virt(board::UART_BASE),
        }
    }

    pub fn put_char(&self, byte: u8) {
        let ptr = self.base as *mut u8;
        unsafe { core::ptr::write_volatile(ptr, byte) };
    }

    pub fn write_str(&self, s: &str) {
        for byte in s.bytes() {
            self.put_char(byte);
        }
    }

    pub fn write_hex(&self, mut value: usize) {
        self.write_str("0x");
        if value == 0 {
            self.put_char(b'0');
            return;
        }
        let mut buf = [0u8; 16];
        let mut i = 0;
        while value > 0 {
            let digit = (value & 0xF) as u8;
            buf[i] = if digit < 10 {
                b'0' + digit
            } else {
                b'a' + digit - 10
            };
            value >>= 4;
            i += 1;
        }
        while i > 0 {
            i -= 1;
            self.put_char(buf[i]);
        }
    }

    pub fn write_dec(&self, mut value: usize) {
        if value == 0 {
            self.put_char(b'0');
            return;
        }
        let mut buf = [0u8; 20];
        let mut i = 0;
        while value > 0 {
            buf[i] = b'0' + (value % 10) as u8;
            value /= 10;
            i += 1;
        }
        while i > 0 {
            i -= 1;
            self.put_char(buf[i]);
        }
    }
}