#![allow(unsafe_code)]

use cortex_m::singleton;
use stm32f1xx_hal::{afio, dma, gpio, pac, prelude::*, rcc, serial};

pub struct DMX {
    tx: Option<dma::TxDma<serial::Tx<pac::USART1>, dma::dma1::C4>>,
    txbuffer: Option<&'static mut [u8; 512]>,
}

impl DMX {
    pub fn new(
        usart: pac::USART1,
        pins: (
            gpio::Pin<'A', 9, gpio::Alternate<gpio::OpenDrain>>,
            gpio::Pin<'A', 10>,
        ),
        mapr: &mut afio::MAPR,
        channel: dma::dma1::C4,
        clocks: &rcc::Clocks,
    ) -> Self {
        // Serial config
        let serial = serial::Serial::new(usart, pins, mapr, 250_000.bps(), &clocks);

        Self {
            tx: Some(serial.tx.with_dma(channel)),
            txbuffer: None,
        }
    }

    pub fn send(&mut self, data: &[u8; 512]) {
        if let Some(mut tx) = self.tx.take() {
            let mut txbuffer = match self.txbuffer.take() {
                Some(buf) => buf,
                None => singleton!(: [u8; 512] = [0; 512]).unwrap(),
            };

            txbuffer.copy_from_slice(data);
            let xfer = tx.write(txbuffer);

            (txbuffer, tx) = xfer.wait();
            self.tx.replace(tx);
            self.txbuffer.replace(txbuffer);
        }
    }
}