#![no_std]
#![no_main]

use core::fmt::Write;
use core::str::from_utf8;

use cortex_m_rt::entry;
use defmt::*;
use embassy_executor::Executor;
use embassy_stm32::mode::Async;
use embassy_stm32::spi;
use embassy_stm32::time::mhz;
use heapless::String;
use static_cell::StaticCell;
use {defmt_rtt as _, panic_probe as _};

#[embassy_executor::task]
async fn main_task(mut spi: spi::Spi<'static, Async, spi::mode::Master>) {
    for n in 0u32.. {
        let mut write: String<128> = String::new();
        let mut read = [0; 128];
        core::write!(&mut write, "Hello DMA World {}!\r\n", n).unwrap();
        // transfer will slice the &mut read down to &write's actual length.
        spi.transfer(&mut read, write.as_bytes()).await.ok();
        info!("read via spi+dma: {}", from_utf8(&read).unwrap());
    }
}

static EXECUTOR: StaticCell<Executor> = StaticCell::new();

#[entry]
fn main() -> ! {
    info!("Hello World!");
    let p = embassy_stm32::init(Default::default());

    let mut spi_config = spi::Config::default();
    spi_config.frequency = mhz(1);

    let spi = spi::Spi::new(p.SPI3, p.PB3, p.PB5, p.PB4, p.GPDMA1_CH0, p.GPDMA1_CH1, spi_config);

    let executor = EXECUTOR.init(Executor::new());

    executor.run(|spawner| {
        spawner.spawn(unwrap!(main_task(spi)));
    })
}
