riscv-rt 0.17.1

Minimal runtime / startup for RISC-V CPU's
Documentation 
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#![no_std]
#![no_main]

extern crate panic_halt;

use riscv::asm::wfi;
use riscv::register::{mie, mip};
use riscv_rt::entry;

#[export_name = "_mp_hook"]
#[rustfmt::skip]
pub extern "Rust" fn user_mp_hook(hartid: usize) -> bool {
    if hartid == 0 {
        true
    } else {
        let addr = 0x02000000 + hartid * 4;
        unsafe {
            // Clear IPI
            (addr as *mut u32).write_volatile(0);

            // Start listening for software interrupts
            mie::set_msoft();

            loop {
                wfi();
                if mip::read().msoft() {
                    break;
                }
            }

            // Stop listening for software interrupts
            mie::clear_msoft();

            // Clear IPI
            (addr as *mut u32).write_volatile(0);
        }
        false
    }
}

#[entry]
fn main(hartid: usize) -> ! {
    if hartid == 0 {
        // Waking hart 1...
        let addr = 0x02000004;
        unsafe {
            (addr as *mut u32).write_volatile(1);
        }
    }

    loop {}
}