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#![feature(naked_functions)]
#![no_std]
#![no_main]
use core::arch::asm;
use gd32vf103_pac::Peripherals;
#[no_mangle]
fn main(_hartid: usize) -> ! {
// let peripherals = Peripherals::take().unwrap();
let peripherals = unsafe { Peripherals::steal() };
let rcu = peripherals.RCU;
// enable RCU_GPIOA
rcu.apb2en.write(|w| {
w.paen().set_bit()
});
let gpio = peripherals.GPIOA;
// led is gpioa pin 7 output push/pull 50mhz
gpio.ctl0.write(|w| unsafe {
// output mode, push-pull
w.ctl7().bits(0b00);
// 50 mhz output rate
w.md7().bits(0b11);
w
});
let mut led_on = false;
loop {
if led_on {
gpio.bc.write(|w| w.cr7().set_bit());
if gpio.octl.read().octl7().bit() {
panic!("not set");
}
} else {
gpio.bop.write(|w| w.bop7().set_bit());
if !gpio.octl.read().octl7().bit() {
panic!("set");
}
}
led_on = !led_on;
let mut a = 0;
for _ in 1..100_000 {
a = gpio.octl.read().bits();
}
}
}
#[naked]
#[link_section = ".text.init"]
#[export_name = "_start"]
unsafe extern "C" fn _start() -> ! {
// At boot, the hart is in privilege mode M, mstatus fields MIE
// and MPRV are 0, the pc is set to a reset vector, the mcause
// register specifies why the reset occurred.
// c.f.: [^super::rism2] § 3.4 (Reset)
asm!(
".option push",
".option norelax",
"la gp, __global_pointer$",
".option pop",
"csrr a0, mhartid",
"la sp, _stack_top",
"tail main",
options(noreturn)
)
}
#[panic_handler]
fn panic(info: &core::panic::PanicInfo) -> ! {
if let Some(loc) = info.location() {
let _file = loc.file();
let _line = loc.line();
if let Some(_msg) = info.payload().downcast_ref::<&str>() {
loop {}
}
loop {}
}
loop {}
}
|
