Node / public / precursor-lxmfchat.git / files / xous-core / kernel / src / arch / arm / mod.rs

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// SPDX-FileCopyrightText: 2022 Foundation Devices, Inc <hello@foundationdevices.com>

// SPDX-License-Identifier: Apache-2.0

pub mod exception;

pub mod irq;

pub mod mem;

pub mod panic;

pub mod process;

pub mod syscall;

use core::arch::asm;

use core::num::NonZeroU8;

pub use process::Thread;

use xous_kernel::PID;

pub fn current_pid() -> PID {

let mut current_pid: usize;

unsafe {

asm!(

"mrc p15, 0, {contextidr}, c13, c0, 1",

contextidr = out(reg) current_pid,

);

assert_ne!(current_pid, 0, "Hardware PID is zero");

NonZeroU8::new_unchecked((current_pid & 0xff) as u8)

}

}

pub fn init() {

unsafe {

let pid = 1;

let contextidr = (pid << 8) | pid;

// Set initial (kernel) CONTEXTIDR

asm!(

"mcr p15, 0, {contextidr}, c13, c0, 1",

contextidr = in(reg) contextidr,

);

}

}

pub fn idle() -> bool {

// Ensure data and instruction reads are finished before WFI.

// A NOP instruction after WFI is where an IRQ handler will jump back to

unsafe { asm!("isb", "dsb", "wfi", "nop") }

true

}