reduce hardware dependent code

Author: stlankes

src/arch/x86/kernel/processor.rs

@@ -33,45 +33,6 @@ pub(crate) fn mb() {
 	}
 }
 
-/// Search the most significant bit
-#[inline(always)]
-pub(crate) fn msb(value: usize) -> Option<usize> {
-	if value > 0 {
-		let ret: usize;
-
-		unsafe {
-			asm!("bsr {0}, {1}",
-				out(reg) ret,
-				in(reg) value,
-				options(nomem, nostack)
-			);
-		}
-		Some(ret)
-	} else {
-		None
-	}
-}
-
-/// Search the least significant bit
-#[allow(dead_code)]
-#[inline(always)]
-pub(crate) fn lsb(value: usize) -> Option<usize> {
-	if value > 0 {
-		let ret: usize;
-
-		unsafe {
-			asm!("bsf {0}, {1}",
-				out(reg) ret,
-				in(reg) value,
-				options(nomem, nostack)
-			);
-		}
-		Some(ret)
-	} else {
-		None
-	}
-}
-
 #[allow(dead_code)]
 #[inline(always)]
 pub(crate) fn halt() {
@@ -80,13 +41,6 @@ pub(crate) fn halt() {
 	}
 }
 
-#[inline(always)]
-pub(crate) fn pause() {
-	unsafe {
-		asm!("pause", options(nomem, nostack));
-	}
-}
-
 #[allow(unused_variables)]
 #[no_mangle]
 pub(crate) extern "C" fn shutdown(error_code: i32) -> ! {

src/lib.rs

@@ -1,6 +1,7 @@
 #![feature(abi_x86_interrupt)]
 #![feature(alloc_error_handler)]
 #![feature(const_trait_impl)]
+#![feature(int_lowest_highest_one)]
 #![allow(clippy::module_inception)]
 #![allow(static_mut_refs)]
 #![no_std]

src/scheduler/task.rs

@@ -1,5 +1,4 @@
 use crate::arch::mm::VirtAddr;
-use crate::arch::processor::msb;
 use crate::consts::*;
 use alloc::boxed::Box;
 use alloc::collections::VecDeque;
@@ -100,16 +99,17 @@ impl PriorityTaskQueue {
 
 	/// Pop the task with the highest priority from the queue
 	pub fn pop(&mut self) -> Option<Rc<RefCell<Task>>> {
-		if let Some(i) = msb(self.prio_bitmap) {
-			return self.pop_from_queue(i);
+		if let Some(i) = self.prio_bitmap.highest_one() {
+			return self.pop_from_queue(i.try_into().unwrap());
 		}
 
 		None
 	}
 
 	/// Pop the next task, which has a higher or the same priority as `prio`
 	pub fn pop_with_prio(&mut self, prio: TaskPriority) -> Option<Rc<RefCell<Task>>> {
-		if let Some(i) = msb(self.prio_bitmap) {
+		if let Some(i) = self.prio_bitmap.highest_one() {
+			let i: usize = i.try_into().unwrap();
 			if i >= prio.into().into() {
 				return self.pop_from_queue(i);
 			}

src/synch/spinlock.rs

@@ -24,7 +24,7 @@ unsafe impl RawMutex for RawSpinlock {
 	fn lock(&self) {
 		let ticket = self.queue.fetch_add(1, Ordering::Relaxed);
 		while self.dequeue.load(Ordering::Acquire) != ticket {
-			arch::processor::pause();
+			core::hint::spin_loop();
 		}
 	}
 
@@ -107,7 +107,7 @@ unsafe impl RawMutex for RawSpinlockIrqSave {
 
 		while self.dequeue.load(Ordering::Acquire) != ticket {
 			arch::irq::irq_nested_enable(irq);
-			arch::processor::pause();
+			core::hint::spin_loop();
 			arch::irq::irq_nested_disable();
 		}