1 files changed, 183 insertions, 0 deletions
diff --git a/src/util/fifo_queue.rs b/src/util/fifo_queue.rs
new file mode 100644
index 0000000..7ec939b
--- /dev/null
+++ b/src/util/fifo_queue.rs
@@ -0,0 +1,183 @@
+use crate::sync::NullLock;
+use crate::sync::interface::Mutex;
+use crate::vprintln;
+use core::fmt;
+use core::fmt::{Debug,Formatter};
+
+/// # Initialize Queue
+/// - Name: Symbol name
+/// - Size: Number of elements
+/// - Default: Default value
+/// - Type: Data Type
+#[macro_export]
+macro_rules! init_queue {
+	($name:tt,$size:tt,$default:tt,$type:ty) => {
+		init_queue!{@gen [$name,$size,$default,$type,concat!("# ", stringify!($type), " Queue Allocator")]}
+	};
+	(@gen [$name:tt,$size:tt,$default:tt,$type:ty,$doc:expr]) => {
+		#[doc = $doc]
+		#[link_section = ".data.alloc"]
+		pub static $name: QueueAllocator<'static, $type, {$size+2}> = QueueAllocator::<$type, {$size+2}>{inner: NullLock::new([QueueItem::new($default); {$size+2}])};
+	};
+}
+
+#[derive(Copy,Clone)]
+/// # Queue Item
+///
+/// Encapsulates a data element and a pointer to
+/// the next `Queue` item
+pub struct QueueItem<'a, T: Sized> {
+	/// # Data
+	///
+	/// The encapsulated data
+	data: T,
+	/// # Pointer to the next item
+	///
+	/// Stores either `None` or points
+	/// to the next item.
+	next: Option<*mut QueueItem<'a, T>>,
+}
+
+impl<T> QueueItem<'_,T> {
+	/// # Constructor
+	pub const fn new(data: T) -> Self {
+		Self {
+			data: data,
+			next: None,
+		}
+	}
+	/// # Get the inner data
+	///
+	/// Returns a borrow of the underlying data.
+	pub fn inner(&mut self) -> &mut T {
+		&mut self.data
+	}
+	/// # Get pointer to inner data
+	pub fn ptr(&mut self) -> *mut u8 {
+		self.inner() as *mut T as *mut u8
+	}
+}
+
+/// # Sharing Thread Safety for QueueItem
+unsafe impl<T> Send for QueueItem<'_,T> {}
+
+impl<T: Debug> Debug for QueueItem<'_,T> {
+	/// # Debug formatter for `QueueItem`
+	///
+	/// Output the encapsulated data
+	fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+		#[cfg(feature="verbose")]
+		return write!(f, "{:?} {:x} {:?}", self.data, self as *const QueueItem<'_,T> as usize, self.next);
+
+		#[cfg(not(feature="verbose"))]
+		return write!(f, "{:?}", self.data);
+	}
+}
+
+/// # Queue Allocator
+///
+/// Structure to store a pool of allocated data structures.
+pub struct QueueAllocator<'a, T: Sized, const COUNT: usize> {
+	/// # Synchronized Pool of items
+	///
+	/// Stores synchronization wrapper around the data pool
+	pub inner: NullLock<[QueueItem<'a, T>;COUNT]>,
+}
+
+/// # Sharing Thread Safety for QueueAllocator
+unsafe impl<T,const COUNT: usize> Send for QueueAllocator<'_,T,COUNT> {}
+
+impl<'a, T: Sized,const COUNT: usize> QueueAllocator<'a, T, COUNT> {
+	/// # Initialization of Fixed-Size Pool
+	/// 
+	/// Establishes the header and footer of the queue
+	/// as the first and second elements respectively.
+	/// All of the internal elements point to the next
+	/// one and the final element points to `None`
+	pub fn init(&self) {
+		vprintln!("QA: Initializing Queue Allocator!");
+		self.inner.lock(|queue| {
+			vprintln!("QA: Clearing internal references...");
+			for idx in 2..COUNT {
+				if idx != COUNT-1 {
+					queue[idx].next = Some(&mut queue[idx+1] as *mut QueueItem<'a, T>);
+				} else {
+					queue[idx].next = None;
+				}
+			}
+			vprintln!("QA: Initializing head and tail...");
+			queue[0].next = Some(&mut queue[2] as *mut QueueItem<'a, T>);
+			queue[1].next = Some(&mut queue[COUNT-1] as *mut QueueItem<'a, T>);
+		});
+		vprintln!("QA: Initialized Queue Allocator!");
+	}
+
+	/// # Allocate Data
+	///
+	/// If there is a data chunk available,
+	/// return it, otherwise return `None`
+	#[allow(dead_code)]
+	pub fn alloc(&self) -> Option<&mut QueueItem<'a,T>> {
+		vprintln!("QA: Allocating chunk!");
+		return self.inner.lock(|pool| {
+			if let Some(entry) = pool[0].next {
+				vprintln!("QA: Found chunk!");
+				pool[0].next = unsafe { (*entry).next };
+				unsafe {
+					(*entry).next = None;
+				}
+				match pool[0].next {
+					None => {
+						pool[1].next = None
+					}
+					_ => {}
+				}
+				vprintln!("QA: \x1b[92mAllocated {:x}\x1b[0m", unsafe{(*entry).ptr() as usize});
+				return Some(unsafe{&mut *entry as &mut QueueItem<'a,T>});
+			} else {
+				vprintln!("QA: No chunks available!");
+				return None;
+			}
+		});
+	}
+
+	/// # Free
+	///
+	/// Add the item to the end of the queue.
+	/// If there were no items, set it as the head.
+	#[allow(dead_code)]
+	pub fn free(&self, freed_item: &mut QueueItem<'a,T>) {
+		vprintln!("QA: Deallocating chunk!");
+		self.inner.lock(|pool| {
+			freed_item.next = None;
+			match pool[1].next {
+				None => {
+					pool[0].next = Some(freed_item as *mut QueueItem<'a,T>);
+				}
+				Some(entry) => {
+					unsafe {
+						(*entry).next = Some(freed_item as *mut QueueItem<'a,T>);
+					}
+				}
+			}
+			pool[1].next = Some(freed_item as *mut QueueItem<'a,T>);
+			vprintln!("QA: \x1b[91mDeallocated {:x}\x1b[0m", freed_item.ptr() as usize);
+		});
+	}
+}
+
+impl<T: Debug,const COUNT: usize> Debug for QueueAllocator<'_,T,COUNT> {
+	/// # Debug Formatted Output
+	///
+	/// Output each data point in the array with
+	/// its debug formatter.
+	fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+		self.inner.lock(|queue| {
+			#[cfg(feature="verbose")]
+			return write!(f, "{:?}", queue);
+
+			#[cfg(not(feature="verbose"))]
+			return write!(f, "{:?}", queue);
+		})
+	}
+}