1 files changed, 92 insertions, 0 deletions
diff --git a/src/alloc.rs b/src/alloc.rs
new file mode 100644
index 0000000..4fe44ee
--- /dev/null
+++ b/src/alloc.rs
@@ -0,0 +1,92 @@
+use crate::sync::NullLock;
+use crate::sync::interface::Mutex;
+
+const CHAR_COUNT: usize = 20;
+const CHAR_POOL_SIZE: usize = CHAR_COUNT + 2;
+
+#[derive(Copy,Clone)]
+pub struct CharCell {
+	pub data: char,
+	next: Option<*mut CharCell>,
+}
+
+impl CharCell {
+	pub const fn new() -> Self {
+		Self {
+			data: '\0',
+			next: None,
+		}
+	}
+}
+
+use core::fmt::{Debug,Formatter,Result};
+impl Debug for CharCell {
+	fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+		write!(f, "{}", self.data)
+	}
+}
+
+unsafe impl Send for CharCell {}
+
+pub struct CharAllocator(NullLock<[CharCell; CHAR_POOL_SIZE]>);
+
+impl CharAllocator {
+	pub const fn new() -> Self {
+		Self(NullLock::new([CharCell::new(); CHAR_POOL_SIZE]))
+	}
+
+	pub fn init(&self) {
+		self.0.lock(|char_pool| {
+			for idx in 2..CHAR_POOL_SIZE {
+				if idx != CHAR_POOL_SIZE - 1 {
+					char_pool[idx].next = Some(&mut char_pool[idx+1] as *mut CharCell);
+				} else {
+					char_pool[idx].next = None;
+				}
+			}
+			char_pool[0].next = Some(&mut char_pool[2] as *mut CharCell);
+			char_pool[1].next = Some(&mut char_pool[CHAR_POOL_SIZE-1] as *mut CharCell);
+		});
+	}
+
+	pub fn alloc(&self) -> Option<&mut CharCell> {
+		return self.0.lock(|char_pool| {
+			if let Some(char_cell) = char_pool[0].next {
+				char_pool[0].next = unsafe{(*char_cell).next};
+				unsafe {
+					(*char_cell).next = None;
+				}
+				return Some(unsafe{&mut *char_cell as &mut CharCell});
+			} else {
+				return None;
+			}
+		});
+	}
+
+	pub fn free(&self, cell: &mut CharCell) {
+		self.0.lock(|char_pool| {
+			cell.next = None;
+			match char_pool[1].next {
+				None => {
+					char_pool[0].next = Some(cell as *mut CharCell);
+				}
+				Some(ocell) => {
+					unsafe {
+						(*ocell).next = Some(cell as *mut CharCell);
+					}
+				}
+			}
+			char_pool[1].next = Some(cell as *mut CharCell);
+		});
+	}
+}
+
+impl Debug for CharAllocator {
+	fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+		self.0.lock(|pool| {
+			write!(f, "{:?}", pool)
+		})
+	}
+}
+
+pub static CHAR_ALLOCATOR: CharAllocator = CharAllocator::new();