From 4a2445870e892ffd3ed06d1bc818176c832c6fcb Mon Sep 17 00:00:00 2001
From: xqtc161 <xqtc@tutanota.com>
Date: Sun, 23 Jun 2024 02:02:23 +0200
Subject: [PATCH] Implementation of BitVec; Boilerplate for LinkedList

---
 src/main.rs     |  5 ++++
 src/util/mod.rs | 76 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 81 insertions(+)
 create mode 100644 src/util/mod.rs

diff --git a/src/main.rs b/src/main.rs
index ed2eff1..1526af4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,8 @@
 #![no_std]
 #![no_main]
+#![feature(const_mut_refs)]
+#![feature(const_maybe_uninit_write)]
+#![feature(const_maybe_uninit_as_mut_ptr)]
 
 use core::alloc::GlobalAlloc;
 use core::panic::PanicInfo;
@@ -11,9 +14,11 @@ use talc::*;
 
 mod mm;
 mod print;
+mod util;
 
 static mut START_ARENA: [u8; 10000] = [0; 10000];
 
+// temp till mm is ready
 #[global_allocator]
 static ALLOCATOR: Talck<spin::Mutex<()>, ClaimOnOom> =
     Talc::new(unsafe { ClaimOnOom::new(Span::from_const_array(core::ptr::addr_of!(START_ARENA))) })
diff --git a/src/util/mod.rs b/src/util/mod.rs
new file mode 100644
index 0000000..23bd8c8
--- /dev/null
+++ b/src/util/mod.rs
@@ -0,0 +1,76 @@
+use core::mem::{transmute, MaybeUninit};
+use core::ptr::{null_mut, NonNull};
+
+pub struct BitVec {
+    data: NonNull<[u8]>,
+}
+
+impl BitVec {
+    pub fn new(data: NonNull<[u8]>) -> Self {
+        Self { data }
+    }
+
+    pub fn get(&self, index: usize) -> bool {
+        let data = unsafe { self.data.as_ref() };
+        let byte = data[index / u8::BITS as usize];
+        let bit_index = index % u8::BITS as usize;
+        byte & (1 << bit_index) != 0
+    }
+
+    pub fn flip(&mut self, index: usize) -> bool {
+        let data = unsafe { self.data.as_mut() };
+        let byte = &mut data[index / u8::BITS as usize];
+        let bit_index = index % u8::BITS as usize;
+        *byte ^= 1 << bit_index;
+        *byte & (1 << bit_index) != 0
+    }
+}
+
+pub struct LinkedList {
+    prev: NonNull<LinkedList>,
+    next: NonNull<LinkedList>,
+}
+
+impl LinkedList {
+    /// # Safety
+    ///
+    /// THIS DOES NOT ACTUALLY INITIALIZE [`LinkedList`]!
+    /// Call [`LinkedList::init`] to initalize.
+    pub const unsafe fn new() -> Self {
+        let totally_non_null = unsafe { NonNull::new_unchecked(null_mut()) };
+        Self {
+            prev: totally_non_null,
+            next: totally_non_null,
+        }
+    }
+
+    pub const unsafe fn init(this: &mut MaybeUninit<Self>) {
+        let this_ptr = unsafe { NonNull::new_unchecked(this.as_mut_ptr()) };
+        this.write(Self {
+            prev: this_ptr,
+            next: this_ptr,
+        });
+    }
+
+    pub fn insert_after(&mut self, node: NonNull<LinkedList>) {}
+
+    fn prev(&self) -> &Self {
+        unsafe { self.prev.as_ref() }
+    }
+
+    fn next(&self) -> &Self {
+        unsafe { self.next.as_ref() }
+    }
+
+    fn prev_mut(&mut self) -> &mut Self {
+        unsafe { self.prev.as_mut() }
+    }
+
+    fn next_mut(&mut self) -> &mut Self {
+        unsafe { self.next.as_mut() }
+    }
+}
+
+macro_rules! add {
+    () => {};
+}