path: root/src/mem/alloc.rs

//! # Allocate crate
//!
//! Provides the Global allocator and methods
//! to create special purpose allocators.
use alloc::alloc::{GlobalAlloc,Layout};
use crate::sync::NullLock;
use crate::sync::interface::Mutex;
use core::fmt::{Debug,Formatter,Result};

/// # Initialize Queue
/// - Name: Symbol name
/// - Size: Number of elements
/// - Default: Default value
/// - Type: Data Type
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{data: $default, next: None}; {$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> {
	/// # 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<'_>) -> Result {
		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) {
		self.inner.lock(|queue| {
			for idx in 2..queue.len() {
				if idx != queue.len()-1 {
					queue[idx].next = Some(&mut queue[idx+1] as *mut QueueItem<'_, T>);
				} else {
					queue[idx].next = None;
				}
			}
			queue[0].next = Some(&mut queue[2] as *mut QueueItem<'_, T>);
			queue[1].next = Some(&mut queue[queue.len()-1] as *mut QueueItem<'_, T>);
		});
	}

	/// # 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>> {
		return self.inner.lock(|pool| {
			if let Some(entry) = pool[0].next {
				pool[0].next = unsafe { (*entry).next };
				unsafe {
					(*entry).next = None;
				}
				match pool[0].next {
					None => {
						pool[1].next = None
					}
					_ => {}
				}
				return Some(unsafe{&mut *entry as &mut QueueItem<'a,T>});
			} else {
				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>) {
		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>);
		});
	}
}

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<'_>) -> Result {
		self.inner.lock(|queue| {
			write!(f, "{:?}", queue)
		})
	}
}





/// # u256 struct
///
/// 256 bit size field
#[derive(Copy,Clone)]
pub struct U256(u128,u128);

/// # Grand Allocator
///
/// The structure that uses different sized pools and allocates memory chunks
pub struct GrandAllocator { }

/// # The number of elements of each size
const GRAND_ALLOC_SIZE: usize = 64;

init_queue!(U8_GRAND_ALLOC, GRAND_ALLOC_SIZE, 0, u8);
init_queue!(U16_GRAND_ALLOC, GRAND_ALLOC_SIZE, 0, u16);
init_queue!(U32_GRAND_ALLOC, GRAND_ALLOC_SIZE, 0, u32);
init_queue!(U64_GRAND_ALLOC, GRAND_ALLOC_SIZE, 0, u64);
init_queue!(U128_GRAND_ALLOC, GRAND_ALLOC_SIZE, 0, u128);
init_queue!(U256_GRAND_ALLOC, GRAND_ALLOC_SIZE, {U256(0,0)}, U256);

impl GrandAllocator {
	pub fn init(&self) {
		U8_GRAND_ALLOC.init();
		U16_GRAND_ALLOC.init();
		U32_GRAND_ALLOC.init();
		U64_GRAND_ALLOC.init();
		U128_GRAND_ALLOC.init();
		U256_GRAND_ALLOC.init();
	}
}

unsafe impl GlobalAlloc for GrandAllocator {
	/// # Allocator
	///
	/// Allocate the fixed size chunks
	unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
		match layout.size() {
			1 => {
				match U8_GRAND_ALLOC.alloc() {
					None => {
						panic!("No cells to allocate!");
					}
					Some(elem) => {
						return (*elem).ptr();
					}
				}
			}
			2 => {
				match U16_GRAND_ALLOC.alloc() {
					None => {
						panic!("No cells to allocate!");
					}
					Some(elem) => {
						return (*elem).ptr();
					}
				}
			}
			3..=4 => {
				match U32_GRAND_ALLOC.alloc() {
					None => {
						panic!("No cells to allocate!");
					}
					Some(elem) => {
						return (*elem).ptr();
					}
				}
			}
			5..=8 => {
				match U64_GRAND_ALLOC.alloc() {
					None => {
						panic!("No cells to allocate!");
					}
					Some(elem) => {
						return (*elem).ptr();
					}
				}
			}
			9..=16 => {
				match U128_GRAND_ALLOC.alloc() {
					None => {
						panic!("No cells to allocate!");
					}
					Some(elem) => {
						return (*elem).ptr();
					}
				}
			}
			17..=32 => {
				match U256_GRAND_ALLOC.alloc() {
					None => {
						panic!("No cells to allocate!");
					}
					Some(elem) => {
						return (*elem).ptr();
					}
				}
			}
			_ => {
				panic!("No allocators for size {}!", layout.size());
			}
		}
	}

	/// # Deallocate
	///
	/// Deallocate the fixed size chunks by searching for them
	unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
		match layout.size() {
			1 => {
				U8_GRAND_ALLOC.inner.lock(|pool| {
					let spacing: usize = (pool[3].ptr() as usize) - (pool[2].ptr() as usize);
					let diff: usize = (ptr as usize) - (pool[2].ptr() as usize);
					let index: usize = diff/spacing;
					assert!(index < GRAND_ALLOC_SIZE, "{} is out of the allocation bounds ({})", index, GRAND_ALLOC_SIZE);
					assert_eq!(diff % spacing, 0, "{} is not aligned with the spacings and so it must not have been allocated by the Grand Allocator", diff % spacing);
					U8_GRAND_ALLOC.free(&mut pool[index]);
				});
			}
			2 => {
				U16_GRAND_ALLOC.inner.lock(|pool| {
					let spacing: usize = (pool[3].ptr() as usize) - (pool[2].ptr() as usize);
					let diff: usize = (ptr as usize) - (pool[2].ptr() as usize);
					let index: usize = diff/spacing;
					assert!(index < GRAND_ALLOC_SIZE, "{} is out of the allocation bounds ({})", index, GRAND_ALLOC_SIZE);
					assert_eq!(diff % spacing, 0, "{} is not aligned with the spacings and so it must not have been allocated by the Grand Allocator", diff % spacing);
					U16_GRAND_ALLOC.free(&mut pool[index]);
				});
			}
			3..=4 => {
				U32_GRAND_ALLOC.inner.lock(|pool| {
					let spacing: usize = (pool[3].ptr() as usize) - (pool[2].ptr() as usize);
					let diff: usize = (ptr as usize) - (pool[2].ptr() as usize);
					let index: usize = diff/spacing;
					assert!(index < GRAND_ALLOC_SIZE, "{} is out of the allocation bounds ({})", index, GRAND_ALLOC_SIZE);
					assert_eq!(diff % spacing, 0, "{} is not aligned with the spacings and so it must not have been allocated by the Grand Allocator", diff % spacing);
					U32_GRAND_ALLOC.free(&mut pool[index]);
				});
			}
			5..=8 => {
				U64_GRAND_ALLOC.inner.lock(|pool| {
					let spacing: usize = (pool[3].ptr() as usize) - (pool[2].ptr() as usize);
					let diff: usize = (ptr as usize) - (pool[2].ptr() as usize);
					let index: usize = diff/spacing;
					assert!(index < GRAND_ALLOC_SIZE, "{} is out of the allocation bounds ({})", index, GRAND_ALLOC_SIZE);
					assert_eq!(diff % spacing, 0, "{} is not aligned with the spacings and so it must not have been allocated by the Grand Allocator", diff % spacing);
					U64_GRAND_ALLOC.free(&mut pool[index]);
				});
			}
			9..=16 => {
				U128_GRAND_ALLOC.inner.lock(|pool| {
					let spacing: usize = (pool[3].ptr() as usize) - (pool[2].ptr() as usize);
					let diff: usize = (ptr as usize) - (pool[2].ptr() as usize);
					let index: usize = diff/spacing;
					assert!(index < GRAND_ALLOC_SIZE, "{} is out of the allocation bounds ({})", index, GRAND_ALLOC_SIZE);
					assert_eq!(diff % spacing, 0, "{} is not aligned with the spacings and so it must not have been allocated by the Grand Allocator", diff % spacing);
					U128_GRAND_ALLOC.free(&mut pool[index]);
				});
			}
			17..=32 => {
				U256_GRAND_ALLOC.inner.lock(|pool| {
					let spacing: usize = (pool[3].ptr() as usize) - (pool[2].ptr() as usize);
					let diff: usize = (ptr as usize) - (pool[2].ptr() as usize);
					let index: usize = diff/spacing;
					assert!(index < GRAND_ALLOC_SIZE, "{} is out of the allocation bounds ({})", index, GRAND_ALLOC_SIZE);
					assert_eq!(diff % spacing, 0, "{} is not aligned with the spacings and so it must not have been allocated by the Grand Allocator", diff % spacing);
					U256_GRAND_ALLOC.free(&mut pool[index]);
				});
			}
			_ => {
				panic!("No deallocators for size {}!", layout.size());
			}
		}
	}
}

/// # Grand Allocator
///
/// The allocator of allocators. It hands out fixed sized memory chunks.
#[global_allocator]
pub static ALLOCATOR: GrandAllocator = GrandAllocator{};