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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)
})
}
}
#[link_section = ".data.alloc"]
pub static CHAR_ALLOCATOR: CharAllocator = CharAllocator::new();
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