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Fix merge issues

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This commit is contained in:
Alexander Neuhäuser
2025-12-20 17:31:00 +01:00
parent 3c897673a8
commit 68a78861c0
2 changed files with 0 additions and 217 deletions
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216
src/heap.rs
View File

@@ -1,216 +0,0 @@
#![allow(static_mut_refs)]
use core::{
alloc::GlobalAlloc,
ptr::{self, null_mut, read_volatile},
};
use crate::NovaError;
extern crate alloc;
extern "C" {
static mut __heap_start: u8;
static mut __heap_end: u8;
}
#[repr(C, align(16))]
pub struct HeapHeader {
pub next: *mut HeapHeader,
before: *mut HeapHeader,
pub size: usize,
free: bool,
}
const HEAP_HEADER_SIZE: usize = size_of::<HeapHeader>();
const MIN_BLOCK_SIZE: usize = 16;
// TODO: This implementation has to be reevaluated when implementing multiprocessing
// Spinlock could be a solution but has its issues:
// https://matklad.github.io/2020/01/02/spinlocks-considered-harmful.html
pub static mut HEAP: Heap = Heap {
start_address: &raw mut __heap_start as *mut HeapHeader,
end_address: &raw mut __heap_end as *mut HeapHeader,
raw_size: 0,
};
// TODO: investigate if there is a better alternative to this
pub unsafe fn init_global_heap() {
HEAP.init();
}
#[derive(Default)]
pub struct Novalloc;
unsafe impl GlobalAlloc for Novalloc {
unsafe fn alloc(&self, layout: core::alloc::Layout) -> *mut u8 {
HEAP.malloc(layout.size()).unwrap()
}
unsafe fn dealloc(&self, ptr: *mut u8, _: core::alloc::Layout) {
HEAP.free(ptr).unwrap();
}
}
#[global_allocator]
static GLOBAL_ALLOCATOR: Novalloc = Novalloc;
pub struct Heap {
start_address: *mut HeapHeader,
end_address: *mut HeapHeader,
raw_size: usize,
}
impl Heap {
pub fn new(heap_start: usize, heap_end: usize) -> Self {
let mut instance = Self {
start_address: &raw const heap_start as *mut HeapHeader,
end_address: &raw const heap_end as *mut HeapHeader,
raw_size: heap_end - heap_start,
};
instance.init();
instance
}
fn init(&mut self) {
self.raw_size = self.end_address as usize - self.start_address as usize;
unsafe {
ptr::write(
self.start_address,
HeapHeader {
next: null_mut(),
before: null_mut(),
size: self.raw_size - HEAP_HEADER_SIZE,
free: true,
},
);
}
}
unsafe fn find_first_fit(&self, size: usize) -> Result<*mut HeapHeader, NovaError> {
let mut current = self.start_address;
while !fits(size, current) {
if (*self.start_address).next.is_null() {
return Err(NovaError::HeapFull);
}
current = (*current).next;
}
Ok(current)
}
pub fn malloc(&self, mut size: usize) -> Result<*mut u8, NovaError> {
if size == 0 {
return Err(NovaError::EmptyHeapSegmentNotAllowed);
}
if size < MIN_BLOCK_SIZE {
size = MIN_BLOCK_SIZE;
}
// Align size to the next 16 bytes
size += (16 - (size % 16)) % 16;
unsafe {
// Find First-Fit memory segment
let current = self.find_first_fit(size)?;
// Return entire block WITHOUT generating a new header
// if the current block doesn't have enough space to hold: requested size + HEAP_HEADER_SIZE + MIN_BLOCK_SIZE
if (*current).size < size + HEAP_HEADER_SIZE + MIN_BLOCK_SIZE {
(*current).free = false;
return Ok(current.byte_add(HEAP_HEADER_SIZE) as *mut u8);
}
Self::fragment_segment(current, size);
let data_start_address = current.byte_add(HEAP_HEADER_SIZE);
Ok(data_start_address as *mut u8)
}
}
unsafe fn fragment_segment(current: *mut HeapHeader, size: usize) {
let byte_offset = HEAP_HEADER_SIZE + size;
let new_address = current.byte_add(byte_offset);
// Handle case where fragmenting center free space
let next = (*current).next;
if !(*current).next.is_null() {
(*next).before = new_address;
}
ptr::write(
new_address as *mut HeapHeader,
HeapHeader {
next,
before: current,
size: (*current).size - size - HEAP_HEADER_SIZE,
free: true,
},
);
(*current).next = new_address;
(*current).free = false;
(*current).size = size;
}
pub fn free(&self, pointer: *mut u8) -> Result<(), NovaError> {
let mut segment = unsafe { pointer.sub(HEAP_HEADER_SIZE) as *mut HeapHeader };
unsafe {
// IF prev is free:
// Delete header, add size to previous and fix pointers.
// Move Head left
if !(*segment).before.is_null() && (*(*segment).before).free {
let before_head = (*segment).before;
(*before_head).size += (*segment).size + HEAP_HEADER_SIZE;
delete_header(segment);
segment = before_head;
}
// IF next is free:
// Delete next header and merge size, fix pointers
if !(*segment).next.is_null() && (*(*segment).next).free {
let next_head = (*segment).next;
(*segment).size += (*next_head).size + HEAP_HEADER_SIZE;
delete_header(next_head);
}
// Neither: Set free
(*segment).free = true;
}
Ok(())
}
pub fn traverse_heap(&self) {
let mut pointer_address = self.start_address;
loop {
let head = unsafe { read_volatile(pointer_address) };
println!("Header {:#x}", pointer_address as u32);
println!("free: {}", head.free);
println!("size: {}", head.size);
println!("hasNext: {}", !head.next.is_null());
println!("");
if !head.next.is_null() {
pointer_address = head.next;
} else {
println!("---------------");
return;
}
}
}
}
unsafe fn fits(size: usize, header: *mut HeapHeader) -> bool {
(*header).free && size <= (*header).size
}
unsafe fn delete_header(header: *mut HeapHeader) {
let before = (*header).before;
let next = (*header).next;
if !before.is_null() {
(*before).next = next;
}
if !next.is_null() {
(*next).before = before;
}
}

1
src/lib.rs
View File

@@ -51,7 +51,6 @@ pub mod peripherals;
pub mod configuration; pub mod configuration;
pub mod framebuffer; pub mod framebuffer;
pub mod heap;
pub mod irq_interrupt; pub mod irq_interrupt;
pub mod mailbox; pub mod mailbox;
pub mod timer; pub mod timer;