1 files changed, 195 insertions, 0 deletions
diff --git a/Source/Kernel/MemoryManager/Heap.class.cpp b/Source/Kernel/MemoryManager/Heap.class.cpp
new file mode 100644
index 0000000..f5bbe0a
--- /dev/null
+++ b/Source/Kernel/MemoryManager/Heap.class.cpp
@@ -0,0 +1,195 @@
+#include "Heap.class.h"
+#include <MemoryManager/PageDirectory.class.h>
+
+Heap::Heap() {
+	m_usable = false;
+	m_index.data = 0;
+	m_index.size = 0;
+}
+
+Heap::~Heap() {
+	//TODO (optionnal) : free pages.
+}
+
+void Heap::create(u32int start, u32int size, u32int idxsize, PageDirectory* pagedir, bool user, bool rw) {
+	if (start & 0x0FFF) start = (start & 0xFFFFF000) + 0x1000;
+	if (size & 0x0FFF) size = (size & 0xFFFFF000) + 0x1000;
+	m_start = start + idxsize;	//m_start is start of real data, start is start of index.
+	m_end = start + size;
+
+	m_pagedir = pagedir;
+	m_user = user;
+	m_rw = rw;
+	
+	//Allocate frames for heap
+	for (u32int i = start ; i < m_end; i += 0x1000) {
+		m_pagedir->allocFrame(i, m_user, m_rw);
+	}
+
+	m_index.data = (heap_header_t **)start;		//Set index start. start == start of all heap
+	m_index.size = 0;
+
+	heap_header_t *hole = (heap_header_t*) m_start;	//m_start == start of data
+	hole->size = (m_end - m_start);
+	hole->magic = HEAP_MAGIC;
+	hole->is_hole = true;
+
+	heap_footer_t *hole_footer = (heap_footer_t*) (m_end - sizeof(heap_footer_t));
+	hole_footer->header = hole;
+	hole_footer->magic = HEAP_MAGIC;
+
+	insertIntoIndex(hole);
+
+	m_usable = true;
+	m_free = (m_end - m_start);
+}
+
+void Heap::expand(u32int quantity) {
+	if (quantity & 0x00000FFF)
+		quantity = (quantity & 0xFFFFF000) + 0x1000;
+
+	u32int newEnd = m_end + quantity;
+
+	for (u32int i = m_end; i < newEnd; i++) {
+		m_pagedir->allocFrame(i, m_user, m_rw);
+	}
+
+	heap_footer_t *last_footer = (heap_footer_t*) (m_end - sizeof(heap_footer_t));
+	heap_header_t *last_header = last_footer->header;
+	if (last_header->is_hole) {	//Last block of heap is a hole, update its size
+		removeFromIndex(last_header);
+		last_header->size += quantity;
+
+		last_footer = (heap_footer_t*) (newEnd - sizeof(heap_footer_t));
+
+		last_footer->magic = HEAP_MAGIC;
+		last_footer->header = last_header;
+
+		insertIntoIndex(last_header);
+	} else {		//Last block is not a hole. Just add a new hole at the end
+		last_header = (heap_header_t*)m_end;
+		last_footer = (heap_footer_t*) (newEnd - sizeof(heap_footer_t));
+
+		last_header->is_hole = true;
+		last_header->magic = HEAP_MAGIC;
+		last_header->size = quantity;
+		
+		last_footer->magic = HEAP_MAGIC;
+		last_footer->header = last_header;
+
+		insertIntoIndex(last_header);
+	}
+
+	m_end = newEnd;
+	m_free += quantity;
+}
+
+void Heap::contract() {	//Automatically work out how much we can contract
+	heap_footer_t *last_footer = (heap_footer_t*) (m_end - sizeof(heap_footer_t));
+	heap_header_t *last_header = last_footer->header;
+	if (last_header->is_hole == false) return;	//We need a hole at end of heap
+
+	u32int quantity = 0;
+	while ((m_end - m_start) - quantity > HEAP_MIN_SIZE and 
+			(last_header->size - quantity) > 0x1000)	//Always keep at least 0x1000 free at end
+		quantity += 0x1000;
+	if (quantity == 0) return;
+
+	u32int newEnd = m_end - quantity;
+	m_free -= quantity;
+
+	removeFromIndex(last_header);
+	last_header->size -= quantity;
+	last_footer = (heap_footer_t*)((u32int)last_footer - quantity);
+	last_footer->magic = HEAP_MAGIC;
+	last_footer->header = last_header;
+	insertIntoIndex(last_header);
+
+	for (u32int i = newEnd; i < m_end; i += 0x1000) {
+		m_pagedir->freeFrame(i);
+	}
+
+	m_end = newEnd;
+}
+
+void *Heap::alloc(u32int sz, bool no_expand) {
+	u32int newsize = sz + sizeof(heap_header_t) + sizeof(heap_footer_t);
+	u32int iterator = 0;
+	while (iterator < m_index.size) {
+		if (m_index.data[iterator]->size >= newsize) break;
+		iterator++;
+	}
+	if (iterator == m_index.size) { //No hole is big enough
+		if (no_expand) return 0;
+		expand((sz & 0xFFFFF000) + 0x1000);
+		return alloc(sz, true);	//Recurse call
+	}
+
+	heap_header_t *loc = m_index.data[iterator];
+	heap_footer_t *footer = (heap_footer_t*)((u32int)loc + loc->size - sizeof(heap_footer_t));
+	loc->is_hole = false;	//Update current header
+
+	removeFromIndex(loc);
+
+		//Here we create a new hole after currently allocated block, but only if we have enough space. If we don't, we simply allocate a bigger block so that we don't loose space
+	if (loc->size > (newsize + sizeof(heap_header_t) + sizeof(heap_footer_t))) { 
+		loc->size = newsize;	//Update header for return block
+
+		heap_footer_t *newfooter = (heap_footer_t*)((u32int)loc + newsize - sizeof(heap_footer_t)); //Write footer for return block
+		newfooter->header = loc;
+		newfooter->magic = HEAP_MAGIC;
+
+		heap_header_t *nextloc = (heap_header_t*)((u32int)loc + newsize); //Write header for new hole
+		nextloc->is_hole = true;
+		nextloc->magic = HEAP_MAGIC;
+		nextloc->size = ((u32int)footer - (u32int)nextloc + sizeof(heap_footer_t));
+
+		footer->header = nextloc;	//Write footer for new hole
+		footer->magic = HEAP_MAGIC;
+
+		insertIntoIndex(nextloc);
+	}
+	
+	m_free -= loc->size;
+
+	return (void*)((u32int)loc + sizeof(heap_header_t));
+}
+
+void Heap::free(void *ptr) {
+	if (ptr == 0) return;
+
+	heap_header_t *header = (heap_header_t*) ((u32int)ptr - sizeof(heap_header_t));
+	heap_footer_t *footer = (heap_footer_t*)((u32int)header + header->size - sizeof(heap_footer_t));
+	if (header->magic != HEAP_MAGIC or footer->magic != HEAP_MAGIC) return;
+
+	m_free += header->size;
+
+	//Unify left
+	heap_footer_t *prev_footer = (heap_footer_t*)((u32int)header - sizeof(heap_footer_t));
+	if (prev_footer->magic == HEAP_MAGIC && prev_footer->header->is_hole) {
+		header = prev_footer->header;
+		removeFromIndex(header);
+
+		footer->header = header;
+		header->size = ((u32int)footer - (u32int)header + sizeof(heap_footer_t));
+	}
+
+	//Unify right
+	heap_header_t *next_header = (heap_header_t*)((u32int)footer + sizeof(heap_footer_t));
+	if (next_header->magic == HEAP_MAGIC && next_header->is_hole) {
+		removeFromIndex(next_header);
+		footer = (heap_footer_t*)((u32int)footer + next_header->size);
+		
+		footer->header = header;
+		header->size = ((u32int)footer - (u32int)header + sizeof(heap_footer_t));
+	}
+
+	header->is_hole = true;
+
+	insertIntoIndex(header);
+
+	if ((u32int)footer == (m_end - sizeof(heap_footer_t)) and
+			header->size >= 0x2000 and (m_end - m_start > HEAP_MIN_SIZE)) {
+		contract();
+	}
+}