main.c

@@ -5,6 +5,7 @@
 #define ALIGN4(s) (((((s)-1)>>2)<<2)+4)
 #define BLOCK_SIZE sizeof(struct block)
 
+/// The memory's block header.
 struct block
 {
 	size_t size;
@@ -14,6 +15,10 @@ struct block
 
 struct block* freeList = NULL;
 
+/// Extends heap memory upwards, towards zero.
+/// @param [in] last The last block that the newly created block will link to.
+/// @param [in] s The size of the memory needed aligned by 4 bytes.
+/// @returns The new memory block.
 struct block* extend_heap(struct block* last, size_t s)
 {
 	struct block* b = sbrk(0);
@@ -31,6 +36,9 @@ struct block* extend_heap(struct block* last, size_t s)
 	return b;
 }
 
+/// Finds the first block that will fit the given size.
+/// @param [in] s The 4 byte aligned size to look for.
+/// @returns The matching available memory block.
 struct block* find_first(size_t s)
 {
 	struct block* current = freeList;
@@ -40,6 +48,8 @@ struct block* find_first(size_t s)
 	return current;
 }
 
+/// Finds the last memory block in the linked list to attach a new block to.
+/// @returns The last memory block.
 struct block* find_last()
 {
 	struct block* current = freeList;
@@ -49,6 +59,10 @@ struct block* find_last()
 	return current;
 }
 
+/// Will find or allocate a memory block.
+/// @param [in] size The size of the memory block to request.
+/// @returns The requested memory on the heap.
+/// @todo Fragmenting functionality.
 void* malloc(size_t size)
 {
 	struct block* b;
@@ -60,6 +74,10 @@ void* malloc(size_t size)
 		b = find_first(alignedSize);
 		if (!b)
 			b = extend_heap(find_last(), alignedSize);
+		/*
+		else
+		 	Fragment here if possible.
+		*/
 	}
 	else
 	{
@@ -73,6 +91,10 @@ void* malloc(size_t size)
 	return (char*)b + BLOCK_SIZE;
 }
 
+/// Will flag the provided memory as free and will defragment other blocks adjacent to it.
+/// @param [in] ptr The memory to flag as free.
+/// @note If all data after the provided memory is free, it will reduce the heap size.
+/// @todo Reverse defragmenting.
 void free(void* ptr)
 {
 	if (!ptr)
@@ -88,6 +110,8 @@ void free(void* ptr)
 		b->next = link->next;
 	}
 
+	// Reverse defragment here.
+
 	if (!b->next)
 		brk(b);
 }