#include "memorymanagement.h"

#include "string.h"

#include "kernel.h"

void memory_manager_init( memory_manager_t *memory_manager, size_t offset, size_t size )
{
	memset( memory_manager, 0, sizeof( memory_manager_t ) );

	memory_manager->offset = offset;
	memory_manager->size = size;
	memory_manager->free_ptr = memory_manager->offset;
	memory_manager->prev_ptr = 0xFFFFFFFF;
}

void memory_manager_init_with_buf( memory_manager_t *memory_manager, void *buf, size_t size )
{
	memset( memory_manager, 0, sizeof( memory_manager_t ) );

	memory_manager->offset = (uint32_t)buf;
	memory_manager->size = size;
	memory_manager->free_ptr = memory_manager->offset;
	memory_manager->prev_ptr = 0xFFFFFFFF;
}

void *memory_manager_allocate( memory_manager_t *memory_manager, size_t size )
{
	void *p = NULL;

	if( memory_manager->free_ptr - memory_manager->offset + size > memory_manager->size ) {
		kernel_panic( "Heap allocation out of memory (requested %d bytes, available %d)",
			size, size - ( memory_manager->free_ptr - memory_manager->offset ) );
	}

	p = (void *)memory_manager->free_ptr;
	memory_manager->prev_ptr = memory_manager->free_ptr;
	memory_manager->free_ptr += size;

	return p;
}

void memory_manager_deallocate( memory_manager_t *memory_manager, void **p )
{
	if( *p == NULL ) {
		kernel_panic( "Double free of pointer 0x%X in heap", *p );
	}

	// This actually doesn't work and we do it outside after free, when
	// a buffer has an optional semantic
	//*p = NULL;
	
	// are we freeing the previously allocated block, if yes, we can
	// adjust the free pointer
	if( (uint32_t)*p == memory_manager->prev_ptr ) {
		memory_manager->free_ptr = memory_manager->prev_ptr;
		memory_manager->prev_ptr = 0xFFFFFFFF;
	}
}