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#include <apos/vmem.h>
#include <apos/pmem.h>
#include <apos/mem.h>
#include <apos/string.h>
#include <apos/mem_nodes.h>
enum block_status {
FREE = 0, USED = 1
};
struct block_wrapper {
enum block_status status;
struct mem_region n;
};
struct block_region {
size_t used_blocks;
struct sp_node sp_n;
};
static struct sp_root root_region = (struct sp_root){0};
#define MAX_BLOCKS \
((BASE_PAGE_SIZE - sizeof(struct block_region)) / sizeof(struct block_wrapper))
#define block_region(b) \
((struct block_region *)((size_t)(b) & ~(BASE_PAGE_SIZE - 1)))
#define region_container(b) \
container_of(b, struct block_region, sp_n)
#define block_container(b) \
container_of(b, struct block_wrapper, n)
#define region_to_array(r) \
((struct block_wrapper *)((char *)(r) + sizeof(struct block_region)))
static struct block_region *__create_region()
{
struct block_region *r = (struct block_region *)alloc_page(BASE_PAGE, 0);
memset(r, FREE, BASE_PAGE_SIZE);
return r;
}
void init_mem_blocks()
{
sp_root(root_region) = &__create_region()->sp_n;
}
static void __destroy_mem_block(struct sp_node *n)
{
if(!n)
return;
__destroy_mem_block(sp_left(n));
__destroy_mem_block(sp_right(n));
struct block_region *r = block_region(n);
free_page(BASE_PAGE, (vm_t)r);
}
void destroy_mem_blocks()
{
__destroy_mem_block(sp_root(root_region));
}
static struct mem_region *__find_free_block(struct block_region *h)
{
struct block_wrapper *w = region_to_array(h);
for(size_t i = 0; i < MAX_BLOCKS; ++i){
if(w[i].status != FREE)
continue;
w[i].status = USED;
return &w[i].n;
}
return 0;
}
static void __region_insert(struct block_region *r)
{
struct sp_node *n = sp_root(root_region), *p = NULL;
enum sp_dir d = LEFT;
r->sp_n = (struct sp_node){0};
while(n){
struct block_region *t = region_container(n);
p = n;
if(r->used_blocks < t->used_blocks){
n = sp_left(n);
d = LEFT;
}
else if(r->used_blocks > t->used_blocks){
n = sp_right(n);
d = RIGHT;
}
else if(r < t) {
n = sp_left(n);
d = LEFT;
}
else {
n = sp_right(n);
d = RIGHT;
}
}
sp_insert(&sp_root(root_region), p, &r->sp_n, d);
}
static void __region_remove(struct block_region *r)
{
sp_remove(&sp_root(root_region), &r->sp_n);
}
static void __update_regions(struct block_region *r)
{
__region_remove(r);
__region_insert(r);
}
struct mem_region *get_mem_node()
{
struct sp_node *n = sp_root(root_region);
while(n){
struct block_region *r = region_container(n);
if(r->used_blocks != MAX_BLOCKS){
r->used_blocks++;
__update_regions(r);
return __find_free_block(r);
}
n = sp_left(n);
}
/* we need to allocate a new region */
struct block_region *r = __create_region();
r->used_blocks++;
__region_insert(r);
return __find_free_block(r);
}
void free_mem_node(struct mem_region *m)
{
struct block_wrapper *w = block_container(m);
w->status = FREE;
struct block_region *r = block_region(w);
r->used_blocks--;
__update_regions(r);
}
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