buddysystem.h

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#pragma once
 
#include "sys/list_head.h"
#include "klib/stdatomic.h"
#include "stdint.h"
 
#define MAX_BUDDYSYSTEM_GFP_ORDER 14
 
#define BBSTRUCT_OFFSET(page, element) \
    ((uint32_t) & (((page *)NULL)->element))
 
#define PG_FROM_BBSTRUCT(bbstruct, page, element) \
    ((page *)(((uint32_t)(bbstruct)) - BBSTRUCT_OFFSET(page, element)))
 
typedef struct bb_page_t {
    volatile unsigned long flags;
    uint32_t order;
    union {
        list_head siblings;
        list_head cache;
    } location;
} bb_page_t;
 
typedef struct bb_free_area_t {
    list_head free_list;
    int nr_free;
} bb_free_area_t;
 
typedef struct bb_instance_t {
    const char *name;
    bb_free_area_t free_area[MAX_BUDDYSYSTEM_GFP_ORDER];
    list_head free_pages_cache_list;
    unsigned long free_pages_cache_size;
    unsigned long size;
    bb_page_t *base_page;
    unsigned long pgs_size;
    unsigned long bbpg_offset;
} bb_instance_t;
 
bb_page_t *bb_alloc_pages(bb_instance_t *instance, unsigned int order);
 
void bb_free_pages(bb_instance_t *instance, bb_page_t *page);
 
bb_page_t *bb_alloc_page_cached(bb_instance_t *instance);
 
void bb_free_page_cached(bb_instance_t *instance, bb_page_t *page);
 
void buddy_system_init(
    bb_instance_t *instance,
    const char *name,
    void *pages_start,
    uint32_t bbpage_offset,
    uint32_t pages_stride,
    uint32_t pages_count);
 
void buddy_system_dump(bb_instance_t *instance);
 
unsigned long buddy_system_get_total_space(bb_instance_t *instance);
 
unsigned long buddy_system_get_free_space(bb_instance_t *instance);
 
unsigned long buddy_system_get_cached_space(bb_instance_t *instance);