pmm.h

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#ifndef KERNEL_PMM_H
#define KERNEL_PMM_H
 
#include <kernel/memory.h>
#include <kernel/types.h>
 
#include <utils/bits.h>
 
#include <multiboot.h>
#include <stdbool.h>
 
#define PMM_INVALID_PAGEFRAME (0xFFFFFFFFUL)
 
#define TOTAL_PAGEFRAMES_COUNT (ADDRESS_SPACE_SIZE / PAGE_SIZE)
 
enum page_flags {
    PAGE_AVAILABLE = BIT(0), 
    PAGE_COW = BIT(1),       
};
 
struct page {
    uint8_t flags;    
    uint8_t refcount; 
};
 
extern struct page pmm_pageframes[TOTAL_PAGEFRAMES_COUNT];
 
#define TO_PFN(_pageframe) (((native_t)(_pageframe)) >> PAGE_SHIFT)
#define FROM_PFN(_pageframe) ((_pageframe) << PAGE_SHIFT)
 
static inline paddr_t page_address(const struct page *page)
{
    return FROM_PFN((page - pmm_pageframes) / sizeof(*page));
}
 
static inline struct page *pfn_to_page(unsigned int pfn)
{
    return &pmm_pageframes[pfn];
}
 
static inline struct page *address_to_page(paddr_t addr)
{
    return pfn_to_page(TO_PFN(addr));
}
 
struct page *page_get(struct page *page);
 
void page_put(struct page *page);
 
static inline bool page_is_cow(struct page *page)
{
    return page->flags & PAGE_COW;
}
 
bool pmm_init(struct multiboot_info *);
 
paddr_t pmm_allocate_pages(size_t size);
 
void pmm_free_pages(paddr_t pageframe, size_t size);
 
#define pmm_allocate() pmm_allocate_pages(PAGE_SIZE)
 
#define pmm_free(pageframe) pmm_free_pages(pageframe, PAGE_SIZE)
 
#endif /* KERNEL_PMM_H */