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/*
* bubbl
* Copyright (C) 2025 Raghuram Subramani <raghus2247@gmail.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __mm_virtual_mm_h
#define __mm_virtual_mm_h
#include <stdbool.h>
#include <stdint.h>
#define PAGE_DIRECTORY_SIZE 1024
#define PAGE_TABLE_SIZE 1024
#define PAGE_DIRECTORY_INDEX(virtual_address) ((virtual_address >> 22) & 0x3ff)
#define PAGE_TABLE_INDEX(virtual_address) ((virtual_address >> 12) & 0x3ff)
#define SET_PDE_PRESENT(x) x
#define SET_PDE_WRITABLE(x) (x << 1)
#define SET_PDE_USER(x) (x << 2)
#define SET_PDE_WRITETHROUGH(x) (x << 3)
#define SET_PDE_CACHE_DISABLE(x) (x << 4)
#define SET_PDE_ACCESSED(x) (x << 5)
/* Never set (reserved by Intel) */
#define SET_PDE_RESERVED(x) (x << 6)
#define SET_PDE_PAGE_SIZE(x) (x << 7)
#define SET_PDE_GLOBAL(x) (x << 8)
/* NOTE: Unused by the CPU, free to be used by us! */
#define SET_PDE_UNUSED(x) (x << 9)
/* Page table address */
#define SET_PDE_FRAME(x) (x << 11)
#define GET_PDE_FRAME(x) (*x >> 11)
#define SET_PTE_PRESENT(x) x
#define SET_PTE_WRITABLE(x) (x << 1)
#define SET_PTE_USER(x) (x << 2)
#define SET_PTE_WRITETHROUGH(x) (x << 3)
#define SET_PTE_CACHE_DISABLE(x) (x << 4)
#define SET_PTE_ACCESSED(x) (x << 5)
#define SET_PTE_DIRTY(x) (x << 6)
#define SET_PTE_PAT(x) (x << 7)
#define SET_PTE_GLOBAL(x) (x << 8)
/* NOTE: Unused by the CPU, free to be used by us! */
#define SET_PTE_UNUSED(x) (x << 9)
/* MAX: 0xFFFFF000 */
#define SET_PTE_FRAME(x) (x << 11)
#define PTE_IS_PRESENT(x) (x & 1)
#define GET_PTE_FRAME(x) (*x >> 11)
#define ADD_ATTRIB(entry, attribute) (*entry |= (attribute))
/*
* Given a page table entry, it sets the frame to a newly allocated address,
* and sets the present bit to false.
*/
bool virtual_mm_allocate_page(uint32_t *pt_entry);
/*
* Given a page table entry, it sets the entry to 0 (therefore zero-ing the
* frame and present bit).
*/
bool virtual_mm_free_page(uint32_t *pt_entry);
/*
* Given a page table and virtual address, it returns a pointer to the page
* table entry referenced by the virtual address.
*/
uint32_t *virtual_mm_lookup_table(uint32_t *page_table, uint32_t virtual_addr);
/*
* Given a page directory and virtual address, it returns a pointer to the page
* directory entry referenced by the virtual address.
*/
uint32_t *virtual_mm_lookup_directory(uint32_t *page_directory,
uint32_t virtual_addr);
/*
* Loads a given page directory into CR0
*/
void virtual_mm_load_page_directory(uint32_t *page_directory);
/*
* Switches the current page directory to a given page directory
*/
bool virtual_mm_switch_page_directory(uint32_t *page_directory);
/*
* Flushes the given TLB entry
*/
void virtual_mm_flush_tlb_entry(uint32_t *virtual_addr);
/*
* Map a given physical address to a virtual address
*/
bool virtual_mm_map_page(uint32_t *physical_addr, uint32_t *virtual_addr);
/*
* Initialize the virtual memory manager
*/
void virtual_mm_initialize(void);
#endif
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