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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 <common.h>
#include <stdbool.h>
#include <stdint.h>
#define PAGE_DIRECTORY_SIZE 1024
#define PAGE_TABLE_SIZE 1024
#define PAGE_SIZE (4 * KiB)
#define PDE_PRESENT(x) x
#define PDE_WRITABLE(x) ((x) << 1)
#define PDE_USER(x) ((x) << 2)
#define PDE_WRITETHROUGH(x) ((x) << 3)
#define PDE_CACHE_DISABLE(x) ((x) << 4)
#define PDE_ACCESSED(x) ((x) << 5)
/* Never set (reserved by Intel) */
#define PDE_RESERVED(x) ((x) << 6)
#define PDE_PAGE_SIZE(x) ((x) << 7)
/* NOTE: Unused by the CPU, free to be used by us! */
#define PDE_UNUSED(x) ((x) << 8)
/* Page table address */
#define PDE_FRAME(x) ((x) & 0x7ffff000)
#define PDE_IS_PRESENT(pd_entry) ((*pd_entry) & 1)
#define GET_PD_INDEX(virtual_address) (((uint32_t) virtual_address) >> 22)
#define PDE_GET_TABLE(pd_entry) ((*pd_entry) & ~0xfff)
#define PTE_PRESENT(x) x
#define PTE_WRITABLE(x) ((x) << 1)
#define PTE_USER(x) ((x) << 2)
#define PTE_WRITETHROUGH(x) ((x) << 3)
#define PTE_CACHE_DISABLE(x) ((x) << 4)
#define PTE_ACCESSED(x) ((x) << 5)
#define PTE_DIRTY(x) ((x) << 6)
#define PTE_PAT(x) ((x) << 7)
#define PTE_GLOBAL(x) ((x) << 8)
/* NOTE: Unused by the CPU, free to be used by us! */
#define PTE_UNUSED(x) ((x) << 9)
/* Left shift by 12 because we only need the bits from the twelfth bit. */
#define PTE_FRAME(x) ((x) & 0x7ffff000)
#define PTE_IS_PRESENT(pt_entry) ((*pt_entry) & 1)
#define GET_PTE_FRAME(x) ((x) >> 12)
#define GET_PT_INDEX(virtual_address) \
((((uint32_t) virtual_address) >> 12) & 0x3ff)
#define ADD_ATTRIB(entry, attribute) (*entry |= (attribute))
#define VIRTUAL_ADDRESS(pd_index, pt_index) \
(((pd_index) << 22) | ((pt_index) << 12))
namespace VirtualMM
{
/*
* Loads a given page directory into CR0
*/
void load_page_directory(uint32_t *page_directory);
/*
* Switches the current page directory to a given page directory
*/
bool switch_page_directory(uint32_t *page_directory);
/*
* Initialize the virtual memory manager
*/
void initialize(void);
/*
* Map a physical address to a virtual address
*/
void map_page(void *physical_address, void *virtual_address);
/*
* Unmap a page starting at virtual address
*/
void unmap_page(void *virtual_address);
/*
* Find a virtual address with n consecutive free addresses.
*/
void *find_free_addresses(uint32_t n_pages);
/*
* Allocate and map n pages.
*/
void *alloc_pages(uint32_t n_pages);
/*
* Free n pages from the starting address.
*/
void free_pages(void *starting_address, uint32_t n_pages);
}
#endif
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