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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/>.
*/
#include <common.h>
#include <kernel/halt.h>
#include <libk/stdio.h>
#include <mm/page_table_allocator.h>
#include <mm/physical_mm.h>
#include <mm/virtual_mm.h>
#include <stddef.h>
namespace PageTableAllocator
{
uint32_t *l_page_directory = 0;
uint32_t *l_heap = NULL;
uint16_t l_table_index = 0;
static void
make_table(uint32_t *table_address)
{
uint32_t *table = table_address;
for (uint32_t i = 0; i < 1024; i++)
table[i] = PTE_FRAME((uint32_t) PhysicalMM::allocate_block())
| PTE_PRESENT(1) | PTE_WRITABLE(1);
/* TODO: Just find an unused pd_entry instead */
void *starting_address = VirtualMM::find_free_addresses(4 * KiB);
uint32_t *pd_entry = &l_page_directory[GET_PD_INDEX(starting_address)];
*pd_entry = PDE_FRAME((uint32_t) table) | PDE_PRESENT(1) | PDE_WRITABLE(1);
l_heap = (uint32_t *) starting_address;
l_table_index = 0;
}
void
initialize(void)
{
/* We can't just do this in allocate() because make_table() depends on
* VirtualMM::find_free_addresses() */
if (l_page_directory != VirtualMM::get_page_directory())
l_page_directory = VirtualMM::get_page_directory();
/* Initial table */
if (l_heap == NULL)
make_table((uint32_t *) (7 * MiB));
}
uint32_t *
allocate(void)
{
uint32_t *next_table = l_heap + (l_table_index * 4 * KiB);
l_table_index++;
return next_table;
}
}
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