42_KFS/src/memory/memory.c

#include "memory.h"
#include "debug.h"
#include "kprintf.h"
#include "utils.h"

#include <stdint.h>

uint32_t *page_directory = &boot_page_directory;
uint32_t page_table_default[1024] __attribute__((aligned(PAGE_SIZE)));
uint32_t multiboot_page_table[1024] __attribute__((aligned(PAGE_SIZE)));
uint32_t mem_size;
multiboot_memory_map_t *mmap_addr;
multiboot_uint32_t mmap_length;

static void init_multiboot(multiboot_info_t *mbd, uint32_t magic)
{
	if (magic != MULTIBOOT_BOOTLOADER_MAGIC)
		kpanic("invalid magic number! (git good skill issue)");

	init_page_table(multiboot_page_table, 0);
	page_directory[1023] =
	    ((uint32_t)multiboot_page_table - HEAP_END) | 0x03;
	const size_t mbd_size = CEIL(
	    (uint32_t)mbd % PAGE_SIZE + sizeof(multiboot_info_t), PAGE_SIZE);

	// Index multiboot_info_t struct
	for (uint32_t i = 0; i < mbd_size; i++)
		multiboot_page_table[i] =
		    (((uint32_t)mbd + PAGE_SIZE * i) & PAGE_MASK) | INIT_FLAGS;
	multiboot_info_t *mbd_virt =
	    (multiboot_info_t *)(GET_PAGE_ADDR(1023, 0) +
	                         (uint32_t)mbd % PAGE_SIZE);

	// Index mbd->mmap_addr pointers
	for (uint32_t i = 0; i < mbd_virt->mmap_length; i++)
		multiboot_page_table[i + mbd_size] =
		    ((mbd_virt->mmap_addr + i * PAGE_SIZE) & PAGE_MASK) |
		    INIT_FLAGS;
	mmap_addr = (multiboot_memory_map_t *)(GET_PAGE_ADDR(1023, mbd_size) +
	                                       (uint32_t)mbd_virt->mmap_addr %
	                                           PAGE_SIZE);
	mmap_length = mbd_virt->mmap_length / sizeof(multiboot_memory_map_t);
}

void init_memory(multiboot_info_t *mbd, uint32_t magic)
{
	assert(page_directory);
	for (uint16_t i = 0; i < 0x300; i++)
		page_directory[i] = 0x02;
	init_page_table(page_table_default, 0);
	page_directory[0] = ((uint32_t)page_table_default - HEAP_END) | 0x03;
	init_multiboot(mbd, magic);
}