BarinkOS/src/kernel/MMU.cpp

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#include "MMU.h"
void MMU::enable(){
//set each entry to not present
int i;
for(i = 0; i < 1024; i++)
{
// This sets the following flags to the pages:
// Supervisor: Only kernel-mode can access them
// Write Enabled: It can be both read from and written to
// Not Present: The page table is not present
this->page_directory[i] = 0x00000002;
}
// holds the physical address where we want to start mapping these pages to.
// in this case, we want to map these pages to the very beginning of memory.
//we will fill all 1024 entries in the table, mapping 4 megabytes
for(unsigned int i = 0; i < 1024; i++)
{
// As the address is page aligned, it will always leave 12 bits zeroed.
// Those bits are used by the attributes ;)
first_page_table[i] = (i * 0x1000) | 3; // attributes: supervisor level, read/write, present.
}
// attributes: supervisor level, read/write, present
this->page_directory[0] = ((unsigned int)first_page_table) | 3;
loadPageDirectory(this->page_directory);
enablePaging();
}