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#include "gdt.h"
#include "../Helpers/types.h"
#include "../Helpers/memory.h"
//Declare global vars
GdtDescriptorStruct GDT_DESCRIPTORS[4];
GdtPointerStruct GDT_POINTER;
//Adapt parameter to the gdt descriptor structure
void gdt_initGdtDesc(u32 base, u32 limit, u8 access, u8 flags, GdtDescriptorStruct *Descriptor){
Descriptor->limit1 = limit & 0xFFFF;
Descriptor->base1 = base & 0xFFFF;
Descriptor->base2 = (base & 0xFF0000) >> 16;
Descriptor->access = access;
Descriptor->limit2 = (limit & 0xF0000 ) >> 16;
Descriptor->flags = flags & 0xFF;
Descriptor->base3 = (base & 0xFF000000) >> 24;
}
//Copy the gdt into mémory and load it
void gdt_loadGdt(){
//Init default segment
gdt_initGdtDesc(0x0,0x0,0x0,0x0, &GDT_DESCRIPTORS[0]);
//Init code segment
gdt_initGdtDesc(0x0,0xFFFFF,0x9A,0x0D, &GDT_DESCRIPTORS[1]);
//Init data segment
gdt_initGdtDesc(0x0,0xFFFFF,0x92,0x0D, &GDT_DESCRIPTORS[2]);
//Init stack segment
gdt_initGdtDesc(0x00B00000,0x00000500,0x96,0x0D, &GDT_DESCRIPTORS[3]);
//Init GDT Pointer
GDT_POINTER.size=4*sizeof(GDT_DESCRIPTORS);
GDT_POINTER.segment=0x00007E00;
//Copy Gdt into memory and init registers
memcpy((u32)GDT_DESCRIPTORS, (u32)GDT_POINTER.segment, (u32)GDT_POINTER.size);
//Load the GDT
__asm__("lgdtl (%0);"
:
:"r"(&GDT_POINTER)
);
}
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