gdt.h

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#ifndef _GDT_H_
#define _GDT_H_

#include <types.h>

#define KERNEL_CODE_SEGMENT             0x08
#define KERNEL_DATA_SEGMENT             0x10
#define KERNEL_STACK_SEGMENT    (KERNEL_DATA_SEGMENT)


#define USER_CODE_SEGMENT               0x1B
#define USER_DATA_SEGMENT               0x23
#define USER_STACK_SEGMENT              (USER_DATA_SEGMENT)


//#define SIZE_OF_GDT_ENTRY 8

struct x86_segment_descriptor
{
        /* Double mot de poids faible */
        uint16_t segment_limit_15_0; 
        uint16_t base_address_15_0;  
        /* Double mot de poids fort */
        uint8_t base_address_23_16; 
        uint8_t segment_type:4;                 
        uint8_t descriptor_type:1;      
        uint8_t dpl:2; 
        uint8_t present:1; 
        uint8_t segment_limit_19_16:4; 
        uint8_t available:1; 
        uint8_t zero:1; 
        uint8_t operation_size:1; 
        uint8_t granularity:1; 
        uint8_t base_address_31_24; 
} __attribute__ ((packed, aligned (8)));


typedef struct tss {
        uint16_t    previous_task, __previous_task_unused;
        uint32_t    esp0;
        uint16_t    ss0, __ss0_unused;
        uint32_t    esp1;
        uint16_t    ss1, __ss1_unused;
        uint32_t    esp2;
        uint16_t    ss2, __ss2_unused;
        uint32_t    cr3;
        uint32_t    eip, eflags, eax, ecx, edx, ebx, esp, ebp, esi, edi;
        uint16_t    es, __es_unused;
        uint16_t    cs, __cs_unused;
        uint16_t    ss, __ss_unused;
        uint16_t    ds, __ds_unused;
        uint16_t    fs, __fs_unused;
        uint16_t    gs, __gs_unused;
        uint16_t    ldt_selector, __ldt_sel_unused;
        uint16_t    debug_flag, io_map;
} __attribute__ ((packed)) tss_t;

void gdt_setup(size_t ram_size);

void init_tss(uint32_t stack_address);
tss_t* get_default_tss();

#endif