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#ifndef GDT_H
#define GDT_H
#include <Types.h>
#include <MemoryOperations.h>
// Define access options
#define PRESENT (1 << 7) // Present bit
#define USER (3 << 5) // Descriptor privelege level
#define NSYSTEMSEG (1 << 4) // Descriptor type
#define EXEC (1 << 3) // Executable bit
#define GROWDOWN (1 << 2) // Direction bit
#define WRITABLE (1 << 1) // Readable/Writable bit
#define ACCESSED 1 // Accessed bit
// Define flags byte
#define PAGEGRAN (1 << 3) // Granularity flag
#define HIGHSIZE (1 << 2) // Size flag
#define LONGMODEON (1 << 1) // Long-mode flag
// Set of segment descriptors assign acesses bits
#define DATA_RO 0x00 // data seg, grows up, read only, not accessed
#define DATA_ROA 0x01 // data seg, grows up, read only, accessed
#define DATA_RW 0x02 // data seg, grows up, read/write, not accessed
#define DATA_RWA 0x03 // data seg, grows up, read/write, accessed
#define DATA_ROD 0x04 // data seg, grows down, read only, not accessed
#define DATA_RODGA 0x05 // data seg, grows down, read only, accessed
#define DATA_RWD 0x06 // data seg, grows down, read/write, not accessed
#define DATA_RWDA 0x07 // data seg, grows down, read/write, accessed
#define CODE_EO 0x08 // code seg, conforming, execute only, not accessed
#define CODE_EOA 0x09 // code seg, conforming, execute only, accessed
#define CODE_ER 0x0A // code seg, conforming, execute/read, not accessed
#define CODE_ERA 0x0B // code seg, conforming, execute/read, accessed
#define CODE_EONC 0x0C // code seg, not conforming, execute only, not accessed
#define CODE_EONCA 0x0D // code seg, not conforming, execute only, accessed
#define CODE_ERNC 0x0E // code seg, not conforming, execute/read, not accessed
#define CODE_ERNCA 0x0F // code seg, not conforming, execute/read, accessed
class DescSeg32 // Segment descriptor
{
private:
uint16 limitLow;
uint16 baseLow;
uint8 baseMiddle;
uint8 access;
uint8 limitMiddle; // one word limit value 19:16
uint8 flags; // one word located 55:52 bits in descriptor
uint8 baseHight;
public:
DescSeg32(uint32 base, uint32 limit, uint8 access, uint8 flags);
void setDescriptor(uint32 base, uint32 limit, uint8 access, uint8 flags);
uint64 getDescriptor();
static uint64 flatCodeKernel();
static uint64 flatDataKernel();
static uint64 flatCodeUser();
static uint64 flatDataUser();
};
#ifdef __cplusplus
extern "C" {
#endif
extern void SWITCHTOGDT(uint64 descriptor);
#ifdef __cplusplus
};
#endif
class MngGdt
{
private:
const static uint8 size = 10;
static uint64 gdt[size];
static bool isInitialize;
static bool gdtLoaded;
uint16 codeSegmentKern;
uint8 currIdx;
MngGdt &operator=(const MngGdt &) = default;
public:
MngGdt();
MngGdt(const MngGdt &) = delete;
bool addDescriptor(uint64 desc); // 0 - not set descriptor, 1 - set
bool loadGdt(); // 0 - if GDT is not loaded, 1 - loaded
uint16 getCodeSegmentKernel();
static MngGdt &getInstance();
};
extern MngGdt mngGdt;
#endif
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