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#ifndef _X86_H_
#define _X86_H_
// Privilege levels
#define DPL_USER 0x3
#define DPL_KERNEL 0x0
// Selectors
#define LDT_SELECTOR 0x4
// Descriptor types for code and data segments
#define TYPE_DATA_READONLY 1
#define TYPE_DATA_READWRITE 3
#define TYPE_CODE_EXECONLY 9
#define TYPE_CODE_EXECREAD 11
// Descriptor types for system segments and gates
#define TYPE_LDT 2
#define TYPE_TASK_GATE 5
#define TYPE_TSS 9
#define TYPE_CALL_GATE 12
#define TYPE_TRAP_GATE 15
#define TYPE_INTERRUPT_GATE 14
// Descriptor system bit (S)
// For code or data segments
#define S_CODE_OR_DATA 1
// For TSS segment, LDT, call gate, interrupt gate, trap gate, task gate
#define S_SYSTEM 0
// D/B bit
#define DB_SEG 1
#define DB_SYS 0
// kernel code and data selectors in the GDT
#define GDT_KERNEL_CODE_SELECTOR 0x08
#define GDT_KERNEL_DATA_SELECTOR 0x10
// Disable hardware interrupts.
static inline void cli() {
asm volatile("cli");
}
// Enable hardware interrupts.
static inline void sti() {
asm volatile("sti");
}
// Halt the processor.
// External interrupts wake up the CPU, hence the cli instruction.
static inline void halt() {
while (1) asm volatile("cli\nhlt");
}
#endif
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