30 lines
826 B
C
30 lines
826 B
C
#include "gdt.h"
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struct gdt_entry gdt[3];
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struct gdt_ptr gdtp;
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extern void gdt_flush(uint32_t);
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void gdt_set_gate(int num, uint32_t base, uint32_t limit, uint8_t access, uint8_t gran) {
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gdt[num].base_low = (base & 0xFFFF);
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gdt[num].base_middle = (base >> 16) & 0xFF;
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gdt[num].base_high = (base >> 24) & 0xFF;
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gdt[num].limit_low = (limit & 0xFFFF);
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gdt[num].granularity = (limit >> 16) & 0x0F;
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gdt[num].granularity |= gran & 0xF0;
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gdt[num].access = access;
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}
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void gdt_install() {
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gdtp.limit = (sizeof(struct gdt_entry) * 3) - 1;
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gdtp.base = (uint32_t)&gdt;
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gdt_set_gate(0, 0, 0, 0, 0); // Null segment
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gdt_set_gate(1, 0, 0xFFFFFFFF, 0x9A, 0xCF); // Code segment
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gdt_set_gate(2, 0, 0xFFFFFFFF, 0x92, 0xCF); // Data segment
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gdt_flush((uint32_t)&gdtp);
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}
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