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#include "gdt.h"
static void gdt_set_gate(int idx, uint32_t base, uint32_t limit, uint8_t access, uint8_t gran)
{
/* Setup the descriptor base address */
gdt[idx].base_low = (base & 0xFFFF);
gdt[idx].base_middle = (base >> 16) & 0xFF;
gdt[idx].base_high = (base >> 24) & 0xFF;
/* Setup the descriptor limits */
gdt[idx].limit_low = (limit & 0xFFFF);
gdt[idx].granularity = ((limit >> 16) & 0x0F);
/* Finally, set up the granularity and access flags */
gdt[idx].granularity |= (gran & 0xF0);
gdt[idx].access = access;
}
void gdt_init(void)
{
gp.limit = sizeof(gdt) - 1;
gp.base = (uint32_t)&gdt;
/* null segment */
gdt_set_gate(0, 0, 0, 0, 0);
/* code segment */
gdt_set_gate(1, 0, 0xFFFFFFFF, 0x9A, 0xCF);
/* data segment */
gdt_set_gate(2, 0, 0xFFFFFFFF, 0x92, 0xCF);
gdt_flush((uint32_t)&gp);
}
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