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David Goeke
2025-05-28 14:41:02 -05:00
commit 6d366537dd
73 changed files with 4448 additions and 0 deletions
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34
drivers/gdt.c Normal file
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#include <gdt.h>
#define GDT_ENTRIES 3
struct gdt_entry gdt[GDT_ENTRIES];
struct gdt_ptr gp;
extern void gdt_flush(uint32_t);
void gdt_install()
{
gp.limit = (sizeof(struct gdt_entry) * GDT_ENTRIES) - 1;
gp.base = (uint32_t)&gdt;
gdt_set_entry(0, 0, 0, 0, 0); /* Null segment */
gdt_set_entry(1, 0, 0xFFFFFFFF, 0x9A, 0xCF); /* Code segment */
gdt_set_entry(2, 0, 0xFFFFFFFF, 0x92, 0xCF); /* Data segment */
gdt_flush((uint32_t)&gp);
}
void gdt_set_entry(int num, uint32_t base, uint32_t limit, uint8_t access, uint8_t gran)
{
gdt[num].base_low = (base & 0xFFFF);
gdt[num].base_middle = (base >> 16) & 0xFF;
gdt[num].base_high = (base >> 24) & 0xFF;
gdt[num].limit_low = (limit & 0xFFFF);
gdt[num].granularity = (limit >> 16) & 0x0F;
gdt[num].granularity |= (gran & 0xF0);
gdt[num].access = access;
}