diff options
Diffstat (limited to 'src/stem/mem/gdt.c')
-rw-r--r-- | src/stem/mem/gdt.c | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/src/stem/mem/gdt.c b/src/stem/mem/gdt.c new file mode 100644 index 0000000..5aaad41 --- /dev/null +++ b/src/stem/mem/gdt.c @@ -0,0 +1,36 @@ +#include "gdt.h" +#include <stdlib.h> +#include <core/monitor.h> + +extern void gdt_flush(uint32_t); //ASM (idt_.asm) + +#define GDT_ENTRIES 5 + +static struct gdt_entry gdt_entries[GDT_ENTRIES]; +static struct gdt_ptr gdt_ptr; + +static void gdt_setGate(int num, uint32_t base, uint32_t limit, uint8_t access, uint8_t gran) { + gdt_entries[num].base_low = (base & 0xFFFF); + gdt_entries[num].base_middle = (base >> 16) & 0xFF; + gdt_entries[num].base_high = (base >> 24) & 0xFF; + + gdt_entries[num].limit_low = (limit & 0xFFFF); + gdt_entries[num].granularity = (limit >> 16) & 0x0F; + gdt_entries[num].granularity |= gran & 0xF0; + gdt_entries[num].access = access; +} + +void gdt_init() { + gdt_ptr.limit = (sizeof(struct gdt_entry) * GDT_ENTRIES) - 1; + gdt_ptr.base = (uint32_t)&gdt_entries; + + gdt_setGate(0, 0, 0, 0, 0); //Null segment + gdt_setGate(1, 0, 0xFFFFFFFF, 0x9A, 0xCF); //Kernel code segment + gdt_setGate(2, 0, 0xFFFFFFFF, 0x92, 0xCF); //Kernel data segment + gdt_setGate(3, 0, 0xFFFFFFFF, 0xFA, 0xCF); //User code segment + gdt_setGate(4, 0, 0xFFFFFFFF, 0xF2, 0xCF); //User data segment + + gdt_flush((uint32_t)&gdt_ptr); + + monitor_write("GDT ok\n"); +} |