Virtual memory & paging

[lunaix-os.git] / lunaix-os / kernel / asm / x86 / gdt.c

diff --git a/lunaix-os/kernel/asm/x86/gdt.c b/lunaix-os/kernel/asm/x86/gdt.c
new file mode 100644 (file)
index 0000000..41c597e
--- /dev/null
+++ b/lunaix-os/kernel/asm/x86/gdt.c
@@ -0,0 +1,23 @@
+#include <arch/x86/gdt.h>
+#include <stdint.h>
+
+#define GDT_ENTRY 5
+
+uint64_t _gdt[GDT_ENTRY];
+uint16_t _gdt_limit = sizeof(_gdt) - 1;
+
+void _set_gdt_entry(uint32_t index, uint32_t base, uint32_t limit, uint32_t flags) {
+    _gdt[index] = SEG_BASE_H(base) | flags | SEG_LIM_H(limit) | SEG_BASE_M(base);
+    _gdt[index] <<= 32;
+    _gdt[index] |= SEG_BASE_L(base) | SEG_LIM_L(limit);
+}
+
+ 
+void
+_init_gdt() {
+    _set_gdt_entry(0, 0, 0, 0);
+    _set_gdt_entry(1, 0, 0xfffff, SEG_R0_CODE);
+    _set_gdt_entry(2, 0, 0xfffff, SEG_R0_DATA);
+    _set_gdt_entry(3, 0, 0xfffff, SEG_R3_CODE);
+    _set_gdt_entry(4, 0, 0xfffff, SEG_R3_DATA);
+}
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