1 files changed, 25 insertions, 0 deletions
diff --git a/src/gdt.cc b/src/gdt.cc
new file mode 100644
index 0000000..202fe77
--- /dev/null
+++ b/src/gdt.cc
@@ -0,0 +1,25 @@
+#include "gdt.h"
+
+GDT::SegmentDescriptor::SegmentDescriptor(uint32_t base, uint32_t limit, uint8_t type) {
+  base_low = base & 0xffff;
+  base_high = (base >> 16) & 0xff;
+  base_vhigh = (base >> 24) & 0xff;
+}
+uint32_t GDT::SegmentDescriptor::base() const {
+  uint32_t base = base_vhigh;
+  base = (base << 8) + base_high;
+  base = (base << 8) + base_low;
+  return base;
+}
+uint32_t GDT::SegmentDescriptor::limit() const {
+  return 0;
+}
+
+GDT::GDT()
+    : segments{{0, 0, 0},                               // null segment
+               {0, 64 * 1024 * 1024 /* 64MB */, 0x9a},  // code segment
+               {0, 64 * 1024 * 1024 /* 64MB */, 0x92}}  // data segment
+{
+  Pointer gdtr{.limit = sizeof(segments) - 1, .base = reinterpret_cast<uint32_t>(segments)};
+  asm volatile("lgdt %0" : : "p"(gdtr));
+}