src/gdt.cc


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#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));
}