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#include "gdt.h"
#include <stdlib.h>
using seg = GDT::SegmentDescriptor;
GDT::GDT()
: segments{seg::make<0>(0, {.present = false}), // null segment
seg::make<0>(0, {.present = false}), // unused segment ???
seg::make<0xffffffff>(0, {.r_w = true, .exe = true, .segment = true}), // code segment
seg::make<0xffffffff>(0, {.r_w = true, .segment = true})} // data segment
{
Pointer gdtr{.limit = sizeof(segments) - 1, .base = reinterpret_cast<uint32_t>(segments)};
asm volatile("lgdt %0" : : "p"(gdtr));
printk("GDT installed at ", uhex{gdtr.base}, '\n');
}
uint16_t GDT::codeDescriptor() const {
return static_cast<uint16_t>(reinterpret_cast<const uint32_t>(&segments[2]) -
reinterpret_cast<const uint32_t>(&segments));
}
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