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#include "idt.hpp"
#include "portio.hpp"
#include "textoutput.hpp"
#include <array>
#include <cstdint>
#include <utility>
extern TextOutput& term;
static constexpr std::uint8_t TaskGate = 0x5;
static constexpr std::uint8_t IntrGate16 = 0x6;
static constexpr std::uint8_t TrapGate16 = 0x7;
static constexpr std::uint8_t IntrGate32 = 0xE;
static constexpr std::uint8_t TrapGate32 = 0xF;
struct idt_entry_bits {
std::uint32_t offset_low : 16;
std::uint32_t segment_selector : 16;
std::uint32_t rsvd : 8;
std::uint32_t gate_type : 4;
std::uint32_t rsvd2 : 1;
std::uint32_t dpl : 2;
std::uint32_t present : 1;
std::uint32_t offset_high : 16;
} __attribute__((packed));
static std::array<Callback, 48> callbacks;
extern "C"
void interruptGeneralHandler(Registers regs)
{
const auto& inum = regs.inum;
if (inum >= 32) {
if (inum >= 40)
outb(0xA0, 0x20);
outb(0x20, 0x20);
}
if (inum < callbacks.size()) {
if (auto cb = callbacks[inum]; cb) {
asm volatile("cli");
cb(regs);
asm volatile("sti");
}
}
}
template<std::size_t N>
struct StubEntry
{
static constexpr bool HasError = N == 8 || (N >= 10 && N <= 14) || N == 17 || N == 30;
__attribute__((naked))
static void stub() {
if constexpr (!HasError)
asm volatile("push $0x0");
asm volatile(R"(
pusha
push %0
cld
call interruptGeneralHandler
pop %%eax
popa
add $0x4, %%esp
iret
)" :: "i"(N));
}
static constexpr std::uint32_t segment(std::uint16_t gdt_idx, bool useLdt, std::uint16_t rpl) {
return gdt_idx | (useLdt ? 0x4 : 0x0) | (rpl & 0x3);
}
idt_entry_bits entry = {
.offset_low = (uint32_t)stub & 0xFFFF,
.segment_selector = segment(0x8, false, 0),
.gate_type = IntrGate32,
.dpl = 0,
.present = 1,
.offset_high = (uint32_t)stub >> 16
};
operator idt_entry_bits() const noexcept {
return entry;
}
};
static auto idt =
[]<std::size_t... ints>(std::index_sequence<ints...>) {
return std::array<idt_entry_bits, 256> { StubEntry<ints>()... };
}(std::make_index_sequence<48>{});
void idt_initialize()
{
auto idtr = reinterpret_cast<std::uint64_t>(idt.data());
idtr <<= 16;
idtr |= idt.size() * sizeof(idt[0]);
asm volatile("lidt %0" :: "m"(idtr));
}
void idt_register_callback(std::size_t num, Callback cb)
{
if (num < callbacks.size())
callbacks[num] = cb;
}
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