112 lines
2.1 KiB
C++
112 lines
2.1 KiB
C++
#include "intcode.hpp"
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#include <iostream>
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namespace intcode {
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BadInstruction::BadInstruction(char const* what)
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: std::runtime_error{what} {}
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Machine::Machine() : rom_{}, ram_{}, pc_{0}, base_{0} {}
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Machine::Machine(std::vector<ValueType> ram)
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: rom_{ram}, ram_{}, pc_{0}, base_{0} {}
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namespace {
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auto Ref(Machine & m, ValueType instruction, std::size_t k, ValueType p)
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-> ValueType & {
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auto &v = m.At(k);
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switch (instruction / p % 10) {
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case 0:
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return m.At(v);
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case 1:
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return v;
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case 2:
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return m.Rel(v);
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default:
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throw BadInstruction{"invalid addressing mode"};
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}
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}
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}
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auto Machine::At(std::size_t i) -> ValueType & {
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return i < rom_.size() ? rom_[i] : ram_[i];
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}
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auto Machine::Rel(std::size_t i) -> ValueType & {
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return At(base_ + i);
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}
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auto Machine::Step() -> std::variant<Input, Output, Halt> {
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for (;;) {
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auto instruction = At(pc_);
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auto a = [=]() -> auto & { return Ref(*this, instruction, pc_+1, 100); };
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auto b = [=]() -> auto & { return Ref(*this, instruction, pc_+2, 1000); };
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auto c = [=]() -> auto & { return Ref(*this, instruction, pc_+3, 10000); };
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switch (instruction % 100) {
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case 1:
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c() = a() + b();
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pc_ += 4;
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break;
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case 2:
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c() = a() * b();
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pc_ += 4;
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break;
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case 3: {
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auto &pos = a();
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pc_ += 2;
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return Input{pos};
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}
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case 4: {
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auto val = a();
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pc_ += 2;
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return Output{val};
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}
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case 5:
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pc_ = a() ? b() : pc_ + 3;
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break;
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case 6:
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pc_ = a() ? pc_ + 3 : b();
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break;
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case 7:
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c() = a() < b();
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pc_ += 4;
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break;
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case 8:
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c() = a() == b();
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pc_ += 4;
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break;
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case 9:
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base_ += a();
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pc_ += 2;
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break;
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case 99:
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return Halt{};
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default:
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throw BadInstruction{"invalid opcode"};
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}
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}
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}
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auto ParseStream(std::istream &in) -> std::vector<ValueType> {
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ValueType x;
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std::string str;
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std::vector<ValueType> result;
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while (std::getline(in, str, ',')) {
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result.push_back(std::stol(str));
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}
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return result;
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}
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}
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