/* static */ const machine::op_map machine::OPERATIONS {{
	{op_t::ADD, [](machine *m){m->binop_func(std::plus<>());}},
	{op_t::SUB, [](machine *m){m->binop_func(std::minus<>());}},
	{op_t::INC, [](machine *m){m->stack.top()++;}},
	{op_t::DEC, [](machine *m){m->stack.top()--;}},
	{op_t::AND, [](machine *m){m->binop_func(std::bit_and<>());}},
	{op_t::OR,  [](machine *m){m->binop_func(std::bit_or<>());}},
	{op_t::NOT, [](machine *m){m->stack.top() = ~m->stack.top();}},
	{op_t::XOR, [](machine *m){m->binop_func(std::bit_xor<>());}},
	{op_t::SHR, [](machine *m){m->binop_func([](uint16_t a, uint16_t b){return a >> b;});}},
	{op_t::SHL, [](machine *m){m->binop_func([](uint16_t a, uint16_t b){return a << b;});}},

	{op_t::TGT, [](machine *m){m->comp_func(std::greater<>());}},
	{op_t::TLT, [](machine *m){m->comp_func(std::less<>());}},
	{op_t::TEQ, [](machine *m){m->comp_func(std::equal_to<>());}},
	{op_t::TSZ, [](machine *m){m->comp_func([](uint16_t t, uint16_t){return t == 0;});}},

	// SET,SSET special
	{op_t::LOAD,    &machine::load_func},
	{op_t::STORE,   &machine::store_func},
	{op_t::BRANCH,  [](machine *m){m->terminate = true;}},
	{op_t::BRZERO,  [](machine *m){m->terminate = true;}},
	{op_t::IBRANCH, [](machine *m){m->terminate = true;}},
	{op_t::CALL,    [](machine *m){m->terminate = true;}},
	{op_t::RETURN,  [](machine *m){m->terminate = true;}},
	{op_t::STOP,    [](machine *m){m->terminate = true;}},
	{op_t::OUT,     [](machine *m){std::cout << m->stack.top() << '\n';}},

	{op_t::DROP,  [](machine* m){m->stack.pop();}},
	{op_t::DUP,   [](machine* m){m->stack.push(m->stack.top());}},
	{op_t::SWAP,  &machine::swap_func},
	{op_t::RSD3,  [](machine *m){m->terminate = true;}},
	{op_t::RSU3,  [](machine *m){m->terminate = true;}},
	{op_t::TUCK2, [](machine *m){m->terminate = true;}},
	{op_t::TUCK3, [](machine *m){m->terminate = true;}},
	{op_t::COPY3, [](machine *m){m->terminate = true;}},
	// PUSH special
	{op_t::POP,   [](machine *m){m->terminate = true;}},
}};

void machine::set_func(uint16_t v)
{
	this->stack.push(v);
}

void machine::load_func()
{
	uint16_t addr = this->stack.top();
	this->stack.pop();
	this->stack.push(this->mem.at(addr));
}

void machine::store_func()
{
	uint16_t addr = this->stack.top();
	this->stack.pop();
	uint16_t val = this->stack.top();
	this->stack.pop();
	this->mem.at(addr) = val;
}

void machine::swap_func()
{
	uint16_t a = this->stack.top();
	this->stack.pop();
	uint16_t b = this->stack.top();
	this->stack.pop();
	this->stack.push(a);
	this->stack.push(b);
}

void machine::binop_func(std::function<uint16_t(uint16_t, uint16_t)> op)
{
	uint16_t a = this->stack.top();
	this->stack.pop();
	uint16_t b = this->stack.top();
	this->stack.pop();
	this->stack.push(op(b, a));
}

void machine::comp_func(std::function<bool(uint16_t, uint16_t)> op)
{
	uint16_t top = this->stack.top();
	this->stack.pop();
	uint16_t next = this->stack.top(); // no peeking..
	this->stack.push(top); // restore
	// sets nth bit (zero) to result of op
	this->flags ^= (-static_cast<uint8_t>(op(top, next)) ^ this->flags)
		& (1 << static_cast<uint8_t>(machine::flagbit::ZERO));
}