/*
	This file is part of cpp-ethereum.

	cpp-ethereum is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	cpp-ethereum is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file VM.cpp
 * @author Gav Wood <i@gavwood.com>
 * @date 2014
 */

#include "VM.h"
#include <libethereum/ExtVM.h>
using namespace std;
using namespace dev;
using namespace dev::eth;

struct InstructionMetric
{
	int gasPriceTier;
	int args;
	int ret;
};

static array<InstructionMetric, 256> metrics()
{
	array<InstructionMetric, 256> s_ret;
	for (unsigned i = 0; i < 256; ++i)
	{
		InstructionInfo inst = instructionInfo((Instruction)i);
		s_ret[i].gasPriceTier = inst.gasPriceTier;
		s_ret[i].args = inst.args;
		s_ret[i].ret = inst.ret;
	}
	return s_ret;
}

bytesConstRef VM::go(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp, uint64_t _steps)
{
	// Reset leftovers from possible previous run
	m_curPC = 0;
	m_jumpDests.clear();

	m_stack.reserve((unsigned)c_stackLimit);

	unique_ptr<CallParameters> callParams;

	static const array<InstructionMetric, 256> c_metrics = metrics();

	auto memNeed = [](u256 _offset, dev::u256 _size) { return _size ? (bigint)_offset + _size : (bigint)0; };
	auto gasForMem = [](bigint _size) -> bigint
	{
		bigint s = _size / 32;
		return (bigint)c_memoryGas * s + s * s / c_quadCoeffDiv;
	};

	if (m_jumpDests.empty())
		for (unsigned i = 0; i < _ext.code.size(); ++i)
		{
			if (_ext.code[i] == (byte)Instruction::JUMPDEST)
				m_jumpDests.push_back(i);
			else if (_ext.code[i] >= (byte)Instruction::PUSH1 && _ext.code[i] <= (byte)Instruction::PUSH32)
				i += _ext.code[i] - (unsigned)Instruction::PUSH1 + 1;
		}
	u256 nextPC = m_curPC + 1;
	auto osteps = _steps;
	for (bool stopped = false; !stopped && _steps--; m_curPC = nextPC, nextPC = m_curPC + 1)
	{
		// INSTRUCTION...
		Instruction inst = (Instruction)_ext.getCode(m_curPC);
		auto metric = c_metrics[(int)inst];
		int gasPriceTier = metric.gasPriceTier;

		if (gasPriceTier == InvalidTier)
			BOOST_THROW_EXCEPTION(BadInstruction());

		// FEES...
		bigint runGas = c_tierStepGas[metric.gasPriceTier];
		bigint newTempSize = m_temp.size();
		bigint copySize = 0;

		// should work, but just seems to result in immediate errorless exit on initial execution. yeah. weird.
		//m_onFail = std::function<void()>(onOperation);

		require(metric.args, metric.ret);

		auto onOperation = [&]()
		{
			if (_onOp)
				_onOp(osteps - _steps - 1, inst, newTempSize > m_temp.size() ? (newTempSize - m_temp.size()) / 32 : bigint(0), runGas, io_gas, this, &_ext);
		};

		switch (inst)
		{
		case Instruction::SSTORE:
			if (!_ext.store(m_stack.back()) && m_stack[m_stack.size() - 2])
				runGas = c_sstoreSetGas;
			else if (_ext.store(m_stack.back()) && !m_stack[m_stack.size() - 2])
			{
				runGas = c_sstoreResetGas;
				_ext.sub.refunds += c_sstoreRefundGas;
			}
			else
				runGas = c_sstoreResetGas;
			break;

		case Instruction::SLOAD:
			runGas = c_sloadGas;
			break;

		// These all operate on memory and therefore potentially expand it:
		case Instruction::MSTORE:
			newTempSize = (bigint)m_stack.back() + 32;
			break;
		case Instruction::MSTORE8:
			newTempSize = (bigint)m_stack.back() + 1;
			break;
		case Instruction::MLOAD:
			newTempSize = (bigint)m_stack.back() + 32;
			break;
		case Instruction::RETURN:
			newTempSize = memNeed(m_stack.back(), m_stack[m_stack.size() - 2]);
			break;
		case Instruction::SHA3:
			runGas = c_sha3Gas + (m_stack[m_stack.size() - 2] + 31) / 32 * c_sha3WordGas;
			newTempSize = memNeed(m_stack.back(), m_stack[m_stack.size() - 2]);
			break;
		case Instruction::CALLDATACOPY:
			copySize = m_stack[m_stack.size() - 3];
			newTempSize = memNeed(m_stack.back(), m_stack[m_stack.size() - 3]);
			break;
		case Instruction::CODECOPY:
			copySize = m_stack[m_stack.size() - 3];
			newTempSize = memNeed(m_stack.back(), m_stack[m_stack.size() - 3]);
			break;
		case Instruction::EXTCODECOPY:
			copySize = m_stack[m_stack.size() - 4];
			newTempSize = memNeed(m_stack[m_stack.size() - 2], m_stack[m_stack.size() - 4]);
			break;

		case Instruction::JUMPDEST:
			runGas = 1;
			break;

		case Instruction::LOG0:
		case Instruction::LOG1:
		case Instruction::LOG2:
		case Instruction::LOG3:
		case Instruction::LOG4:
		{
			unsigned n = (unsigned)inst - (unsigned)Instruction::LOG0;
			runGas = c_logGas + c_logTopicGas * n + (bigint)c_logDataGas * m_stack[m_stack.size() - 2];
			newTempSize = memNeed(m_stack[m_stack.size() - 1], m_stack[m_stack.size() - 2]);
			break;
		}

		case Instruction::CALL:
		case Instruction::CALLCODE:
			runGas = (bigint)c_callGas + m_stack[m_stack.size() - 1];
			if (inst != Instruction::CALLCODE && !_ext.exists(asAddress(m_stack[m_stack.size() - 2])))
				runGas += c_callNewAccountGas;
			if (m_stack[m_stack.size() - 3] > 0)
				runGas += c_callValueTransferGas;
			newTempSize = std::max(memNeed(m_stack[m_stack.size() - 6], m_stack[m_stack.size() - 7]), memNeed(m_stack[m_stack.size() - 4], m_stack[m_stack.size() - 5]));
			break;

		case Instruction::CREATE:
		{
			newTempSize = memNeed(m_stack[m_stack.size() - 2], m_stack[m_stack.size() - 3]);
			runGas = c_createGas;
			break;
		}
		case Instruction::EXP:
		{
			auto expon = m_stack[m_stack.size() - 2];
			runGas = c_expGas + c_expByteGas * (32 - (h256(expon).firstBitSet() / 8));
			break;
		}
		default:;
		}

		newTempSize = (newTempSize + 31) / 32 * 32;
		if (newTempSize > m_temp.size())
			runGas += gasForMem(newTempSize) - gasForMem(m_temp.size());
		runGas += c_copyGas * ((copySize + 31) / 32);

		onOperation();

		if (io_gas < runGas)
			BOOST_THROW_EXCEPTION(OutOfGas());

		io_gas -= (u256)runGas;

		if (newTempSize > m_temp.size())
			m_temp.resize((size_t)newTempSize);

		// EXECUTE...
		switch (inst)
		{
		case Instruction::ADD:
			//pops two items and pushes S[-1] + S[-2] mod 2^256.
			m_stack[m_stack.size() - 2] += m_stack.back();
			m_stack.pop_back();
			break;
		case Instruction::MUL:
			//pops two items and pushes S[-1] * S[-2] mod 2^256.
			m_stack[m_stack.size() - 2] *= m_stack.back();
			m_stack.pop_back();
			break;
		case Instruction::SUB:
			m_stack[m_stack.size() - 2] = m_stack.back() - m_stack[m_stack.size() - 2];
			m_stack.pop_back();
			break;
		case Instruction::DIV:
			m_stack[m_stack.size() - 2] = m_stack[m_stack.size() - 2] ? m_stack.back() / m_stack[m_stack.size() - 2] : 0;
			m_stack.pop_back();
			break;
		case Instruction::SDIV:
			m_stack[m_stack.size() - 2] = m_stack[m_stack.size() - 2] ? s2u(u2s(m_stack.back()) / u2s(m_stack[m_stack.size() - 2])) : 0;
			m_stack.pop_back();
			break;
		case Instruction::MOD:
			m_stack[m_stack.size() - 2] = m_stack[m_stack.size() - 2] ? m_stack.back() % m_stack[m_stack.size() - 2] : 0;
			m_stack.pop_back();
			break;
		case Instruction::SMOD:
			m_stack[m_stack.size() - 2] = m_stack[m_stack.size() - 2] ? s2u(u2s(m_stack.back()) % u2s(m_stack[m_stack.size() - 2])) : 0;
			m_stack.pop_back();
			break;
		case Instruction::EXP:
		{
			auto base = m_stack.back();
			auto expon = m_stack[m_stack.size() - 2];
			m_stack.pop_back();
			m_stack.back() = (u256)boost::multiprecision::powm((bigint)base, (bigint)expon, bigint(1) << 256);
			break;
		}
		case Instruction::NOT:
			m_stack.back() = ~m_stack.back();
			break;
		case Instruction::LT:
			m_stack[m_stack.size() - 2] = m_stack.back() < m_stack[m_stack.size() - 2] ? 1 : 0;
			m_stack.pop_back();
			break;
		case Instruction::GT:
			m_stack[m_stack.size() - 2] = m_stack.back() > m_stack[m_stack.size() - 2] ? 1 : 0;
			m_stack.pop_back();
			break;
		case Instruction::SLT:
			m_stack[m_stack.size() - 2] = u2s(m_stack.back()) < u2s(m_stack[m_stack.size() - 2]) ? 1 : 0;
			m_stack.pop_back();
			break;
		case Instruction::SGT:
			m_stack[m_stack.size() - 2] = u2s(m_stack.back()) > u2s(m_stack[m_stack.size() - 2]) ? 1 : 0;
			m_stack.pop_back();
			break;
		case Instruction::EQ:
			m_stack[m_stack.size() - 2] = m_stack.back() == m_stack[m_stack.size() - 2] ? 1 : 0;
			m_stack.pop_back();
			break;
		case Instruction::ISZERO:
			m_stack.back() = m_stack.back() ? 0 : 1;
			break;
		case Instruction::AND:
			m_stack[m_stack.size() - 2] = m_stack.back() & m_stack[m_stack.size() - 2];
			m_stack.pop_back();
			break;
		case Instruction::OR:
			m_stack[m_stack.size() - 2] = m_stack.back() | m_stack[m_stack.size() - 2];
			m_stack.pop_back();
			break;
		case Instruction::XOR:
			m_stack[m_stack.size() - 2] = m_stack.back() ^ m_stack[m_stack.size() - 2];
			m_stack.pop_back();
			break;
		case Instruction::BYTE:
			m_stack[m_stack.size() - 2] = m_stack.back() < 32 ? (m_stack[m_stack.size() - 2] >> (unsigned)(8 * (31 - m_stack.back()))) & 0xff : 0;
			m_stack.pop_back();
			break;
		case Instruction::ADDMOD:
			m_stack[m_stack.size() - 3] = m_stack[m_stack.size() - 3] ? u256((bigint(m_stack.back()) + bigint(m_stack[m_stack.size() - 2])) % m_stack[m_stack.size() - 3]) : 0;
			m_stack.pop_back();
			m_stack.pop_back();
			break;
		case Instruction::MULMOD:
			m_stack[m_stack.size() - 3] = m_stack[m_stack.size() - 3] ? u256((bigint(m_stack.back()) * bigint(m_stack[m_stack.size() - 2])) % m_stack[m_stack.size() - 3]) : 0;
			m_stack.pop_back();
			m_stack.pop_back();
			break;
		case Instruction::SIGNEXTEND:
			if (m_stack.back() < 31)
			{
				unsigned const testBit(m_stack.back() * 8 + 7);
				u256& number = m_stack[m_stack.size() - 2];
				u256 mask = ((u256(1) << testBit) - 1);
				if (boost::multiprecision::bit_test(number, testBit))
					number |= ~mask;
				else
					number &= mask;
			}
			m_stack.pop_back();
			break;
		case Instruction::SHA3:
		{
			unsigned inOff = (unsigned)m_stack.back();
			m_stack.pop_back();
			unsigned inSize = (unsigned)m_stack.back();
			m_stack.pop_back();
			m_stack.push_back(sha3(bytesConstRef(m_temp.data() + inOff, inSize)));
			break;
		}
		case Instruction::ADDRESS:
			m_stack.push_back(fromAddress(_ext.myAddress));
			break;
		case Instruction::ORIGIN:
			m_stack.push_back(fromAddress(_ext.origin));
			break;
		case Instruction::BALANCE:
		{
			m_stack.back() = _ext.balance(asAddress(m_stack.back()));
			break;
		}
		case Instruction::CALLER:
			m_stack.push_back(fromAddress(_ext.caller));
			break;
		case Instruction::CALLVALUE:
			m_stack.push_back(_ext.value);
			break;
		case Instruction::CALLDATALOAD:
		{
			if ((bigint)m_stack.back() + 31 < _ext.data.size())
				m_stack.back() = (u256)*(h256 const*)(_ext.data.data() + (size_t)m_stack.back());
			else if ((bigint)m_stack.back() >= _ext.data.size())
				m_stack.back() = u256();
			else
			{
				h256 r;
				for (uint64_t i = (unsigned)m_stack.back(), e = (unsigned)m_stack.back() + (uint64_t)32, j = 0; i < e; ++i, ++j)
					r[j] = i < _ext.data.size() ? _ext.data[i] : 0;
				m_stack.back() = (u256)r;
			}
			break;
		}
		case Instruction::CALLDATASIZE:
			m_stack.push_back(_ext.data.size());
			break;
		case Instruction::CODESIZE:
			m_stack.push_back(_ext.code.size());
			break;
		case Instruction::EXTCODESIZE:
			m_stack.back() = _ext.codeAt(asAddress(m_stack.back())).size();
			break;
		case Instruction::CALLDATACOPY:
		case Instruction::CODECOPY:
		case Instruction::EXTCODECOPY:
		{
			Address a;
			if (inst == Instruction::EXTCODECOPY)
			{
				a = asAddress(m_stack.back());
				m_stack.pop_back();
			}
			unsigned offset = (unsigned)m_stack.back();
			m_stack.pop_back();
			u256 index = m_stack.back();
			m_stack.pop_back();
			unsigned size = (unsigned)m_stack.back();
			m_stack.pop_back();
			unsigned sizeToBeCopied;
			switch(inst)
			{
			case Instruction::CALLDATACOPY:
				sizeToBeCopied = index + (bigint)size > (u256)_ext.data.size() ? (u256)_ext.data.size() < index ? 0 : _ext.data.size() - (unsigned)index : size;
				memcpy(m_temp.data() + offset, _ext.data.data() + (unsigned)index, sizeToBeCopied);
				break;
			case Instruction::CODECOPY:
				sizeToBeCopied = index + (bigint)size > (u256)_ext.code.size() ? (u256)_ext.code.size() < index ? 0 : _ext.code.size() - (unsigned)index : size;
				memcpy(m_temp.data() + offset, _ext.code.data() + (unsigned)index, sizeToBeCopied);
				break;
			case Instruction::EXTCODECOPY:
				sizeToBeCopied = index + (bigint)size > (u256)_ext.codeAt(a).size() ? (u256)_ext.codeAt(a).size() < index ? 0 : _ext.codeAt(a).size() - (unsigned)index : size;
				memcpy(m_temp.data() + offset, _ext.codeAt(a).data() + (unsigned)index, sizeToBeCopied);
				break;
			default:
				// this is unreachable, but if someone introduces a bug in the future, he may get here.
				assert(false);
				BOOST_THROW_EXCEPTION(InvalidOpcode() << errinfo_comment("CALLDATACOPY, CODECOPY or EXTCODECOPY instruction requested."));
				break;
			}
			memset(m_temp.data() + offset + sizeToBeCopied, 0, size - sizeToBeCopied);
			break;
		}
		case Instruction::GASPRICE:
			m_stack.push_back(_ext.gasPrice);
			break;
		case Instruction::BLOCKHASH:
			m_stack.back() = (u256)_ext.blockhash(m_stack.back());
			break;
		case Instruction::COINBASE:
			m_stack.push_back((u160)_ext.currentBlock.coinbaseAddress);
			break;
		case Instruction::TIMESTAMP:
			m_stack.push_back(_ext.currentBlock.timestamp);
			break;
		case Instruction::NUMBER:
			m_stack.push_back(_ext.currentBlock.number);
			break;
		case Instruction::DIFFICULTY:
			m_stack.push_back(_ext.currentBlock.difficulty);
			break;
		case Instruction::GASLIMIT:
			m_stack.push_back(_ext.currentBlock.gasLimit);
			break;
		case Instruction::PUSH1:
		case Instruction::PUSH2:
		case Instruction::PUSH3:
		case Instruction::PUSH4:
		case Instruction::PUSH5:
		case Instruction::PUSH6:
		case Instruction::PUSH7:
		case Instruction::PUSH8:
		case Instruction::PUSH9:
		case Instruction::PUSH10:
		case Instruction::PUSH11:
		case Instruction::PUSH12:
		case Instruction::PUSH13:
		case Instruction::PUSH14:
		case Instruction::PUSH15:
		case Instruction::PUSH16:
		case Instruction::PUSH17:
		case Instruction::PUSH18:
		case Instruction::PUSH19:
		case Instruction::PUSH20:
		case Instruction::PUSH21:
		case Instruction::PUSH22:
		case Instruction::PUSH23:
		case Instruction::PUSH24:
		case Instruction::PUSH25:
		case Instruction::PUSH26:
		case Instruction::PUSH27:
		case Instruction::PUSH28:
		case Instruction::PUSH29:
		case Instruction::PUSH30:
		case Instruction::PUSH31:
		case Instruction::PUSH32:
		{
			int i = (int)inst - (int)Instruction::PUSH1 + 1;
			nextPC = m_curPC + 1;
			m_stack.push_back(0);
			for (; i--; nextPC++)
				m_stack.back() = (m_stack.back() << 8) | _ext.getCode(nextPC);
			break;
		}
		case Instruction::POP:
			m_stack.pop_back();
			break;
		case Instruction::DUP1:
		case Instruction::DUP2:
		case Instruction::DUP3:
		case Instruction::DUP4:
		case Instruction::DUP5:
		case Instruction::DUP6:
		case Instruction::DUP7:
		case Instruction::DUP8:
		case Instruction::DUP9:
		case Instruction::DUP10:
		case Instruction::DUP11:
		case Instruction::DUP12:
		case Instruction::DUP13:
		case Instruction::DUP14:
		case Instruction::DUP15:
		case Instruction::DUP16:
		{
			auto n = 1 + (int)inst - (int)Instruction::DUP1;
			m_stack.push_back(m_stack[m_stack.size() - n]);
			break;
		}
		case Instruction::SWAP1:
		case Instruction::SWAP2:
		case Instruction::SWAP3:
		case Instruction::SWAP4:
		case Instruction::SWAP5:
		case Instruction::SWAP6:
		case Instruction::SWAP7:
		case Instruction::SWAP8:
		case Instruction::SWAP9:
		case Instruction::SWAP10:
		case Instruction::SWAP11:
		case Instruction::SWAP12:
		case Instruction::SWAP13:
		case Instruction::SWAP14:
		case Instruction::SWAP15:
		case Instruction::SWAP16:
		{
			unsigned n = (int)inst - (int)Instruction::SWAP1 + 2;
			auto d = m_stack.back();
			m_stack.back() = m_stack[m_stack.size() - n];
			m_stack[m_stack.size() - n] = d;
			break;
		}
		case Instruction::MLOAD:
		{
			m_stack.back() = (u256)*(h256 const*)(m_temp.data() + (unsigned)m_stack.back());
			break;
		}
		case Instruction::MSTORE:
		{
			*(h256*)&m_temp[(unsigned)m_stack.back()] = (h256)m_stack[m_stack.size() - 2];
			m_stack.pop_back();
			m_stack.pop_back();
			break;
		}
		case Instruction::MSTORE8:
		{
			m_temp[(unsigned)m_stack.back()] = (byte)(m_stack[m_stack.size() - 2] & 0xff);
			m_stack.pop_back();
			m_stack.pop_back();
			break;
		}
		case Instruction::SLOAD:
			m_stack.back() = _ext.store(m_stack.back());
			break;
		case Instruction::SSTORE:
			_ext.setStore(m_stack.back(), m_stack[m_stack.size() - 2]);
			m_stack.pop_back();
			m_stack.pop_back();
			break;
		case Instruction::JUMP:
			nextPC = m_stack.back();
			if (find(m_jumpDests.begin(), m_jumpDests.end(), (uint64_t)nextPC) == m_jumpDests.end() || nextPC > numeric_limits<uint64_t>::max() )
				BOOST_THROW_EXCEPTION(BadJumpDestination());
			m_stack.pop_back();
			break;
		case Instruction::JUMPI:
			if (m_stack[m_stack.size() - 2])
			{
				nextPC = m_stack.back();
				if (find(m_jumpDests.begin(), m_jumpDests.end(), (uint64_t)nextPC) == m_jumpDests.end() || nextPC > numeric_limits<uint64_t>::max() )
					BOOST_THROW_EXCEPTION(BadJumpDestination());
			}
			m_stack.pop_back();
			m_stack.pop_back();
			break;
		case Instruction::PC:
			m_stack.push_back(m_curPC);
			break;
		case Instruction::MSIZE:
			m_stack.push_back(m_temp.size());
			break;
		case Instruction::GAS:
			m_stack.push_back(io_gas);
			break;
		case Instruction::JUMPDEST:
			break;
		case Instruction::LOG0:
			_ext.log({}, bytesConstRef(m_temp.data() + (unsigned)m_stack[m_stack.size() - 1], (unsigned)m_stack[m_stack.size() - 2]));
			m_stack.pop_back();
			m_stack.pop_back();
			break;
		case Instruction::LOG1:
			_ext.log({m_stack[m_stack.size() - 3]}, bytesConstRef(m_temp.data() + (unsigned)m_stack[m_stack.size() - 1], (unsigned)m_stack[m_stack.size() - 2]));
			m_stack.pop_back();
			m_stack.pop_back();
			m_stack.pop_back();
			break;
		case Instruction::LOG2:
			_ext.log({m_stack[m_stack.size() - 3], m_stack[m_stack.size() - 4]}, bytesConstRef(m_temp.data() + (unsigned)m_stack[m_stack.size() - 1], (unsigned)m_stack[m_stack.size() - 2]));
			m_stack.pop_back();
			m_stack.pop_back();
			m_stack.pop_back();
			m_stack.pop_back();
			break;
		case Instruction::LOG3:
			_ext.log({m_stack[m_stack.size() - 3], m_stack[m_stack.size() - 4], m_stack[m_stack.size() - 5]}, bytesConstRef(m_temp.data() + (unsigned)m_stack[m_stack.size() - 1], (unsigned)m_stack[m_stack.size() - 2]));
			m_stack.pop_back();
			m_stack.pop_back();
			m_stack.pop_back();
			m_stack.pop_back();
			m_stack.pop_back();
			break;
		case Instruction::LOG4:
			_ext.log({m_stack[m_stack.size() - 3], m_stack[m_stack.size() - 4], m_stack[m_stack.size() - 5], m_stack[m_stack.size() - 6]}, bytesConstRef(m_temp.data() + (unsigned)m_stack[m_stack.size() - 1], (unsigned)m_stack[m_stack.size() - 2]));
			m_stack.pop_back();
			m_stack.pop_back();
			m_stack.pop_back();
			m_stack.pop_back();
			m_stack.pop_back();
			m_stack.pop_back();
			break;
		case Instruction::CREATE:
		{
			u256 endowment = m_stack.back();
			m_stack.pop_back();
			unsigned initOff = (unsigned)m_stack.back();
			m_stack.pop_back();
			unsigned initSize = (unsigned)m_stack.back();
			m_stack.pop_back();

			if (_ext.balance(_ext.myAddress) >= endowment && _ext.depth < 1024)
				m_stack.push_back((u160)_ext.create(endowment, io_gas, bytesConstRef(m_temp.data() + initOff, initSize), _onOp));
			else
				m_stack.push_back(0);
			break;
		}
		case Instruction::CALL:
		case Instruction::CALLCODE:
		{
			if (!callParams)
				callParams.reset(new CallParameters);

			callParams->gas = m_stack.back();
			if (m_stack[m_stack.size() - 3] > 0)
				callParams->gas += c_callStipend;
			m_stack.pop_back();
			callParams->codeAddress = asAddress(m_stack.back());
			m_stack.pop_back();
			callParams->value = m_stack.back();
			m_stack.pop_back();

			unsigned inOff = (unsigned)m_stack.back();
			m_stack.pop_back();
			unsigned inSize = (unsigned)m_stack.back();
			m_stack.pop_back();
			unsigned outOff = (unsigned)m_stack.back();
			m_stack.pop_back();
			unsigned outSize = (unsigned)m_stack.back();
			m_stack.pop_back();

			if (_ext.balance(_ext.myAddress) >= callParams->value && _ext.depth < 1024)
			{
				callParams->onOp = _onOp;
				callParams->senderAddress = _ext.myAddress;
				callParams->receiveAddress = inst == Instruction::CALL ? callParams->codeAddress : callParams->senderAddress;
				callParams->data = bytesConstRef(m_temp.data() + inOff, inSize);
				callParams->out = bytesRef(m_temp.data() + outOff, outSize);
				m_stack.push_back(_ext.call(*callParams));
			}
			else
				m_stack.push_back(0);

			io_gas += callParams->gas;
			break;
		}
		case Instruction::RETURN:
		{
			unsigned b = (unsigned)m_stack.back();
			m_stack.pop_back();
			unsigned s = (unsigned)m_stack.back();
			m_stack.pop_back();
			return bytesConstRef(m_temp.data() + b, s);
		}
		case Instruction::SUICIDE:
		{
			Address dest = asAddress(m_stack.back());
			_ext.suicide(dest);
			// ...follow through to...
		}
		case Instruction::STOP:
			return bytesConstRef();
		}
	}

	if (_steps == (uint64_t)-1)
		BOOST_THROW_EXCEPTION(StepsDone());
	return bytesConstRef();
}