void Compiler::appendFunctionSelector(ContractDefinition const& _contract)
{
map<FixedHash<4>, FunctionTypePointer> interfaceFunctions = _contract.getInterfaceFunctions();
map<FixedHash<4>, const eth::AssemblyItem> callDataUnpackerEntryPoints;
FunctionDefinition const* fallback = _contract.getFallbackFunction();
eth::AssemblyItem notFound = m_context.newTag();
// shortcut messages without data if we have many functions in order to be able to receive
// ether with constant gas
if (interfaceFunctions.size() > 5 || fallback)
{
m_context << eth::Instruction::CALLDATASIZE << eth::Instruction::ISZERO;
m_context.appendConditionalJumpTo(notFound);
}
// retrieve the function signature hash from the calldata
if (!interfaceFunctions.empty())
CompilerUtils(m_context).loadFromMemory(0, IntegerType(CompilerUtils::dataStartOffset * 8), true);
// stack now is: 1 0 <funhash>
for (auto const& it: interfaceFunctions)
{
callDataUnpackerEntryPoints.insert(std::make_pair(it.first, m_context.newTag()));
m_context << eth::dupInstruction(1) << u256(FixedHash<4>::Arith(it.first)) << eth::Instruction::EQ;
m_context.appendConditionalJumpTo(callDataUnpackerEntryPoints.at(it.first));
}
m_context.appendJumpTo(notFound);
m_context << notFound;
if (fallback)
{
eth::AssemblyItem returnTag = m_context.pushNewTag();
fallback->accept(*this);
m_context << returnTag;
appendReturnValuePacker(FunctionType(*fallback).getReturnParameterTypes());
}
else
m_context << eth::Instruction::STOP; // function not found
for (auto const& it: interfaceFunctions)
{
FunctionTypePointer const& functionType = it.second;
solAssert(functionType->hasDeclaration(), "");
CompilerContext::LocationSetter locationSetter(m_context, functionType->getDeclaration());
m_context << callDataUnpackerEntryPoints.at(it.first);
eth::AssemblyItem returnTag = m_context.pushNewTag();
appendCalldataUnpacker(functionType->getParameterTypes());
m_context.appendJumpTo(m_context.getFunctionEntryLabel(functionType->getDeclaration()));
m_context << returnTag;
appendReturnValuePacker(functionType->getReturnParameterTypes());
}
}
