text: /*
  	This file is part of solidity.
  
  	solidity 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.
  
  	solidity 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 solidity.  If not, see <http://www.gnu.org/licenses/>.
  */
  /**
   * Component that transforms internal Wasm representation to binary.
   */
  
  #include <libyul/backends/wasm/BinaryTransform.h>
  
  #include <libyul/Exceptions.h>
  #include <libsolutil/CommonData.h>
  #include <libsolutil/Visitor.h>
  
  #include <boost/range/adaptor/reversed.hpp>
  #include <boost/range/adaptor/map.hpp>
  #include <boost/range/adaptor/transformed.hpp>
  
  using namespace std;
  using namespace solidity;
  using namespace solidity::yul;
  using namespace solidity::yul::wasm;
  using namespace solidity::util;
  
  namespace
  {
  
  bytes toBytes(uint8_t _b)
  {
  	return bytes(1, _b);
  }
  
  enum class LimitsKind: uint8_t
  {
  	Min = 0x00,
  	MinMax = 0x01,
  };
  
  enum class Mutability: uint8_t
  {
  	Const = 0x00,
  	Var = 0x01,
  };
  
  enum class Section: uint8_t
  {
  	CUSTOM = 0x00,
  	TYPE = 0x01,
  	IMPORT = 0x02,
  	FUNCTION = 0x03,
  	MEMORY = 0x05,
  	GLOBAL = 0x06,
  	EXPORT = 0x07,
  	CODE = 0x0a
  };
  
  bytes toBytes(Section _s)
  {
  	return toBytes(uint8_t(_s));
  }
  
  enum class ValueType: uint8_t
  {
  	Void = 0x40,
  	Function = 0x60,
  	I64 = 0x7e,
  	I32 = 0x7f
  };
  
  bytes toBytes(ValueType _vt)
  {
  	return toBytes(uint8_t(_vt));
  }
  
  ValueType toValueType(wasm::Type _type)
  {
  	if (_type == wasm::Type::i32)
  		return ValueType::I32;
  	else if (_type == wasm::Type::i64)
  		return ValueType::I64;
  	else
  		yulAssert(false, "Invalid wasm variable type");
  }
  
  enum class Export: uint8_t
  {
  	Function = 0x0,
  	Memory = 0x2
  };
  
  bytes toBytes(Export _export)
  {
  	return toBytes(uint8_t(_export));
  }
  
  enum class Opcode: uint8_t
  {
  	Unreachable = 0x00,
  	Nop = 0x01,
  	Block = 0x02,
  	Loop = 0x03,
  	If = 0x04,
  	Else = 0x05,
  	Try = 0x06,
  	Catch = 0x07,
  	Throw = 0x08,
  	Rethrow = 0x09,
  	BrOnExn = 0x0a,
  	End = 0x0b,
  	Br = 0x0c,
  	BrIf = 0x0d,
  	BrTable = 0x0e,
  	Return = 0x0f,
  	Call = 0x10,
  	CallIndirect = 0x11,
  	ReturnCall = 0x12,
  	ReturnCallIndirect = 0x13,
  	Drop = 0x1a,
  	Select = 0x1b,
  	LocalGet = 0x20,
  	LocalSet = 0x21,
  	LocalTee = 0x22,
  	GlobalGet = 0x23,
  	GlobalSet = 0x24,
  	I32Const = 0x41,
  	I64Const = 0x42,
  };
  
  bytes toBytes(Opcode _o)
  {
  	return toBytes(uint8_t(_o));
  }
  
  Opcode constOpcodeFor(ValueType _type)
  {
  	if (_type == ValueType::I32)
  		return Opcode::I32Const;
  	else if (_type == ValueType::I64)
  		return Opcode::I64Const;
  	else
  		yulAssert(false, "Values of this type cannot be used with const opcode");
  }
  
  static map<string, uint8_t> const builtins = {
  	{"i32.load", 0x28},
  	{"i64.load", 0x29},
  	{"i32.load8_s", 0x2c},
  	{"i32.load8_u", 0x2d},
  	{"i32.load16_s", 0x2e},
  	{"i32.load16_u", 0x2f},
  	{"i64.load8_s", 0x30},
  	{"i64.load8_u", 0x31},
  	{"i64.load16_s", 0x32},
  	{"i64.load16_u", 0x33},
  	{"i64.load32_s", 0x34},
  	{"i64.load32_u", 0x35},
  	{"i32.store", 0x36},
  	{"i64.store", 0x37},
  	{"i32.store8", 0x3a},
  	{"i32.store16", 0x3b},
  	{"i64.store8", 0x3c},
  	{"i64.store16", 0x3d},
  	{"i64.store32", 0x3e},
  	{"memory.size", 0x3f},
  	{"memory.grow", 0x40},
  	{"i32.eqz", 0x45},
  	{"i32.eq", 0x46},
  	{"i32.ne", 0x47},
  	{"i32.lt_s", 0x48},
  	{"i32.lt_u", 0x49},
  	{"i32.gt_s", 0x4a},
  	{"i32.gt_u", 0x4b},
  	{"i32.le_s", 0x4c},
  	{"i32.le_u", 0x4d},
  	{"i32.ge_s", 0x4e},
  	{"i32.ge_u", 0x4f},
  	{"i64.eqz", 0x50},
  	{"i64.eq", 0x51},
  	{"i64.ne", 0x52},
  	{"i64.lt_s", 0x53},
  	{"i64.lt_u", 0x54},
  	{"i64.gt_s", 0x55},
  	{"i64.gt_u", 0x56},
  	{"i64.le_s", 0x57},
  	{"i64.le_u", 0x58},
  	{"i64.ge_s", 0x59},
  	{"i64.ge_u", 0x5a},
  	{"i32.clz", 0x67},
  	{"i32.ctz", 0x68},
  	{"i32.popcnt", 0x69},
  	{"i32.add", 0x6a},
  	{"i32.sub", 0x6b},
  	{"i32.mul", 0x6c},
  	{"i32.div_s", 0x6d},
  	{"i32.div_u", 0x6e},
  	{"i32.rem_s", 0x6f},
  	{"i32.rem_u", 0x70},
  	{"i32.and", 0x71},
  	{"i32.or", 0x72},
  	{"i32.xor", 0x73},
  	{"i32.shl", 0x74},
  	{"i32.shr_s", 0x75},
  	{"i32.shr_u", 0x76},
  	{"i32.rotl", 0x77},
  	{"i32.rotr", 0x78},
  	{"i64.clz", 0x79},
  	{"i64.ctz", 0x7a},
  	{"i64.popcnt", 0x7b},
  	{"i64.add", 0x7c},
  	{"i64.sub", 0x7d},
  	{"i64.mul", 0x7e},
  	{"i64.div_s", 0x7f},
  	{"i64.div_u", 0x80},
  	{"i64.rem_s", 0x81},
  	{"i64.rem_u", 0x82},
  	{"i64.and", 0x83},
  	{"i64.or", 0x84},
  	{"i64.xor", 0x85},
  	{"i64.shl", 0x86},
  	{"i64.shr_s", 0x87},
  	{"i64.shr_u", 0x88},
  	{"i64.rotl", 0x89},
  	{"i64.rotr", 0x8a},
  	{"i32.wrap_i64", 0xa7},
  	{"i64.extend_i32_s", 0xac},
  	{"i64.extend_i32_u", 0xad},
  };
  
  bytes lebEncode(uint64_t _n)
  {
  	bytes encoded;
  	while (_n > 0x7f)
  	{
  		encoded.emplace_back(uint8_t(0x80 | (_n & 0x7f)));
  		_n >>= 7;
  	}
  	encoded.emplace_back(_n);
  	return encoded;
  }
  
  bytes lebEncodeSigned(int64_t _n)
  {
  	if (_n >= 0 && _n < 0x40)
  		return toBytes(uint8_t(uint64_t(_n) & 0xff));
  	else if (-_n > 0 && -_n < 0x40)
  		return toBytes(uint8_t(uint64_t(_n + 0x80) & 0xff));
  	else
  		return toBytes(uint8_t(0x80 | uint8_t(_n & 0x7f))) + lebEncodeSigned(_n / 0x80);
  }
  
  bytes prefixSize(bytes _data)
  {
  	size_t size = _data.size();
  	return lebEncode(size) + move(_data);
  }
  
  bytes makeSection(Section _section, bytes _data)
  {
  	return toBytes(_section) + prefixSize(move(_data));
  }
  
  /// This is a kind of run-length-encoding of local types.
  vector<pair<size_t, ValueType>> groupLocalVariables(vector<VariableDeclaration> _localVariables)
  {
  	vector<pair<size_t, ValueType>> localEntries;
  
  	size_t entrySize = 0;
  	ValueType entryType = ValueType::I32; // Any type would work here
  	for (VariableDeclaration const& localVariable: _localVariables)
  	{
  		ValueType variableType = toValueType(localVariable.type);
  
  		if (variableType != entryType)
  		{
  			if (entrySize > 0)
  				localEntries.emplace_back(entrySize, entryType);
  
  			entryType = variableType;
  			entrySize = 0;
  		}
  
  		++entrySize;
  	}
  	if (entrySize > 0)
  		localEntries.emplace_back(entrySize, entryType);
  
  	return localEntries;
  }
  
  }
  
  bytes BinaryTransform::run(Module const& _module)
  {
  	map<Type, vector<string>> const types = typeToFunctionMap(_module.imports, _module.functions);
  
  	map<string, size_t> const globalIDs = enumerateGlobals(_module);
  	map<string, size_t> const functionIDs = enumerateFunctions(_module);
  	map<string, size_t> const functionTypes = enumerateFunctionTypes(types);
  
  	yulAssert(globalIDs.size() == _module.globals.size(), "");
  	yulAssert(functionIDs.size() == _module.imports.size() + _module.functions.size(), "");
  	yulAssert(functionTypes.size() == functionIDs.size(), "");
  	yulAssert(functionTypes.size() >= types.size(), "");
  
  	bytes ret{0, 'a', 's', 'm'};
  	// version
  	ret += bytes{1, 0, 0, 0};
  	ret += typeSection(types);
  	ret += importSection(_module.imports, functionTypes);
  	ret += functionSection(_module.functions, functionTypes);
  	ret += memorySection();
  	ret += globalSection(_module.globals);
  	ret += exportSection(functionIDs);
  
  	map<string, pair<size_t, size_t>> subModulePosAndSize;
  	for (auto const& sub: _module.subModules)
  	{
  		// TODO should we prefix and / or shorten the name?
  		bytes data = BinaryTransform::run(sub.second);
  		size_t length = data.size();
  		ret += customSection(sub.first, move(data));
  		subModulePosAndSize[sub.first] = {ret.size() - length, length};
  	}
  
  	BinaryTransform bt(
  		move(globalIDs),
  		move(functionIDs),
  		move(functionTypes),
  		move(subModulePosAndSize)
  	);
  
  	ret += bt.codeSection(_module.functions);
  	return ret;
  }
  
  bytes BinaryTransform::operator()(Literal const& _literal)
  {
  	return std::visit(GenericVisitor{
  		[&](uint32_t _value) -> bytes { return toBytes(Opcode::I32Const) + lebEncodeSigned(static_cast<int32_t>(_value)); },
  		[&](uint64_t _value) -> bytes { return toBytes(Opcode::I64Const) + lebEncodeSigned(static_cast<int64_t>(_value)); },
  	}, _literal.value);
  }
  
  bytes BinaryTransform::operator()(StringLiteral const&)
  {
  	// TODO is this used?
  	yulAssert(false, "String literals not yet implemented");
  }
  
  bytes BinaryTransform::operator()(LocalVariable const& _variable)
  {
  	return toBytes(Opcode::LocalGet) + lebEncode(m_locals.at(_variable.name));
  }
  
  bytes BinaryTransform::operator()(GlobalVariable const& _variable)
  {
  	return toBytes(Opcode::GlobalGet) + lebEncode(m_globalIDs.at(_variable.name));
  }
  
  bytes BinaryTransform::operator()(BuiltinCall const& _call)
  {
  	// We need to avoid visiting the arguments of `dataoffset` and `datasize` because
  	// they are references to object names that should not end up in the code.
  	if (_call.functionName == "dataoffset")
  	{
  		string name = get<StringLiteral>(_call.arguments.at(0)).value;
  		return toBytes(Opcode::I64Const) + lebEncodeSigned(static_cast<int64_t>(m_subModulePosAndSize.at(name).first));
  	}
  	else if (_call.functionName == "datasize")
  	{
  		string name = get<StringLiteral>(_call.arguments.at(0)).value;
  		return toBytes(Opcode::I64Const) + lebEncodeSigned(static_cast<int64_t>(m_subModulePosAndSize.at(name).second));
  	}
  
  	bytes args = visit(_call.arguments);
  
  	if (_call.functionName == "unreachable")
  		return toBytes(Opcode::Unreachable);
  	else if (_call.functionName == "nop")
  		return toBytes(Opcode::Nop);
  	else if (_call.functionName == "drop")
  		return toBytes(Opcode::Drop);
  	else
  	{
  		yulAssert(builtins.count(_call.functionName), "Builtin " + _call.functionName + " not found");
  		bytes ret = move(args) + toBytes(builtins.at(_call.functionName));
  		if (
  			_call.functionName.find(".load") != string::npos ||
  			_call.functionName.find(".store") != string::npos
  		)
  			// Alignment hint and offset. Interpreters ignore the alignment. JITs/AOTs can take it
  			// into account to generate more efficient code but if the hint is invalid it could
  			// actually be more expensive. It's best to hint at 1-byte alignment if we don't plan
  			// to control the memory layout accordingly.
  			ret += bytes{{0, 0}}; // 2^0 == 1-byte alignment
  
  		return ret;
  	}
  }
  
  bytes BinaryTransform::operator()(FunctionCall const& _call)
  {
  	return visit(_call.arguments) + toBytes(Opcode::Call) + lebEncode(m_functionIDs.at(_call.functionName));
  }
  
  bytes BinaryTransform::operator()(LocalAssignment const& _assignment)
  {
  	return
  		std::visit(*this, *_assignment.value) +
  		toBytes(Opcode::LocalSet) +
  		lebEncode(m_locals.at(_assignment.variableName));
  }
  
  bytes BinaryTransform::operator()(GlobalAssignment const& _assignment)
  {
  	return
  		std::visit(*this, *_assignment.value) +
  		toBytes(Opcode::GlobalSet) +
  		lebEncode(m_globalIDs.at(_assignment.variableName));
  }
  
  bytes BinaryTransform::operator()(If const& _if)
  {
  	bytes result =
  		std::visit(*this, *_if.condition) +
  		toBytes(Opcode::If) +
  		toBytes(ValueType::Void);
  
  	m_labels.emplace_back();
  
  	result += visit(_if.statements);
  	if (_if.elseStatements)
  		result += toBytes(Opcode::Else) + visit(*_if.elseStatements);
  
  	m_labels.pop_back();
  
  	result += toBytes(Opcode::End);
  	return result;
  }
  
  bytes BinaryTransform::operator()(Loop const& _loop)
  {
  	bytes result = toBytes(Opcode::Loop) + toBytes(ValueType::Void);
  
  	m_labels.emplace_back(_loop.labelName);
  	result += visit(_loop.statements);
  	m_labels.pop_back();
  
  	result += toBytes(Opcode::End);
  	return result;
  }
  
  bytes BinaryTransform::operator()(Branch const& _branch)
  {
  	return toBytes(Opcode::Br) + encodeLabelIdx(_branch.label.name);
  }
  
  bytes BinaryTransform::operator()(BranchIf const& _branchIf)
  {
  	bytes result = std::visit(*this, *_branchIf.condition);
  	result += toBytes(Opcode::BrIf) + encodeLabelIdx(_branchIf.label.name);
  	return result;
  }
  
  bytes BinaryTransform::operator()(Return const&)
  {
  	// Note that this does not work if the function returns a value.
  	return toBytes(Opcode::Return);
  }
  
  bytes BinaryTransform::operator()(Block const& _block)
  {
  	m_labels.emplace_back(_block.labelName);
  	bytes result =
  		toBytes(Opcode::Block) +
  		toBytes(ValueType::Void) +
  		visit(_block.statements) +
  		toBytes(Opcode::End);
  	m_labels.pop_back();
  	return result;
  }
  
  bytes BinaryTransform::operator()(FunctionDefinition const& _function)
  {
  	bytes ret;
  
  	vector<pair<size_t, ValueType>> localEntries = groupLocalVariables(_function.locals);
  	ret += lebEncode(localEntries.size());
  	for (pair<size_t, ValueType> const& entry: localEntries)
  	{
  		ret += lebEncode(entry.first);
  		ret += toBytes(entry.second);
  	}
  
  	m_locals.clear();
  	size_t varIdx = 0;
  	for (size_t i = 0; i < _function.parameters.size(); ++i)
  		m_locals[_function.parameters[i].name] = varIdx++;
  	for (size_t i = 0; i < _function.locals.size(); ++i)
  		m_locals[_function.locals[i].variableName] = varIdx++;
  
  	yulAssert(m_labels.empty(), "Stray labels.");
  
  	ret += visit(_function.body);
  	ret += toBytes(Opcode::End);
  
  	yulAssert(m_labels.empty(), "Stray labels.");
  
  	return prefixSize(move(ret));
  }
  
  BinaryTransform::Type BinaryTransform::typeOf(FunctionImport const& _import)
  {
  	return {
  		encodeTypes(_import.paramTypes),
  		encodeTypes(_import.returnType ? vector<wasm::Type>(1, *_import.returnType) : vector<wasm::Type>())
  	};
  }
  
  BinaryTransform::Type BinaryTransform::typeOf(FunctionDefinition const& _funDef)
  {
  	return {
  		encodeTypes(_funDef.parameters),
  		encodeTypes(_funDef.returnType ? vector<wasm::Type>(1, *_funDef.returnType) : vector<wasm::Type>())
  	};
  }
  
  uint8_t BinaryTransform::encodeType(wasm::Type _type)
  {
  	return uint8_t(toValueType(_type));
  }
  
  vector<uint8_t> BinaryTransform::encodeTypes(vector<wasm::Type> const& _types)
  {
  	vector<uint8_t> result;
  	for (wasm::Type t: _types)
  		result.emplace_back(encodeType(t));
  	return result;
  }
  
  vector<uint8_t> BinaryTransform::encodeTypes(wasm::TypedNameList const& _typedNameList)
  {
  	vector<uint8_t> result;
  	for (TypedName const& typedName: _typedNameList)
  		result.emplace_back(encodeType(typedName.type));
  	return result;
  }
  
  map<BinaryTransform::Type, vector<string>> BinaryTransform::typeToFunctionMap(
  	vector<wasm::FunctionImport> const& _imports,
  	vector<wasm::FunctionDefinition> const& _functions
  )
  {
  	map<Type, vector<string>> types;
  	for (auto const& import: _imports)
  		types[typeOf(import)].emplace_back(import.internalName);
  	for (auto const& fun: _functions)
  		types[typeOf(fun)].emplace_back(fun.name);
  
  	return types;
  }
  
  map<string, size_t> BinaryTransform::enumerateGlobals(Module const& _module)
  {
  	map<string, size_t> globals;
  	for (size_t i = 0; i < _module.globals.size(); ++i)
  		globals[_module.globals[i].variableName] = i;
  
  	return globals;
  }
  
  map<string, size_t> BinaryTransform::enumerateFunctions(Module const& _module)
  {
  	map<string, size_t> functions;
  	size_t funID = 0;
  	for (FunctionImport const& fun: _module.imports)
  		functions[fun.internalName] = funID++;
  	for (FunctionDefinition const& fun: _module.functions)
  		functions[fun.name] = funID++;
  
  	return functions;
  }
  
  map<string, size_t> BinaryTransform::enumerateFunctionTypes(map<Type, vector<string>> const& _typeToFunctionMap)
  {
  	map<string, size_t> functionTypes;
  	size_t typeID = 0;
  	for (vector<string> const& funNames: _typeToFunctionMap | boost::adaptors::map_values)
  	{
  		for (string const& name: funNames)
  			functionTypes[name] = typeID;
  		++typeID;
  	}
  
  	return functionTypes;
  }
  
  bytes BinaryTransform::typeSection(map<BinaryTransform::Type, vector<string>> const& _typeToFunctionMap)
  {
  	bytes result;
  	size_t index = 0;
  	for (Type const& type: _typeToFunctionMap | boost::adaptors::map_keys)
  	{
  		result += toBytes(ValueType::Function);
  		result += lebEncode(type.first.size()) + type.first;
  		result += lebEncode(type.second.size()) + type.second;
  
  		index++;
  	}
  
  	return makeSection(Section::TYPE, lebEncode(index) + move(result));
  }
  
  bytes BinaryTransform::importSection(
  	vector<FunctionImport> const& _imports,
  	map<string, size_t> const& _functionTypes
  )
  {
  	bytes result = lebEncode(_imports.size());
  	for (FunctionImport const& import: _imports)
  	{
  		uint8_t importKind = 0; // function
  		result +=
  			encodeName(import.module) +
  			encodeName(import.externalName) +
  			toBytes(importKind) +
  			lebEncode(_functionTypes.at(import.internalName));
  	}
  	return makeSection(Section::IMPORT, move(result));
  }
  
  bytes BinaryTransform::functionSection(
  	vector<FunctionDefinition> const& _functions,
  	map<string, size_t> const& _functionTypes
  )
  {
  	bytes result = lebEncode(_functions.size());
  	for (auto const& fun: _functions)
  		result += lebEncode(_functionTypes.at(fun.name));
  	return makeSection(Section::FUNCTION, move(result));
  }
  
  bytes BinaryTransform::memorySection()
  {
  	bytes result = lebEncode(1);
  	result.push_back(static_cast<uint8_t>(LimitsKind::Min));
  	result.push_back(1); // initial length
  	return makeSection(Section::MEMORY, move(result));
  }
  
  bytes BinaryTransform::globalSection(vector<wasm::GlobalVariableDeclaration> const& _globals)
  {
  	bytes result = lebEncode(_globals.size());
  	for (wasm::GlobalVariableDeclaration const& global: _globals)
  	{
  		ValueType globalType = toValueType(global.type);
  		result +=
  			toBytes(globalType) +
  			lebEncode(static_cast<uint8_t>(Mutability::Var)) +
  			toBytes(constOpcodeFor(globalType)) +
  			lebEncodeSigned(0) +
  			toBytes(Opcode::End);
  	}
  
  	return makeSection(Section::GLOBAL, move(result));
  }
  
  bytes BinaryTransform::exportSection(map<string, size_t> const& _functionIDs)
  {
  	bytes result = lebEncode(2);
  	result += encodeName("memory") + toBytes(Export::Memory) + lebEncode(0);
  	result += encodeName("main") + toBytes(Export::Function) + lebEncode(_functionIDs.at("main"));
  	return makeSection(Section::EXPORT, move(result));
  }
  
  bytes BinaryTransform::customSection(string const& _name, bytes _data)
  {
  	bytes result = encodeName(_name) + move(_data);
  	return makeSection(Section::CUSTOM, move(result));
  }
  
  bytes BinaryTransform::codeSection(vector<wasm::FunctionDefinition> const& _functions)
  {
  	bytes result = lebEncode(_functions.size());
  	for (FunctionDefinition const& fun: _functions)
  		result += (*this)(fun);
  	return makeSection(Section::CODE, move(result));
  }
  
  bytes BinaryTransform::visit(vector<Expression> const& _expressions)
  {
  	bytes result;
  	for (auto const& expr: _expressions)
  		result += std::visit(*this, expr);
  	return result;
  }
  
  bytes BinaryTransform::visitReversed(vector<Expression> const& _expressions)
  {
  	bytes result;
  	for (auto const& expr: _expressions | boost::adaptors::reversed)
  		result += std::visit(*this, expr);
  	return result;
  }
  
  bytes BinaryTransform::encodeLabelIdx(string const& _label) const
  {
  	yulAssert(!_label.empty(), "Empty label.");
  	size_t depth = 0;
  	for (string const& label: m_labels | boost::adaptors::reversed)
  		if (label == _label)
  			return lebEncode(depth);
  		else
  			++depth;
  	yulAssert(false, "Label not found.");
  }
  
  bytes BinaryTransform::encodeName(string const& _name)
  {
  	// UTF-8 is allowed here by the Wasm spec, but since all names here should stem from
  	// Solidity or Yul identifiers or similar, non-ascii characters ending up here
  	// is a very bad sign.
  	for (char c: _name)
  		yulAssert(uint8_t(c) <= 0x7f, "Non-ascii character found.");
  	return lebEncode(_name.size()) + asBytes(_name);
  }
  