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/*
* Copyright 2015 WebAssembly Community Group participants
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
//
// Parses and emits WebAssembly binary code
//
#ifndef wasm_wasm_binary_h
#define wasm_wasm_binary_h
#include <ostream>
#include "wasm.h"
#include "shared-constants.h"
namespace wasm {
enum Section {
Memory = 0,
Signatures = 1,
Functions = 2,
DataSegments = 4,
FunctionTable = 5,
End = 6
};
enum FunctionEntry {
Named = 1,
Import = 2,
Locals = 4,
Export = 8
};
char binaryWasmType(WasmType type) {
switch (type) {
case none: return 0;
case i32: return 1;
case i64: return 2;
case f32: return 3;
case f64: return 4;
default: abort();
}
}
class WasmBinaryWriter : public WasmVisitor<void> {
Module* wasm;
ostream& o;
public:
WasmBinaryWriter(Module* wasm, ostream& o) : wasm(wasm), o(o) {}
void write() {
writeMemory();
writeSignatures();
writeFunctions();
writeDataSegments();
writeFunctionTable();
writeEnd();
}
writeMemory() {
o << Section::Memory << char(log2(wasm.memory.initial)) <<
char(log2(wasm.memory.max)) <<
char(1); // export memory
}
writeSignatures() {
o << Section::Signatures << LEB128(wasm.functionTypes.size());
for (auto type : wasm.functionTypes) {
o << char(type->params.size());
o << binaryWasmType(type->result);
for (auto param : type->params) {
o << binaryWasmType(param);
}
}
}
int16_t functionTypeIndex(Name type) {
// TODO: optimize
for (size_t i = 0; i < wasm.functionTypes.size(); i++) {
if (wasm.functionTypes[i].name == type) return i;
}
abort();
}
std::map<Name, size_t> mappedLocals; // local name => index in compact form of [all int32s][all int64s]etc
std::map<WasmType, size_t> numLocalsByType; // type => number of locals of that type in the compact form
void mapLocals(Function* function) {
for (auto& local : function->locals) {
numLocalsByType[local.type]++;
}
std::map<WasmType, size_t> currLocalsByType;
for (auto& local : function->locals) {
size_t index = 0;
Name name = local.name;
WasmType type = local.type;
currLocalsByType[type]++; // increment now for simplicity, must decremebt it in returns
if (type == i32) {
mappedLocals[name] = index + currLocalsByType[i32] - 1;
break;
}
index += numLocalsByType[i32];
if (type == i64) {
mappedLocals[name] = index + currLocalsByType[i64] - 1;
break;
}
index += numLocalsByType[i64];
if (type == f32) {
mappedLocals[name] = index + currLocalsByType[f32] - 1;
break;
}
index += numLocalsByType[f32];
if (type == f64) {
mappedLocals[name] = index + currLocalsByType[f64] - 1;
break;
}
}
}
std::vector<char> encodeAST(Function* function) {
}
writeFunctions() {
size_t total = wasm.imports.size() + wasm.functions.size();
o << Section::Functions << LEB128(total);
for (size_t i = 0; i < total; i++) {
Import* import = i < wasm.imports.size() ? wasm.imports[i] : nullptr;
Function* function = i >= wasm.imports.size() ? wasm.functions[i - wasm.imports.size()] : nullptr;
Name name, type;
if (import) {
name = import->name;
type = import->type.name;
} else {
name = function->name;
type = function->type;
}
o << functionTypeIndex(type);
o << char(FunctionEntry::Named |
(FunctionEntry::Import * !!import) |
(FunctionEntry::Locals * (function && function->locals.size() > 0) |
(FunctionEntry::Export) * (wasm.exportsMap[name].count(name) > 0)));
// TODO: name. how can we do an offset? into what section? and how do we know it now?
if (function && function->locals.size() > 0) {
mapLocals(function);
o << uint16_t(numLocalsByType[i32])
<< uint16_t(numLocalsByType[i64])
<< uint16_t(numLocalsByType[f32])
<< uint16_t(numLocalsByType[f64]);
}
if (function) {
auto ast = encodeAST(function);
o << uint16_t(ast.size());
for (auto c : ast) {
o << c;
}
}
}
}
writeDataSegments() {
}
writeFunctionTable() {
}
writeEnd() {
o << Section::End;
}
};
class WasmBinaryBuilder {
AllocatingModule& wasm;
MixedArena& allocator;
istream& i;
public:
WasmBinaryBuilder(AllocatingModule& wasm, istream& i) : wasm(wasm), allocator(wasm.allocator), i(i) {}
void read() {
//
}
};
} // namespace wasm
#endif // wasm_wasm_binary_h
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