src/tools/wasm2c/wasm2c-builder.cpp

/*
 * Copyright 2026 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.
 */

#include <iostream>
#include <string>

#include "tools/wasm2c/c-printer.h"
#include "tools/wasm2c/wasm2c-builder.h"
#include "wasm.h"

// code to be inserted into the generated output
extern const char* HeaderTop;
extern const char* HeaderBottom;
extern const char* SourceIncludes;
extern const char* SourceDeclarations;

namespace wasm {

namespace {

std::string mangleName(const std::string& name) {
  if (name.empty()) {
    return "";
  }
  std::string result;
  bool isFirst = true;
  for (char c : name) {
    if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
        (c >= '0' && c <= '9')) {
      result += c;
      isFirst = false;
    } else if (c == '_') {
      if (isFirst) {
        result += "0x5F";
        isFirst = false;
      } else {
        result += '_';
      }
    } else {
      char buf[8];
      snprintf(buf, sizeof(buf), "0x%02X", (unsigned char)c);
      result += buf;
      isFirst = false;
    }
  }
  return result;
}

} // anonymous namespace

void Wasm2CBuilder::processWasm(Module* wasm,
                                std::ostream& cOut,
                                std::ostream& hOut) {
  this->module = wasm;
  std::string moduleName =
    flags.moduleName.empty() ? "test" : mangleName(flags.moduleName);
  std::string guardName = "WASM_H_GENERATED_" + moduleName;
  std::transform(
    guardName.begin(), guardName.end(), guardName.begin(), ::toupper);

  CPrinter h(hOut);
  CPrinter c(cOut);

  // Header file prefix
  h << "/* Automatically generated by wasm2c */" << endl;
  h << "#ifndef " << guardName << endl;
  h << "#define " << guardName << endl << endl;
  h << "#include \"wasm-rt.h\"" << endl << endl;
  h << HeaderTop << endl;

  // Source file prefix
  c << "/* Automatically generated by wasm2c */" << endl;
  c << SourceIncludes << endl;
  if (!flags.headerName.empty()) {
    c << "#include \"" << flags.headerName << "\"" << endl;
  } else {
    c << "#include \"wasm.h\"" << endl;
  }
  c << SourceDeclarations << endl;

  // Structure context definition
  h << "typedef struct w2c_" << moduleName << " {" << endl;
  h.indent();
  h << "char dummy_member;" << endl;
  h.outdent();
  h << "} w2c_" << moduleName << ";" << endl << endl;

  // Lifecycle signatures in header
  h << "void wasm2c_" << moduleName << "_instantiate(w2c_" << moduleName << "*";
  h << ");" << endl;
  h << "void wasm2c_" << moduleName << "_free(w2c_" << moduleName << "*);"
    << endl;
  h << "wasm_rt_func_type_t wasm2c_" << moduleName
    << "_get_func_type(uint32_t param_count, uint32_t result_count, ...);"
    << endl;

  // Instantiate hooks
  c << "void wasm2c_" << moduleName << "_instantiate(w2c_" << moduleName
    << "* instance";
  c << ") {" << endl;
  c.indent();
  c << "assert(wasm_rt_is_initialized());" << endl;
  c.outdent();
  c << "}" << endl << endl;

  // Free hooks
  c << "void wasm2c_" << moduleName << "_free(w2c_" << moduleName
    << "* instance) {" << endl;
  c << "}" << endl << endl;

  // Signature match ladders
  c << "wasm_rt_func_type_t wasm2c_" << moduleName
    << "_get_func_type(uint32_t param_count, uint32_t result_count, ...) {"
    << endl;
  c.indent();
  c << "va_list args;" << endl << endl;

  c << "return NULL;" << endl;
  c.outdent();
  c << "}" << endl << endl;

  // Header file suffix
  h << endl;
  h << HeaderBottom << endl;
  h << "#endif  /* " << guardName << " */" << endl;
}

} // namespace wasm