Merge pull request #312 from WebAssembly/webidl

WebIDL bindings

1 files changed, 180 insertions, 0 deletions

diff --git a/src/shell-interface.h b/src/shell-interface.h
new file mode 100644
index 000000000..daaf23501
--- /dev/null
+++ b/src/shell-interface.h
@@ -0,0 +1,180 @@
+/*
+ * Copyright 2016 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.
+ */
+
+//
+// Implementation of the shell interpreter execution environment
+//
+
+#include "shared-constants.h"
+#include "wasm.h"
+#include "wasm-interpreter.h"
+
+namespace wasm {
+
+struct ExitException {};
+struct TrapException {};
+struct ParseException {};
+
+struct ShellExternalInterface : ModuleInstance::ExternalInterface {
+  // The underlying memory can be accessed through unaligned pointers which
+  // isn't well-behaved in C++. WebAssembly nonetheless expects it to behave
+  // properly. Avoid emitting unaligned load/store by checking for alignment
+  // explicitly, and performing memcpy if unaligned.
+  //
+  // The allocated memory tries to have the same alignment as the memory being
+  // simulated.
+  class Memory {
+    // Use char because it doesn't run afoul of aliasing rules.
+    std::vector<char> memory;
+    template <typename T>
+    static bool aligned(const char* address) {
+      static_assert(!(sizeof(T) & (sizeof(T) - 1)), "must be a power of 2");
+      return 0 == (reinterpret_cast<uintptr_t>(address) & (sizeof(T) - 1));
+    }
+    Memory(Memory&) = delete;
+    Memory& operator=(const Memory&) = delete;
+
+   public:
+    Memory() {}
+    void resize(size_t newSize) {
+      // Ensure the smallest allocation is large enough that most allocators
+      // will provide page-aligned storage. This hopefully allows the
+      // interpreter's memory to be as aligned as the memory being simulated,
+      // ensuring that the performance doesn't needlessly degrade.
+      //
+      // The code is optimistic this will work until WG21's p0035r0 happens.
+      const size_t minSize = 1 << 12;
+      size_t oldSize = memory.size();
+      memory.resize(std::max(minSize, newSize));
+      if (newSize < oldSize && newSize < minSize) {
+        std::memset(&memory[newSize], 0, minSize - newSize);
+      }
+    }
+    template <typename T>
+    void set(size_t address, T value) {
+      if (aligned<T>(&memory[address])) {
+        *reinterpret_cast<T*>(&memory[address]) = value;
+      } else {
+        std::memcpy(&memory[address], &value, sizeof(T));
+      }
+    }
+    template <typename T>
+    T get(size_t address) {
+      if (aligned<T>(&memory[address])) {
+        return *reinterpret_cast<T*>(&memory[address]);
+      } else {
+        T loaded;
+        std::memcpy(&loaded, &memory[address], sizeof(T));
+        return loaded;
+      }
+    }
+  } memory;
+
+  ShellExternalInterface() : memory() {}
+
+  void init(Module& wasm) override {
+    memory.resize(wasm.memory.initial * wasm::Memory::kPageSize);
+    // apply memory segments
+    for (auto segment : wasm.memory.segments) {
+      assert(segment.offset + segment.size <= wasm.memory.initial * wasm::Memory::kPageSize);
+      for (size_t i = 0; i != segment.size; ++i) {
+        memory.set(segment.offset + i, segment.data[i]);
+      }
+    }
+  }
+
+  Literal callImport(Import *import, ModuleInstance::LiteralList& arguments) override {
+    if (import->module == SPECTEST && import->base == PRINT) {
+      for (auto argument : arguments) {
+        std::cout << argument << '\n';
+      }
+      return Literal();
+    } else if (import->module == ENV && import->base == EXIT) {
+      // XXX hack for torture tests
+      std::cout << "exit()\n";
+      throw ExitException();
+    }
+    std::cout << "callImport " << import->name.str << "\n";
+    abort();
+  }
+
+  Literal load(Load* load, size_t addr) override {
+    switch (load->type) {
+      case i32: {
+        switch (load->bytes) {
+          case 1: return load->signed_ ? Literal((int32_t)memory.get<int8_t>(addr)) : Literal((int32_t)memory.get<uint8_t>(addr));
+          case 2: return load->signed_ ? Literal((int32_t)memory.get<int16_t>(addr)) : Literal((int32_t)memory.get<uint16_t>(addr));
+          case 4: return load->signed_ ? Literal((int32_t)memory.get<int32_t>(addr)) : Literal((int32_t)memory.get<uint32_t>(addr));
+          default: abort();
+        }
+        break;
+      }
+      case i64: {
+        switch (load->bytes) {
+          case 1: return load->signed_ ? Literal((int64_t)memory.get<int8_t>(addr)) : Literal((int64_t)memory.get<uint8_t>(addr));
+          case 2: return load->signed_ ? Literal((int64_t)memory.get<int16_t>(addr)) : Literal((int64_t)memory.get<uint16_t>(addr));
+          case 4: return load->signed_ ? Literal((int64_t)memory.get<int32_t>(addr)) : Literal((int64_t)memory.get<uint32_t>(addr));
+          case 8: return load->signed_ ? Literal((int64_t)memory.get<int64_t>(addr)) : Literal((int64_t)memory.get<uint64_t>(addr));
+          default: abort();
+        }
+        break;
+      }
+      case f32: return Literal(memory.get<float>(addr));
+      case f64: return Literal(memory.get<double>(addr));
+      default: abort();
+    }
+  }
+
+  void store(Store* store, size_t addr, Literal value) override {
+    switch (store->type) {
+      case i32: {
+        switch (store->bytes) {
+          case 1: memory.set<int8_t>(addr, value.geti32()); break;
+          case 2: memory.set<int16_t>(addr, value.geti32()); break;
+          case 4: memory.set<int32_t>(addr, value.geti32()); break;
+          default: abort();
+        }
+        break;
+      }
+      case i64: {
+        switch (store->bytes) {
+          case 1: memory.set<int8_t>(addr, (int8_t)value.geti64()); break;
+          case 2: memory.set<int16_t>(addr, (int16_t)value.geti64()); break;
+          case 4: memory.set<int32_t>(addr, (int32_t)value.geti64()); break;
+          case 8: memory.set<int64_t>(addr, value.geti64()); break;
+          default: abort();
+        }
+        break;
+      }
+      // write floats carefully, ensuring all bits reach memory
+      case f32: memory.set<int32_t>(addr, value.reinterpreti32()); break;
+      case f64: memory.set<int64_t>(addr, value.reinterpreti64()); break;
+      default: abort();
+    }
+  }
+
+  void growMemory(size_t /*oldSize*/, size_t newSize) override {
+    memory.resize(newSize);
+  }
+
+  void trap(const char* why) override {
+    std::cerr << "[trap " << why << "]\n";
+    throw TrapException();
+  }
+};
+
+}
+