1 files changed, 182 insertions, 0 deletions
diff --git a/src/js/wasm.js-post.js b/src/js/wasm.js-post.js
new file mode 100644
index 000000000..7f7ca9c1e
--- /dev/null
+++ b/src/js/wasm.js-post.js
@@ -0,0 +1,182 @@
+
+function integrateWasmJS(Module) {
+  // wasm.js has several methods for creating the compiled code module here:
+  //  * 'wasm-s-parser': load s-expression code from a .wast and create wasm
+  //  * 'asm2wasm': load asm.js code and translate to wasm
+  //  * 'just-asm': no wasm, just load the asm.js code and use that (good for testing)
+  // The method can be set at compile time (BINARYEN_METHOD), or runtime by setting Module['wasmJSMethod'].
+  var method = Module['wasmJSMethod'] || 'wasm-s-parser';
+  assert(method == 'asm2wasm' || method == 'wasm-s-parser' || method == 'just-asm');
+
+  if (method == 'just-asm') {
+    eval(Module['read'](Module['asmjsCodeFile']));
+    return;
+  }
+
+  var asm2wasmImports = { // special asm2wasm imports
+    "f64-rem": function(x, y) {
+      return x % y;
+    },
+    "f64-to-int": function(x) {
+      return x | 0;
+    },
+    "debugger": function() {
+      debugger;
+    },
+  };
+
+  function flatten(obj) {
+    var ret = {};
+    for (var x in obj) {
+      for (var y in obj[x]) {
+        if (ret[y]) Module['printErr']('warning: flatten dupe: ' + y);
+        ret[y] = obj[x][y];
+      }
+    }
+    return ret;
+  }
+
+  // wasm lacks globals, so asm2wasm maps them into locations in memory. that information cannot
+  // be present in the wasm output of asm2wasm, so we store it in a side file. If we load asm2wasm
+  // output, either generated ahead of time or on the client, we need to apply those mapped
+  // globals after loading the module.
+  function applyMappedGlobals() {
+    var mappedGlobals = JSON.parse(Module['read'](Module['wasmCodeFile'] + '.mappedGlobals'));
+    for (var name in mappedGlobals) {
+      var global = mappedGlobals[name];
+      if (!global.import) continue; // non-imports are initialized to zero in the typed array anyhow, so nothing to do here
+      var value = wasmJS['lookupImport'](global.module, global.base);
+      var address = global.address;
+      switch (global.type) {
+        case WasmTypes.i32: Module['HEAP32'][address >> 2] = value; break;
+        case WasmTypes.f32: Module['HEAPF32'][address >> 2] = value; break;
+        case WasmTypes.f64: Module['HEAPF64'][address >> 3] = value; break;
+        default: abort();
+      }
+    }
+  }
+
+  if (typeof WASM === 'object') {
+    // Provide an "asm.js function" for the application, called to "link" the asm.js module. We instantiate
+    // the wasm module at that time, and it receives imports and provides exports and so forth, the app
+    // doesn't need to care that it is wasm and not asm.
+    Module['asm'] = function(global, env, providedBuffer) {
+      // Load the wasm module
+      var binary = Module['readBinary'](Module['wasmCodeFile']);
+
+      // Create an instance of the module using native support in the JS engine.
+      var instance = WASM.instantiateModule(binary, flatten({ // XXX for now, flatten the imports
+        "global.Math": global.Math,
+        "env": env,
+        "asm2wasm": asm2wasmImports
+      }));
+
+      // The wasm instance creates its memory. But static init code might have written to
+      // buffer already, and we must copy it over.
+      // TODO: avoid this copy, by avoiding such static init writes
+      // TODO: in shorter term, just copy up to the last static init write
+      var oldBuffer = Module['buffer'];
+      var newBuffer = instance.memory;
+      assert(newBuffer.byteLength >= oldBuffer.byteLength, 'we might fail if we allocated more than TOTAL_MEMORY');
+      // the wasm module does write out the memory initialization, in range STATIC_BASE..STATIC_BUMP, so avoid that
+      (new Int8Array(newBuffer).subarray(0, STATIC_BASE)).set(new Int8Array(oldBuffer).subarray(0, STATIC_BASE));
+      (new Int8Array(newBuffer).subarray(STATIC_BASE + STATIC_BUMP)).set(new Int8Array(oldBuffer).subarray(STATIC_BASE + STATIC_BUMP));
+      updateGlobalBuffer(newBuffer);
+      updateGlobalBufferViews();
+      Module['reallocBuffer'] = function(size) {
+        var old = Module['buffer'];
+        wasmJS['asmExports']['__growWasmMemory'](size); // tiny wasm method that just does grow_memory
+        return Module['buffer'] !== old ? Module['buffer'] : null; // if it was reallocated, it changed
+      };
+
+      applyMappedGlobals();
+
+      return instance;
+    };
+
+    return;
+  }
+
+  var WasmTypes = {
+    none: 0,
+    i32: 1,
+    i64: 2,
+    f32: 3,
+    f64: 4
+  };
+
+  // Use wasm.js to polyfill and execute code in a wasm interpreter.
+  var wasmJS = WasmJS({});
+
+  // XXX don't be confused. Module here is in the outside program. wasmJS is the inner wasm-js.cpp.
+  wasmJS['outside'] = Module; // Inside wasm-js.cpp, Module['outside'] reaches the outside module.
+
+  // Information for the instance of the module.
+  var info = wasmJS['info'] = {
+    global: null,
+    env: null,
+    asm2wasm: asm2wasmImports,
+    parent: Module // Module inside wasm-js.cpp refers to wasm-js.cpp; this allows access to the outside program.
+  };
+
+  wasmJS['lookupImport'] = function(mod, base) {
+    var lookup = info;
+    if (mod.indexOf('.') < 0) {
+      lookup = (lookup || {})[mod];
+    } else {
+      var parts = mod.split('.');
+      lookup = (lookup || {})[parts[0]];
+      lookup = (lookup || {})[parts[1]];
+    }
+    lookup = (lookup || {})[base];
+    if (lookup === undefined) {
+      abort('bad lookupImport to (' + mod + ').' + base);
+    }
+    return lookup;
+  }
+
+  // The asm.js function, called to "link" the asm.js module. At that time, we are provided imports
+  // and respond with exports, and so forth.
+  Module['asm'] = function(global, env, providedBuffer) {
+    assert(providedBuffer === Module['buffer']); // we should not even need to pass it as a 3rd arg for wasm, but that's the asm.js way.
+
+    info.global = global;
+    info.env = env;
+
+    // wasm code would create its own buffer, at this time. But static init code might have
+    // written to the buffer already, and we must copy it over. We could just avoid
+    // this copy in wasm.js polyfilling, but to be as close as possible to real wasm,
+    // we do what wasm would do.
+    // TODO: avoid this copy, by avoiding such static init writes
+    // TODO: in shorter term, just copy up to the last static init write
+    var oldBuffer = Module['buffer'];
+    var newBuffer = new ArrayBuffer(oldBuffer.byteLength);
+    (new Int8Array(newBuffer)).set(new Int8Array(oldBuffer));
+    updateGlobalBuffer(newBuffer);
+    updateGlobalBufferViews();
+    wasmJS['providedTotalMemory'] = Module['buffer'].byteLength;
+
+    Module['reallocBuffer'] = function(size) {
+      var old = Module['buffer'];
+      wasmJS['asmExports']['__growWasmMemory'](size); // tiny wasm method that just does grow_memory
+      return Module['buffer'] !== old ? Module['buffer'] : null; // if it was reallocated, it changed
+    };
+
+    // Prepare to generate wasm, using either asm2wasm or wasm-s-parser
+    var code = Module['read'](method == 'asm2wasm' ? Module['asmjsCodeFile'] : Module['wasmCodeFile']);
+    var temp = wasmJS['_malloc'](code.length + 1);
+    wasmJS['writeAsciiToMemory'](code, temp);
+    if (method == 'asm2wasm') {
+      wasmJS['_load_asm2wasm'](temp);
+    } else {
+      wasmJS['_load_s_expr2wasm'](temp);
+      applyMappedGlobals();
+    }
+    wasmJS['_free'](temp);
+
+    wasmJS['_instantiate'](temp);
+
+    return wasmJS['asmExports'];
+  };
+}
+