samples and html fix

runner/build.sh

@@ -3,4 +3,13 @@
 # "Compile rust source and put it as a tested contract"
 
 mkdir -p out
-rustc $1 -o out/contract.js -O --target wasm32-unknown-emscripten
+
+file=$1
+if [ ${file: -3} == ".rs" ]
+then
+    # Rust is compiled with rustc
+    rustc $file -o out/contract.js -O --target wasm32-unknown-emscripten
+else
+    # c/c++ can be compiled directly by emcc
+    emcc $file -Os -s WASM=1 -s SIDE_MODULE=1 -o out/contract.wasm
+fi

runner/index.html

@@ -35,7 +35,7 @@
 
           env.DYNAMICTOP_PTR = env.DYNAMICTOP_PTR || 0;
           env.STACKTOP = env.STACKTOP || 0;
-          env.STACK_MAX = env.STACK_MAX || 0;
+          env.STACK_MAX = env.STACK_MAX || 5*1024*1024;
           env.enlargeMemory = env.enlargeMemory || function() { throw "error enlarging memory"; };
           env.getTotalMemory = env.getTotalMemory || function() { return 65536 * 256; };
           env.abortOnCannotGrowMemory = env.abortOnCannotGrowMemory || function() { throw "abort growing memory"; };
@@ -45,10 +45,10 @@
           env.tableBase = env.tableBase || 0;
 
           if (!imports.env.memory) {
-            imports.env.memory = new WebAssembly.Memory({ initial: 256 });
+            imports.env.memory = new WebAssembly.Memory({ initial: 256, maximum: 256 });
           }
           if (!imports.env.table) {
-            imports.env.table = new WebAssembly.Table({ initial: 0, element: 'anyfunc' });
+            imports.env.table = new WebAssembly.Table({ initial: 0, maximum: 0, element: 'anyfunc' });
           }
           return new WebAssembly.Instance(module, imports);
         });

samples/hello_world.c

@@ -0,0 +1,3 @@
+int call(int x) {
+  return 2 * x;
+}