From 2c6fb9aae09af48e0a35e37ce7ba0fc07d042712 Mon Sep 17 00:00:00 2001
From: Volker <Volker@Volker.fritz.box>
Date: Mon, 13 Aug 2018 17:39:14 +0200
Subject: [PATCH] Add handling of global section.

---
 .../binary/BinaryModuleWriter.java            | 40 +++++++++++++++++++
 .../jwebassembly/binary/Global.java           | 30 ++++++++++++++
 2 files changed, 70 insertions(+)
 create mode 100644 src/de/inetsoftware/jwebassembly/binary/Global.java

diff --git a/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java b/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java
index 8326545..4c4cc7a 100644
--- a/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java
+++ b/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java
@@ -55,6 +55,8 @@ public class BinaryModuleWriter extends ModuleWriter implements InstructionOpcod
 
     private Map<String, Function>       functions           = new LinkedHashMap<>();
 
+    private Map<String, Global>         globals             = new LinkedHashMap<>();
+
     private Map<String, String>         exports             = new LinkedHashMap<>();
 
     private Map<String, ImportFunction> imports             = new LinkedHashMap<>();
@@ -86,6 +88,7 @@ public class BinaryModuleWriter extends ModuleWriter implements InstructionOpcod
         writeTypeSection();
         writeImportSection();
         writeFunctionSection();
+        writeGlobalSection();
         writeExportSection();
         writeCodeSection();
 
@@ -163,6 +166,27 @@ public class BinaryModuleWriter extends ModuleWriter implements InstructionOpcod
         }
     }
 
+    /**
+     * Write the global section to the output. This section contains a declaring of global (static) variables.
+     * 
+     * @throws IOException
+     *             if any I/O error occur
+     */
+    private void writeGlobalSection() throws IOException {
+        int count = globals.size();
+        if( count > 0 ) {
+            WasmOutputStream stream = new WasmOutputStream();
+            stream.writeVaruint32( count );
+            for( Global var : globals.values() ) {
+                stream.write( var.type.getCode() );
+                stream.write( var.mutability ? 1 : 0 );
+                writeConst( stream, 0, var.type );
+                stream.writeOpCode( END );
+            }
+            wasm.writeSection( SectionType.Global, stream, null );
+        }
+    }
+
     /**
      * Write the export section to the output. This section contains a mapping from the external index to the type signature index.
      * 
@@ -307,6 +331,22 @@ public class BinaryModuleWriter extends ModuleWriter implements InstructionOpcod
      */
     @Override
     protected void writeConst( Number value, ValueType valueType ) throws IOException {
+        writeConst( codeStream, value, valueType );
+    }
+
+    /**
+     * Write a constant number value
+     * 
+     * @param codeStream
+     *            the target stream
+     * @param value
+     *            the value
+     * @param valueType
+     *            the data type of the number
+     * @throws IOException
+     *             if any I/O error occur
+     */
+    private static void writeConst( WasmOutputStream codeStream, Number value, ValueType valueType ) throws IOException {
         switch( valueType ) {
             case i32:
                 codeStream.writeOpCode( I32_CONST );
diff --git a/src/de/inetsoftware/jwebassembly/binary/Global.java b/src/de/inetsoftware/jwebassembly/binary/Global.java
new file mode 100644
index 0000000..4835bd2
--- /dev/null
+++ b/src/de/inetsoftware/jwebassembly/binary/Global.java
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2018 Volker Berlin (i-net software)
+ *
+ * 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.
+ */
+package de.inetsoftware.jwebassembly.binary;
+
+import de.inetsoftware.jwebassembly.module.ValueType;
+
+/**
+ * An entry in the global section of the WebAssembly.
+ * 
+ * @author Volker Berlin
+ */
+class Global {
+
+    ValueType type;
+
+    boolean mutability;
+}