From f40173a7f6eb47140edb473a80617241ba869c83 Mon Sep 17 00:00:00 2001
From: Volker Berlin <volker.berlin@googlemail.com>
Date: Sun, 20 Sep 2020 14:00:41 +0200
Subject: [PATCH] Replacement for Array.getLength(x)

---
 .../nativecode/ReplacementForArray.java       | 132 ++++++++++++++++++
 1 file changed, 132 insertions(+)
 create mode 100644 src/de/inetsoftware/jwebassembly/module/nativecode/ReplacementForArray.java

diff --git a/src/de/inetsoftware/jwebassembly/module/nativecode/ReplacementForArray.java b/src/de/inetsoftware/jwebassembly/module/nativecode/ReplacementForArray.java
new file mode 100644
index 0000000..23cd958
--- /dev/null
+++ b/src/de/inetsoftware/jwebassembly/module/nativecode/ReplacementForArray.java
@@ -0,0 +1,132 @@
+/*
+   Copyright 2020 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.module.nativecode;
+
+import de.inetsoftware.jwebassembly.api.annotation.Replace;
+import de.inetsoftware.jwebassembly.api.annotation.WasmTextCode;
+
+import static de.inetsoftware.jwebassembly.module.TypeManager.*;
+
+/**
+ * Replacement for java.lang.reflect.Array
+ *
+ * @author Volker Berlin
+ */
+public class ReplacementForArray {
+
+    /**
+     * get the vtable value
+     * 
+     * @param obj
+     *            the instance
+     * @return the vtable value
+     */
+    @WasmTextCode( "local.get 0 " // THIS
+                    + "struct.get java/lang/Object .vtable " // vtable is on index 0
+                    + "return " //
+    )
+    private static native int getVTable( Object obj );
+
+    /**
+     * WASM code
+     * <p>
+     * Load an i32 from memory. The offset must be aligned. Should be inlined from the optimizer.
+     * 
+     * @param pos
+     *            the memory position
+     * @return the value from the memory
+     */
+    @WasmTextCode( "local.get 0 " + //
+                    "i32.load offset=0 align=4 " + //
+                    "return" )
+    private static native int getIntFromMemory( int pos );
+
+    /**
+     * Replacement of the native Java methods Array.getLength(x)
+     * 
+     * @param obj
+     *            the object
+     * @return the length of the object
+     */
+    @Replace( "java/lang/reflect/Array.getLength(Ljava/lang/Object;)I" )
+    private static int array_getLength( Object obj ) {
+        int vtable = getVTable( obj );
+        int componentType = getIntFromMemory( vtable + TYPE_DESCRIPTION_ARRAY_TYPE );
+        switch( componentType ) {
+            case -1:
+                throw new java.lang.IllegalArgumentException( "Argument is not an array" );
+            case BOOLEAN:
+                return getLengthOfBooleans( obj );
+            case BYTE:
+                return getLengthOfBytes( obj );
+            case CHAR:
+                return getLengthOfChars( obj );
+            case DOUBLE:
+                return getLengthOfDoubles( obj );
+            case FLOAT:
+                return getLengthOfFloats( obj );
+            case INT:
+                return getLengthOfInts( obj );
+            case LONG:
+                return getLengthOfLongs( obj );
+            case SHORT:
+                return getLengthOfShorts( obj );
+            default:
+                return ((Object[])obj).length;
+        }
+    }
+
+    @WasmTextCode( "local.get 0 " // THIS
+                    + "array.len [Z " //
+                    + "return " )
+    private static native int getLengthOfBooleans( Object obj );
+
+    @WasmTextCode( "local.get 0 " // THIS
+                    + "array.len [B " //
+                    + "return " )
+    private static native int getLengthOfBytes( Object obj );
+
+    @WasmTextCode( "local.get 0 " // THIS
+                    + "array.len [C " //
+                    + "return " )
+    private static native int getLengthOfChars( Object obj );
+
+    @WasmTextCode( "local.get 0 " // THIS
+                    + "array.len [D " //
+                    + "return " )
+    private static native int getLengthOfDoubles( Object obj );
+
+    @WasmTextCode( "local.get 0 " // THIS
+                    + "array.len [F " //
+                    + "return " )
+    private static native int getLengthOfFloats( Object obj );
+
+    @WasmTextCode( "local.get 0 " // THIS
+                    + "array.len [I " //
+                    + "return " )
+    private static native int getLengthOfInts( Object obj );
+
+    @WasmTextCode( "local.get 0 " // THIS
+                    + "array.len [J " //
+                    + "return " )
+    private static native int getLengthOfLongs( Object obj );
+
+    @WasmTextCode( "local.get 0 " // THIS
+                    + "array.len [S " //
+                    + "return " )
+    private static native int getLengthOfShorts( Object obj );
+}