UTF8-> char[] support

Author: Horcrux7

src/de/inetsoftware/jwebassembly/api/java/lang/ReplacementForStringCoding.java

@@ -0,0 +1,58 @@
+/*
+ * 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.api.java.lang;
+
+import java.util.Arrays;
+
+import de.inetsoftware.jwebassembly.api.annotation.Replace;
+
+/**
+ * Replacement methods for the class java.lang.StringCoding.
+ * 
+ * @author Volker Berlin
+ */
+public class ReplacementForStringCoding {
+
+    /**
+     * Replacement for StringCoding.decode(byte[] ba, int off, int len) in Java 8. Decode UTF8 bytes to unicode 16 chars.
+     */
+    @Replace( "java/lang/StringCoding.decode([BII)[C" )
+    private static char[] decode(byte[] bytes, int offset, int length) {
+        int count = 0;
+        char[] buffer = new char[length - offset];
+        while( offset < length ) {
+            int ch = bytes[offset++] & 0xFF;
+
+            if( ch <= 0x7F ) {
+                //ch = ch;
+            } else if( ch <= 0xDF ) {
+                ch = ((ch & 0x1F) << 6) | (bytes[offset++] & 0x3F);
+            } else if( ch <= 0xEF ) {
+                ch = ((ch & 0x0F) << 12) | ((bytes[offset++] & 0x3F) << 6) | (bytes[offset++] & 0x3F);
+            } else {
+                ch = ((ch & 0x07) << 18) | ((bytes[offset++] & 0x3F) << 12) | ((bytes[offset++] & 0x3F) << 6) | (bytes[offset++] & 0x3F);
+                // high surrogate
+                buffer[count++] = (char)(0xD7C0 + ((ch >> 10) & 0x3ff));
+                // low surrogate
+                ch = 0xDC00 + (ch & 0x3ff);
+            }
+
+            buffer[count++] = (char)ch;
+        }
+
+        return count == length ? buffer : Arrays.copyOf( buffer, count );
+    }
+}