Expose on/off heap agnostic Unsafe accessor methods

Motivation:
These are necessary for creating a buffer implementation that uses Unsafe, and works generically for both on-heap and off-heap memory.

Modification:
PlatformDependent previously forced clients to decide if they are working on on-heap memory, or off-heap memory, by giving accessors distinct APIs for each.
What is added here, are generic accessors that work the same in either case.

Result:
We can now make an Unsafe-based buffer implementation that is agnostic to whether the memory is on- or off-heap.

common/src/main/java/io/netty/util/internal/PlatformDependent.java

@@ -416,10 +416,34 @@ public final class PlatformDependent {
         return PlatformDependent0.getObject(object, fieldOffset);
     }
 
+    public static byte getByte(Object object, long fieldOffset) {
+        return PlatformDependent0.getByte(object, fieldOffset);
+    }
+
+    public static short getShort(Object object, long fieldOffset) {
+        return PlatformDependent0.getShort(object, fieldOffset);
+    }
+
+    public static char getChar(Object object, long fieldOffset) {
+        return PlatformDependent0.getChar(object, fieldOffset);
+    }
+
     public static int getInt(Object object, long fieldOffset) {
         return PlatformDependent0.getInt(object, fieldOffset);
     }
 
+    public static float getFloat(Object object, long fieldOffset) {
+        return PlatformDependent0.getFloat(object, fieldOffset);
+    }
+
+    public static long getLong(Object object, long fieldOffset) {
+        return PlatformDependent0.getLong(object, fieldOffset);
+    }
+
+    public static double getDouble(Object object, long fieldOffset) {
+        return PlatformDependent0.getDouble(object, fieldOffset);
+    }
+
     public static int getIntVolatile(long address) {
         return PlatformDependent0.getIntVolatile(address);
     }
@@ -592,6 +616,30 @@ public final class PlatformDependent {
         PlatformDependent0.putByte(data, offset, value);
     }
 
+    public static void putShort(Object data, int offset, short value) {
+        PlatformDependent0.putShort(data, offset, value);
+    }
+
+    public static void putChar(Object data, int offset, char value) {
+        PlatformDependent0.putChar(data, offset, value);
+    }
+
+    public static void putInt(Object data, int offset, int value) {
+        PlatformDependent0.putInt(data, offset, value);
+    }
+
+    public static void putFloat(Object data, int offset, float value) {
+        PlatformDependent0.putFloat(data, offset, value);
+    }
+
+    public static void putLong(Object data, int offset, long value) {
+        PlatformDependent0.putLong(data, offset, value);
+    }
+
+    public static void putDouble(Object data, int offset, double value) {
+        PlatformDependent0.putDouble(data, offset, value);
+    }
+
     public static void putShort(byte[] data, int index, short value) {
         PlatformDependent0.putShort(data, index, value);
     }
@@ -625,6 +673,10 @@ public final class PlatformDependent {
                                       dst, BYTE_ARRAY_BASE_OFFSET + dstIndex, length);
     }
 
+    public static void copyMemory(Object src, long srcOffset, Object dst, long dstOffset, long length) {
+        PlatformDependent0.copyMemory(src, srcOffset, dst, dstOffset, length);
+    }
+
     public static void copyMemory(long srcAddr, byte[] dst, int dstIndex, long length) {
         PlatformDependent0.copyMemory(null, srcAddr, dst, BYTE_ARRAY_BASE_OFFSET + dstIndex, length);
     }
@@ -633,6 +685,10 @@ public final class PlatformDependent {
         PlatformDependent0.setMemory(dst, BYTE_ARRAY_BASE_OFFSET + dstIndex, bytes, value);
     }
 
+    public static void setMemory(Object base, long offset, long length, byte value) {
+        PlatformDependent0.setMemory(base, offset, length, value);
+    }
+
     public static void setMemory(long address, long bytes, byte value) {
         PlatformDependent0.setMemory(address, bytes, value);
     }

common/src/main/java/io/netty/util/internal/PlatformDependent0.java

@@ -485,14 +485,34 @@ final class PlatformDependent0 {
         return UNSAFE.getObject(object, fieldOffset);
     }
 
+    static byte getByte(Object object, long fieldOffset) {
+        return UNSAFE.getByte(object, fieldOffset);
+    }
+
+    static short getShort(Object object, long fieldOffset) {
+        return UNSAFE.getShort(object, fieldOffset);
+    }
+
+    static char getChar(Object object, long fieldOffset) {
+        return UNSAFE.getChar(object, fieldOffset);
+    }
+
     static int getInt(Object object, long fieldOffset) {
         return UNSAFE.getInt(object, fieldOffset);
     }
 
-    private static long getLong(Object object, long fieldOffset) {
+    static float getFloat(Object object, long fieldOffset) {
+        return UNSAFE.getFloat(object, fieldOffset);
+    }
+
+    static long getLong(Object object, long fieldOffset) {
         return UNSAFE.getLong(object, fieldOffset);
     }
 
+    static double getDouble(Object object, long fieldOffset) {
+        return UNSAFE.getDouble(object, fieldOffset);
+    }
+
     static long objectFieldOffset(Field field) {
         return UNSAFE.objectFieldOffset(field);
     }
@@ -577,14 +597,38 @@ final class PlatformDependent0 {
         UNSAFE.putShort(data, BYTE_ARRAY_BASE_OFFSET + index, value);
     }
 
+    static void putShort(Object data, long offset, short value) {
+        UNSAFE.putShort(data, offset, value);
+    }
+
+    static void putChar(Object data, long offset, char value) {
+        UNSAFE.putChar(data, offset, value);
+    }
+
     static void putInt(byte[] data, int index, int value) {
         UNSAFE.putInt(data, BYTE_ARRAY_BASE_OFFSET + index, value);
     }
 
+    static void putInt(Object data, long offset, int value) {
+        UNSAFE.putInt(data, offset, value);
+    }
+
+    static void putFloat(Object data, long offset, float value) {
+        UNSAFE.putFloat(data, offset, value);
+    }
+
     static void putLong(byte[] data, int index, long value) {
         UNSAFE.putLong(data, BYTE_ARRAY_BASE_OFFSET + index, value);
     }
 
+    static void putLong(Object data, long offset, long value) {
+        UNSAFE.putLong(data, offset, value);
+    }
+
+    static void putDouble(Object data, long offset, double value) {
+        UNSAFE.putDouble(data, offset, value);
+    }
+
     static void putObject(Object o, long offset, Object x) {
         UNSAFE.putObject(o, offset, x);
     }