NativeInt8.java

/*
** Module   : NativeInt8.java
** Abstract : descriptor for a unsigned or signed byte 
**
** Copyright (c) 2013-2017, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------Description---------------------------------
** 001 GES 20140109 First version, which defaults to being an unsigned byte.
** 002 GES 20140212 Non-scalar instances must emit as a sign-extended value of the platform's
**                  word-size instead of the actual size of the instance. Also fixed the sign
**                  processing such that a negative value will report as a signed byte. This is
**                  critical to getting the proper sign-extending behavior at the native layer. 
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 of the
** License, or (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
** GNU Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
** 
** Additional terms under GNU Affero GPL version 3 section 7:
** 
**   Under Section 7 of the GNU Affero GPL version 3, the following additional
**   terms apply to the works covered under the License.  These additional terms
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** 
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** 
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*/

package com.goldencode.p2j.library;

import java.io.*;
import com.goldencode.p2j.util.*;

/**
 * A descriptor for a byte which may be either signed or unsigned. The 4GL does not differentiate
 * between the two types, but the native code may be sensitive to this.  The type will be
 * as {@link LibraryManager#TYPE_SIGNED_INT8} if the value is negative and otherwise it will
 * report as {@link LibraryManager#TYPE_UNSIGNED_INT8}.
 */
public class NativeInt8 
extends NativeInteger
{
   /**
    * Default constructor.
    */
   public NativeInt8()
   {
      super();
      
      // default to unsigned and override later if needed 
      type = LibraryManager.TYPE_UNSIGNED_INT8;
   }
   
   /**
    * Assign the data element.
    *
    * @param    value
    *           The new integer data element.
    */
   public void setValue(long value)
   {
      super.setValue(value);
      
      // override the sign
      type = (value < 0) ? LibraryManager.TYPE_SIGNED_INT8 : LibraryManager.TYPE_UNSIGNED_INT8;
   }
   
   /**
    * Report the size (in bytes) of the native memory needed to store this instance.
    * <p>
    * This should never be called on the server, only on the client side.
    *
    * @return   The number of bytes needed.
    */
   public int size()
   {
      return isInArray() ? 1 : LibraryManager.ptrSize();
   }
   
   /**
    * Worker method to read the primitive value from the first index position of the given
    * memory buffer.
    *
    * @param    ptr
    *           The memory buffer to reference.
    */
   protected void readNative(memptr ptr)
   {
      integer num = ptr.getByte(1);
      
      if (!num.isUnknown())
      {
         value = num.longValue();
      }
   }
   
   /**
    * Worker method to write the primitive value to the first index position of the given
    * memory buffer.
    *
    * @param    ptr
    *           The memory buffer to reference.
    */
   protected void writeNative(memptr ptr)
   {
      if (isInArray())
      {
         ptr.setByte(value, 1);
      }
      else
      {
         writeNativeWordSize(ptr);
      }
   }
}