# NativePrimitive.java

    /*
    ** Module   : NativePrimitive.java
    ** Abstract : descriptor base class for scalar data as an argument or return value to a native
    **            function
    **
    ** Copyright (c) 2013-2017, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- ---------------------------------Description---------------------------------
    ** 001 GES 20131212 First version.
    */
    /*
    ** 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
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
    **     of Golden Code Development Corporation. You are not authorized to use the
    **     name Golden Code, FWD, or the names of any author or contributor, for
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    **     the covered work, without written authorization.
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    **
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    **     versions of the covered work must be marked in a reasonable way to make it
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    **     Corporation or FWD.  All modified versions must contain the notices of
    **     attribution required in this license.
    */

    package com.goldencode.p2j.library;

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

    /**
     * A descriptor base class for scalar data as an argument or return value to a native function.
     */
    public abstract class NativePrimitive
    extends BaseNativeType
    {
       /**
        * Default constructor.
        */
       public NativePrimitive()
       {
       }

       /**
        * Render the data into native memory, which will be allocated if the address is not
        * given.
        * <p>
        * This should never be called on the server, only on the client side.
        *
        * @param    addr
        *           The memory address to which the data should be rendered, if the caller
        *           is supplying a buffer or 0 if the buffer should be allocated.
        *
        * @return   The memory address of the rendered data or 0 if there is no data to
        *           output.
        */
       public long render(long addr)
       {
          int sz = size();

          memptr local = new memptr();

          if (addr == 0)
          {
             // save off for restore use later
             ref = local;

             // allocate the block which must be big enough to store the data
             local.setLength(sz);

             addr = local.getPointerValue().longValue();
          }
          else
          {
             local.setPointerValue(addr);
          }

          if (copyIn)
          {
             writeNative(local);
          }

          return addr;
       }

       /**
        * Copy back (if necessary) data from the native memory and deallocate the memory
        * if this instance allocated it in the first place.
        * <p>
        * This should never be called on the server, only on the client side.
        *
        * @param    addr
        *           The memory address from which the data should be restored, if the caller
        *           is supplying a buffer or 0 if the buffer should already exist.
        */
       public void restore(long addr)
       {
          memptr local = ref;

          if (local == null && addr != 0)
          {
             local = new memptr();
             local.setPointerValue(addr);
          }

          if (copyOut && local != null)
          {
             readNative(local);
          }

          // deallocate memory if we allocated it
          if (ref != null)
             ref.setLength(0);
       }

       /**
        * 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 abstract void readNative(memptr ptr);

       /**
        * 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 abstract void writeNative(memptr ptr);
    }