# BaseNativeType.java

    /*
    ** Module   : BaseNativeType.java
    ** Abstract : descriptor for a native function's argument or return value
    **
    ** Copyright (c) 2013-2017, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- ---------------------------------Description---------------------------------
    ** 001 GES 20131211 First version.
    ** 002 GES 20140127 Fixed out of order memory buffer delete in restore().
    */
    /*
    ** 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.
    **
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    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
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    **     the covered work, without written authorization.
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    */

    package com.goldencode.p2j.library;

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

    /**
     * Descriptor for a native function's argument or return value.
     */
    public abstract class BaseNativeType
    implements Externalizable
    {
       /** Flag to control whether this element should be copied TO the native function. */
       protected boolean copyIn = false;

       /** Flag to control whether this element should be copied BACK FROM the native function. */
       protected boolean copyOut = false;

       /** Flag to control whether this element should be passed as a pointer. */
       protected boolean passByPointer = false;

       /** Data type of the instance (defined as a {@link LibraryManager} constant). */
       protected int type = -1;

       /** On the client side, this is used to render the data into native memory. */
       protected memptr ref = null;

       /** On the client side, this is used to render the data as a pointer. */
       protected memptr ptr = null;

       /**
        * Default constructor.
        */
       public BaseNativeType()
       {
       }

       /**
        * Reports whether this element should be copied TO the native function.
        *
        * @return   <code>true</code> for INPUT and INPUT-OUTPUT parameters, <code>false</code>
        *           otherwise.
        */
       public boolean isCopyIn()
       {
          return copyIn;
       }

       /**
        * Assigns the flag for whether this element should be copied TO the native function.
        *
        * @param    copyIn
        *           <code>true</code> for INPUT and INPUT-OUTPUT parameters, <code>false</code>
        *           otherwise.
        */
       public void setCopyIn(boolean copyIn)
       {
          this.copyIn = copyIn;
       }

       /**
        * Reports whether this element should be copied BACK FROM the native function.
        *
        * @return   <code>true</code> for OUTPUT and RETURN parameters, <code>false</code>
        *           otherwise.
        */
       public boolean isCopyOut()
       {
          return copyOut;
       }

       /**
        * Assigns the flag for whether this element should be copied BACK FROM the native function.
        *
        * @param    copyOut
        *           <code>true</code> for OUTPUT and RETURN parameters, <code>false</code>
        *           otherwise.
        */
       public void setCopyOut(boolean copyOut)
       {
          this.copyOut = copyOut;
       }

       /**
        * Reports whether the argument passed should be a pointer to the data element or whether the
        * data should be passed by value to the native function.
        *
        * @return   The stored value of the flag.
        */
       public boolean isPassByPointer()
       {
          return passByPointer;
       }

       /**
        * Assigns the flag for whether the argument passed should be a pointer to the data element or
        * whether the data should be passed by value to the native function.
        *
        * @param    passByPointer
        *           The new value of the flag.
        */
       public void setPassByPointer(boolean passByPointer)
       {
          this.passByPointer = passByPointer;
       }

       /**
        * Allocate native memory and render the data into that memory. If the instance requires
        * copying data back from native memory or must be forced into passing by pointer, then
        * this method will return back the address that contains the address of the memory in
        * which the data is rendered.
        * <p>
        * This should never be called on the server, only on the client side.
        *
        * @return   The memory address of the rendered data or 0 if there is no data to
        *           output.
        */
       public long render()
       {
          long addr = render(0);

          if (copyOut || passByPointer)
          {
             int sz = LibraryManager.ptrSize();

             ptr = new memptr();
             ptr.setLength(sz);

             if (sz == 4)
             {
                ptr.setLong(addr, 1);
             }
             else
             {
                ptr.setInt64(addr, 1);
             }

             addr = ptr.getPointerValue().longValue();
          }

          return addr;
       }

       /**
        * Copy back (if necessary) data from the native memory and deallocate the memory.
        * <p>
        * This should never be called on the server, only on the client side.
        */
       public void restore()
       {
          long addr = 0;

          if (ptr != null)
          {
             addr = ptr.getPointerValue().longValue();
          }

          restore(addr);

          if (ptr != null)
          {
             ptr.setLength(0);
             ptr = null;
          }
       }

       /**
        * Manually override the data type of the instance.
        *
        * @param    type
        *           A {@link LibraryManager} constant representing the data type.
        */
       public void setType(int type)
       {
          this.type = type;
       }

       /**
        * Report the data type of the instance.
        *
        * @return   A {@link LibraryManager} constant representing the data type.
        */
       public int type()
       {
          return (copyOut || passByPointer) ? LibraryManager.TYPE_POINTER : type;
       }

       /**
        * 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 abstract int size();

       /**
        * 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 abstract long render(long addr);

       /**
        * Copy back (if necessary) data from the native memory and deallocate the memory.
        * <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 abstract void restore(long addr);

       /**
        * Replacement for the default object reading method. The latest
        * state is read from the input source.  The parent's state is
        * read first.
        *
        * @param    in
        *           The input source from which fields will be restored.
        *
        * @throws   IOException
        *           In case of I/O errors.
        * @throws   ClassNotFoundException
        *           If payload can't be instantiated.
        */
       public void readExternal(ObjectInput in)
       throws IOException,
              ClassNotFoundException
       {
          copyIn        = in.readBoolean();
          copyOut       = in.readBoolean();
          passByPointer = in.readBoolean();

          // the memptr is only used on the client side and it is never transferred
          // over the network
       }

       /**
        * Replacement for the default object writing method. The latest
        * state is written to the output destination.  The parent's state is
        * written first.
        *
        * @param    out
        *           The output destination to which fields will be saved.
        *
        * @throws   IOException
        *           In case of I/O errors.
        */
       public void writeExternal(ObjectOutput out)
       throws IOException
       {
          out.writeBoolean(copyIn);
          out.writeBoolean(copyOut);
          out.writeBoolean(passByPointer);

          // the memptr is only used on the client side and it is never transferred
          // over the network
       }
    }