//MACRO     Sext.w          DReg,       {optional},     SReg
//--------------------------------------------------------------------------------------------------
//
//  @ CopyRight Roberti & Parau Enterprises, Inc.  2021-2023
//
//  This work is licensed under the Creative Commons Attribution-NoDerivatives 4.0 International License.
//  To view a copy of this license, visit http://creativecommons.org/licenses/by-nd/4.0/
//   or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.
//
//--------------------------------------------------------------------------------------------------
//
    if (SReg != null)
\#Label		ADDIW		#DReg, 0[#SReg]						// Extend word sign to double word
    else
\#Label		ADDIW		#DReg, 0							// Extend word sign to double word