C ++********************************************************************
C                                                                      *
C                                                                      *
C                                                                      *
C **********************************************************************
C=* FROM: SPIDER - MODULAR IMAGE PROCESSING SYSTEM.   AUTHOR: J.FRANK  *
C=* Copyright (C) 1985-2005  Health Research Inc.                      *
C=*                                                                    *
C=* HEALTH RESEARCH INCORPORATED (HRI),                                *   
C=* ONE UNIVERSITY PLACE, RENSSELAER, NY 12144-3455.                   *
C=*                                                                    *
C=* Email:  spider@wadsworth.org                                       *
C=*                                                                    *
C=* This program is free software; you can redistribute it and/or      *
C=* modify it under the terms of the GNU General Public License as     *
C=* published by the Free Software Foundation; either version 2 of the *
C=* License, or (at your option) any later version.                    *
C=*                                                                    *
C=* This program is distributed in the hope that it will be useful,    *
C=* but WITHOUT ANY WARRANTY; without even the implied warranty of     *
C=* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU  *
C=* General Public License for more details.                           *
C=*                                                                    *
C=* You should have received a copy of the GNU General Public License  *
C=* along with this program; if not, write to the                      *
C=* Free Software Foundation, Inc.,                                    *
C=* 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.      *
C=*                                                                    *
C **********************************************************************
C                                                                      *
C       THIS SUBROUTINE WILL SHIFT A TWO-DIMENSIONAL ARRAY OR PICTURE
C       STORED ON LUN1 CIRCULARLY BY NSAMS,NROWS;  OUTPUT TO BE FOUND 
C       ON LUN2.
C
C       CALL SHIFT2(LUN1,LUN2,BUF,NSAM,NROW,NSAMS,NROWS)
C         LUN1           LOGICAL UNIT NUMBER OF INPUT IMAGE
C         LUN2           LOGICAL UNIT NUMBER OF OUTPUT IMAGE
C         BUF            REAL BUFFER OF SIZE NSAM
C         NSAM,NROW      DIMENSIONS OF IMAGE
C         NSAMS,NROWS    NUMBER OF SAMPLES AND ROWS TO BE SHIFTED
C
C--*******************************************************************

      SUBROUTINE SHIFT2(LUN1,LUN2,NSAM,NROW,NSAMS,NROWS)

      COMMON BUF(1)

      NS = MOD(NSAMS,NSAM)
      NR = MOD(NROWS,NROW)
      IF(NR.LT.0) NR = NR+NROW
	if(ns.ne.0)  goto  300
      DO  I = 1,NROW
      CALL REDLIN(LUN1,BUF,NSAM,I)
      I1 = I+NR
      IF(I1.GT.NROW) I1=I1-NROW
      CALL WRTLIN(LUN2,BUF,NSAM,I1)
      ENDDO
      RETURN
300   DO  I = 1,NROW
      CALL REDLIN(LUN1,BUF,NSAM,I)
      CALL SHIFT1(BUF,buf(1+nsam),NSAM,NSAMS)
      I1 = I+NR
      IF(I1.GT.NROW) I1=I1-NROW
      CALL WRTLIN(LUN2,BUF(1+nsam),NSAM,I1)
      ENDDO
      END