C++*********************************************************************
C
C $$ SHFI_2.FOR
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
C IMAGE_PROCESSING_ROUTINE
C
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C--*********************************************************************
C
C $$ SHFI_2.FOR

        SUBROUTINE  SHFI_2(X,OUT,NSAM,NROW,ISHX,ISHY)
        DIMENSION  X(NSAM,NROW),OUT(NSAM,NROW)
        INTEGER  RN2,SN2,RW2,RS2,XI,YI,SHX,SHY,YOLD,XOLD

        SHX=MOD(ISHX,NSAM)
        SHY=MOD(ISHY,NROW)
        ICENT=NROW/2+1
        KCENT=NSAM/2+1
        RN2=-NROW/2
        SN2=-NSAM/2
        RW2=-RN2
        RS2=-SN2

        IF(MOD(NSAM,2).EQ.0)  RW2=RW2-1
        IF(MOD(NROW,2).EQ.0)  RS2=RS2-1
c$omp parallel do private(i,k,yi,yold,xi,xold)
        DO    I=1,NROW
           YI=I-ICENT-SHY
           IF(YI.LT.RN2)  YI=MIN0(RW2+YI-RN2+1,RW2)
           IF(YI.GT.RW2)  YI=MAX0(RN2+YI-RW2-1,RN2)
           YOLD=YI+ICENT

           DO    K=1,NSAM
              XI=K-KCENT-SHX
              IF(XI.LT.SN2)  XI=MIN0(RS2+XI-SN2+1,RS2)
              IF(XI.GT.RS2)  XI=MAX0(SN2+XI-RS2-1,SN2)
              XOLD=XI+KCENT
              OUT(K,I)=X(XOLD, YOLD)
           ENDDO
        ENDDO
        END