C @(#)filbuf.for	17.1.1.1 (ES0-DMD) 01/25/02 17:15:40
C===========================================================================
C Copyright (C) 1995 European Southern Observatory (ESO)
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 
C the 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
C GNU General Public License for more details.
C
C You should have received a copy of the GNU General Public 
C License along with this program; if not, write to the Free 
C Software Foundation, Inc., 675 Massachusetss Ave, Cambridge, 
C MA 02139, USA.
C
C Corresponding concerning ESO-MIDAS should be addressed as follows:
C	Internet e-mail: midas@eso.org
C	Postal address: European Southern Observatory
C			Data Management Division 
C			Karl-Schwarzschild-Strasse 2
C			D 85748 Garching bei Muenchen 
C			GERMANY
C===========================================================================
C
C+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
C.IDENTIFICATION
C  subroutine FILBUF         version 1.0       880827
C  A. Kruszewski             Warsaw U. Obs.
C.PURPOSE
C  Fill with new data image and mask buffers.
C.INPUT/OUTPUT
C  input arguments:
C  IMF         integer*4           image file logical unit number
C  A           real*4 array        image buffer
C  JAPY        integer*4 array     array with line pointers
C  NX          integer*4           X image dimension
C  IXYU        integer*4 array     limits of accessible area
C  IUSD        integer*4 array     limits of used buffer
C  IBUF        integer*4 array     limits of buffer
C  output arguments:
C  JAPY        integer*4 array     array with line pointers
C  IBUF        integer*4 array     limits of buffer
C-----------------------------------------------------------------------
C
C
      SUBROUTINE FILBUF(IMF, A, JAPY, NX, IXYU, IUSD, IBUF)
C
      IMPLICIT  NONE
      INTEGER   IMF
      REAL      A(1)
      INTEGER   JAPY(1) 
      INTEGER   NX
      INTEGER   IXYU(4)
      INTEGER   IUSD(4)
      INTEGER   IBUF(4)
      INTEGER   JOFF , JSWE
C
      INTEGER   L , LBUF
      INTEGER   NLPB , NPPL , NPIB
C
C ******      Calculate number of pixels per line NPPL,
C ******      number of lines per buffer NLPB
C ******      and number of pixels in buffer NPIB.
C
c      IBS = IBUF(1)
c      JBS = IBUF(2)
c      IBE = IBUF(3)
c      JBE = IBUF(4)
c      NPPL = IXYU(3) - IXYU(1) + 1
      NPPL = IBUF(3) - IBUF(1) + 1
c      NLPB = MIN ( NYBUF , NIBUF/NPPL )
      NLPB = IBUF(4) - IBUF(2) + 1
      NPIB = NPPL * NLPB
c      IF ( NLPB .LE. IUSD(4)-IUSD(2) ) THEN
c            NSIZ = INT( SQRT( FLOAT( NPIB ) ) )
c            NSIZ = MIN( NYBUF , NSIZ )
c            NSIZ = MAX( IUSD(4)-IUSD(2)+1 , NSIZ )
c            ITMP = IUSD(2) - ( NSIZ - IUSD(4)+IUSD(2)-1 ) / 2
c            IBUF(2) = MIN( IUSD(2) , ITMP )
c            IBUF(2) = MAX( IBUF(2) , IXYU(2) )
c            IBUF(4) = MAX( IUSD(4) , IBUF(2) + NSIZ - 1 )
c            IBUF(4) = MIN( IBUF(4) , IXYU(4) )
c            NLPB = IBUF(4) - IBUF(2) + 1
c            IF ( NYBUF .LT. NLPB ) PAUSE 'NYBUF too small'
c            NPPL = NIBUF / NLPB
c            IMEAN = ( IUSD(1) + IUSD(3) ) / 2
c            IBUF(1) = IMEAN - NPPL / 2
c            IBUF(1) = MIN( IBUF(1) , IUSD(1) )
c            IBUF(1) = MAX( IXYU(1) , IBUF(1) )
c            IBUF(3) = IBUF(1) + NPPL - 1
c            IBUF(3) = MAX( IBUF(3) , IUSD(3) )
c            IBUF(3) = MIN( IXYU(3) , IBUF(3) )
c            IF ( NPPL .LE. IBUF(3)-IBUF(1) ) THEN
c                  PAUSE 'too small image buffer'
c            ELSE
c                  NPPL = IBUF(3) - IBUF(1) + 1
c            ENDIF
c            NPIB = NPPL * NLPB
c      ELSE
c            IBUF(1) = IXYU(1)
c            IBUF(2) = IUSD(2)
c            IBUF(3) = IXYU(3)
c            IBUF(4) = MIN( IXYU(4) , IBUF(2)+NLPB-1 )
c      ENDIF
c      IOFF = IBUF(1) - 1
C
C ******      Calculate limiting lines to be read JSWS and JSWE,
C ******      offset to pointers JOFF,
C ******      and number of newly read buffer lines LBUF.
C
c      IF ( IBUF(1) .EQ. IBS .AND. IBUF(3) .EQ. IBE .AND.
c     &                  IBUF(2) .LE. JBE .AND. IBUF(2) .GE. JBS ) THEN
c            JSWS = MAX( JBE+1 , IBUF(2) )
c      ELSE
c            JSWS = IBUF(2)
c      ENDIF
      JSWE = IBUF(4)
      JOFF = IBUF(2) - 1
      LBUF = JSWE - JOFF
C
C ******      Update pointers to buffer lines.
C
      DO 10 L = 1 , LBUF
          JAPY(L) = MOD( (L+JOFF-1)*NPPL , NPIB ) - IBUF(1) + 1
   10      CONTINUE
C
C ******      Read new lines.
C
c      DO 20 J = JSWS , JSWE
c            CALL RDILIN ( IMF , 1 , A(JAPY(J-JOFF)+IOFF+1) , NX ,
c     &                                    J , IOFF , NPPL )
c  20      CONTINUE
C
C ******      Read mask lines.
C
c      DO 30 J = JSWS , JSWE
c            CALL RDMLIN ( MSF , 1 , MA(JAPY(J-JOFF)+IOFF+1) ,
c     &                               NX , J , IOFF , NPPL )
c  30      CONTINUE
C
C ******      Update limits of buffered lines.
C
c      IBUF(2) = JOFF + 1
c      IBUF(4) = JSWE
c 1000   CONTINUE
C
      RETURN
C
      END