blockio.h

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//# blockio.h:
//# Copyright (C) 1993,1994,1995,1996,1999
//# Associated Universities, Inc. Washington DC, USA.
//# 
//# This library is free software; you can redistribute it and/or modify it
//# under the terms of the GNU Library General Public License as published by
//# the Free Software Foundation; either version 2 of the License, or (at your
//# option) any later version.
//# 
//# This library 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 Library General Public
//# License for more details.
//# 
//# You should have received a copy of the GNU Library General Public License
//# along with this library; if not, write to the Free Software Foundation,
//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
//# 
//# Correspondence concerning AIPS++ should be addressed as follows:
//#        Internet email: aips2-request@nrao.edu.
//#        Postal address: AIPS++ Project Office
//#                        National Radio Astronomy Observatory
//#                        520 Edgemont Road
//#                        Charlottesville, VA 22903-2475 USA
//#
//# $Id$
#ifndef FITS_BLOCKIO_H
#define FITS_BLOCKIO_H

//# Include this file first, because it may set LFS variables used by cfitsio.
#include <casacore/casa/aips.h>

//# Make sure that cfitsio does not declare the wcs headers.
extern "C"{
#include <fitsio.h>  //# header file from cfitsio
#include <fitsio2.h> //# using core functions of cfitsio
}

#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>

#include <casacore/fits/FITS/FITSError.h>

namespace casacore { //# NAMESPACE CASACORE - BEGIN

//----------------------------------------------------------------------------
//<category lib=aips module=FITS sect="Blocked I/O">   
//<summary> fixed-length blocked sequentual I/O base class </summary> 
//<synopsis>
// BlockIO is a low level base class that implements fixed-length 
// blocked sequential I/O. Its derived classes, BlockInput and BlockOutput
// are used by the FitsInput and FitsOutput classes. Users will hardly ever
// need to use this class directly.
//</synopsis>
//<todo>
// <li> ifdef kludges until OS dependent flags are developed
//       for the compilation system.
//</todo>

class BlockIO {
    public:
    // error return code
    enum IOErrs { OK, NOSUCHFILE, NOMEM, OPENERR, CLOSEERR, 
        READERR, WRITEERR };
    int err() const { return (int)m_err_status; }

    //  number of physical blocks read/written
    int blockno() const { return m_block_no; }
    
    // reset the m_iosize data member
    void reset_iosize() { m_iosize = 0; }
    
    // get the total bytes of data in m_buffer
    int iosize() const { return m_iosize; }
    
    // get the current read position within m_buffer
    int current() const { return m_current; }
    
    // get m_buffer
    char* buffer() const { return m_buffer; }

    //  number of logical records read/written
    int recno() const { return m_rec_no; }

    // name of file associated with I/O stream, if applicable
    const char *fname() const { return m_filename; }

    // fits_close_file() does not work for reasons that the file pointer does not have the 
    // knowledge of chdu which were written with write_hdr() not write_***_hdr(). So create
    // our own close_file() method.
        int close_file( fitsfile *fptr, int *status);
    // file descriptor associated with I/O stream, if applicable
    int fdes() const { return m_fd; }
    // get the fitsfile pointer
    fitsfile *getfptr() const { return m_fptr; } 
    void setfptr( fitsfile* ffp );
    protected:
    // Construction can be done either from a filename with open options 
    // or from a file descriptor.
    //
    // The remaining arguments are the the logical record size and number
    // of records that make up a physical record followed by the 
    // output stream that is used to write error messages to.
    //<group>
    BlockIO(const char *, int, int, int = 1, 
        FITSErrorHandler errhandler = FITSError::defaultHandler);
    BlockIO(int,               int, int = 1, 
        FITSErrorHandler errhandler = FITSError::defaultHandler);
    virtual ~BlockIO();
    //</group>

    char *m_filename;            // name of file
    int m_options;              // options on open statement
    const int m_recsize;         // size in bytes of a logical record
    const int m_nrec;            // maximum number of logical records
    const int m_blocksize;    // size in bytes of physical records
   FITSErrorHandler m_errfn; // FITS error handler function
    IOErrs m_err_status;    // error number
    int m_fd;              // file descriptor
    char *m_buffer;     // the actual data buffer itself
    int m_block_no;     // number of physical blocks read/written
    int m_rec_no;          // number of logical records read/written
    int m_current;      // offset to current logical record
    // size of record in buffer
    int m_iosize;
    // using fitsfile structure from cfitsio of NASA
    fitsfile *m_fptr;       

    // set the error message and error number for later recovery
    void errmsg(IOErrs, const char *);
};

//<summary> fixed-length blocked sequential input base class</summary>
//<prerequisite>
//   <li> BlockIO
//</prerequisite>

class BlockInput : public BlockIO {
    public:
    // Construction can be done either from a filename or from
    // a file descriptor.
    //
    // The remaining arguments are the the logical record size and number
    // of records that make up a physical record followed by the 
    // output stream that is used to write error messages to.
    //<group>
    BlockInput(const char *, int, int = 1, 
           FITSErrorHandler errhandler = FITSError::defaultHandler);
    BlockInput(int,          int, int = 1, 
           FITSErrorHandler errhandler = FITSError::defaultHandler);
    virtual ~BlockInput();
    //</group>

    // read the next logical record or first
    // skip N logical records and then read the next one.
    // (note it is not possible to skip a record without
    // reading a record). 
    //<note role=caution> these functions return a pointer to an
    // internal record. The user must make sure that
    // after destruction of this class no dangling pointers
    // are left.
    //</note>
    //<group>
    virtual char *read();       // read a physical block.  
    virtual char *skip(int);    
    //</group>
};

//<summary> fixed-length blocked sequential output base class</summary>
//<prerequisite>
//   <li> BlockIO
//</prerequisite>             

class BlockOutput : public BlockIO {
    public:
    // Construction can be done either from a filename or from
    // a file descriptor.
    //
    // The remaining arguments are the the logical record size and number
    // of records that make up a physical record followed by the 
    // output stream that is used to write error messages to.
    //<group>
    BlockOutput(const char *, int, int = 1,
            FITSErrorHandler errhandler = FITSError::defaultHandler);
    BlockOutput(int,          int, int = 1,
            FITSErrorHandler errhandler = FITSError::defaultHandler);
    virtual ~BlockOutput();
        void flush_buffer();
    //</group>

    // write the next logical record. The input must point
    // to a logical record
    virtual int write(char *);
};

} //# NAMESPACE CASACORE - END

# endif