libbox-dev 2.5-5 / usr / include / BoxLib / FabConv.H

/*
** (c) 1996-2000 The Regents of the University of California (through
** E.O. Lawrence Berkeley National Laboratory), subject to approval by
** the U.S. Department of Energy.  Your use of this software is under
** license -- the license agreement is attached and included in the
** directory as license.txt or you may contact Berkeley Lab's Technology
** Transfer Department at TTD@lbl.gov.  NOTICE OF U.S. GOVERNMENT RIGHTS.
** The Software was developed under funding from the U.S. Government
** which consequently retains certain rights as follows: the
** U.S. Government has been granted for itself and others acting on its
** behalf a paid-up, nonexclusive, irrevocable, worldwide license in the
** Software to reproduce, prepare derivative works, and perform publicly
** and display publicly.  Beginning five (5) years after the date
** permission to assert copyright is obtained from the U.S. Department of
** Energy, and subject to any subsequent five (5) year renewals, the
** U.S. Government is granted for itself and others acting on its behalf
** a paid-up, nonexclusive, irrevocable, worldwide license in the
** Software to reproduce, prepare derivative works, distribute copies to
** the public, perform publicly and display publicly, and to permit
** others to do so.
*/

#ifndef BL_FABCONV_H
#define BL_FABCONV_H
//
// $Id: FabConv.H,v 1.13 2001/07/26 20:08:45 lijewski Exp $
//
#include <iosfwd>

#include <Array.H>
#include <BLassert.H>
#include <REAL.H>

//
//@Man:
//@Memo: A Descriptor of the Long Integer type
/*@Doc:

  This class is meant to hold all information needed to completely
  describe the "long" type on a machine.  To describe a "long" both
  the number of bytes in the long and their ordering, relative to canonical
  ordering 1 .. sizeof(long), needs to be specified.

  This allows us to write out "long"s in the native format on a machine,
  and then by also saving the IntDescriptor, we can read them back in on
  another machine and have enough information to construct the exact same
  "long" values.
*/

class IntDescriptor
{

public:
    /*@ManDoc: An enumeration describing the two ordering of a "long"
               that we currently support: NormalOrder and ReverseOrder.
               Other ordering may be added as BoxLib is ported to run on
               machines with non-standard "long" orderings.
    */
    enum Ordering { NormalOrder = 1, ReverseOrder = 2 };

    /*@ManDoc: The default constructor.  Does not build a proper IntDescriptor.
               This should only be used when you need to build a generic
               IntDescriptor in order to be able to read in a specific
               one from an istream.
    */
    IntDescriptor ();
    //
    //@ManDoc: Construct a specific IntDescriptor.
    //
    IntDescriptor (long     nb,
                   Ordering ordering = NormalOrder);
    //
    //@ManDoc: Returns the ordering of the "long".
    //
    Ordering order () const;
    //
    //@ManDoc: Returns the number of bytes in a "long".
    //
    int numBytes () const;
    //
    //@ManDoc: The equality operator.
    //
    bool operator== (const IntDescriptor& id) const;
    //
    //@ManDoc: The inequality operator.
    //
    bool operator!= (const IntDescriptor& id) const;

protected:
    long     numbytes;
    Ordering ord;
};

//
//@ManDoc: Write out an IntDescriptor to an ostream in ASCII.
//
std::ostream& operator<< (std::ostream& os, const IntDescriptor& id);
//
//@ManDoc: Read in an IntDescriptor from an istream.
//
std::istream& operator>> (std::istream& is, IntDescriptor& id);

//
//@Man:
//@Memo: A Descriptor of the Real Type
/*@Doc:

  This class is meant to hold all information needed to completely
  describe the "Real" floating-point type on a machine.  By "Real" here we
  mean either the "float" or "double" type that this version of BoxLib
  was built with, which corresponds to whether BL\_USE\_FLOAT or
  BL\_USE\_DOUBLE was used to build the version of the library.
  
  To describe a "Real" type two arrays are needed: one detailing the ordering
  of the bytes in the Real, relative to the canonical ordering
  1 .. sizeof(Real) and the other detailing the format of the floating-point
  number.

  The array detailing the format of a floating-point number is an eight-element
  array of longs containing the following information:

          format[0] = number of bits per number
          format[1] = number of bits in exponent
          format[2] = number of bits in mantissa
          format[3] = start bit of sign
          format[4] = start bit of exponent
          format[5] = start bit of mantissa
          format[6] = high order mantissa bit (CRAY needs this)
          format[7] = bias of exponent

  This allows us to write out "Real"s in the native format on a machine,
  and then by also saving the IntDescriptor, we can read them back in on
  another machine and have enough information to construct the exact same
  "Real" values, provided the Reals have the same size on the two machines.
*/

class RealDescriptor
{
public:
    /*@ManDoc: The default constructor.  Does not build a proper
               RealDescriptor. This should only be used when you need to
               build a generic RealDescriptor in order to be able to read
               in a specific one from an istream.
    */
    RealDescriptor ();

    /*@ManDoc: Construct a specific RealDescriptor, passing in the format
               of the Real, the order of the Real, and the length of the
               array detailing the ordering.
    */
    RealDescriptor (const long* format,
                    const int*  order,
                    int         order_length);
    //
    //@ManDoc: The copy constructor.
    //
    RealDescriptor (const RealDescriptor& rhs);
    //
    //@ManDoc: The assignment operator.
    //
    RealDescriptor& operator= (const RealDescriptor& rhs);
    //
    //@ManDoc: Destructor is virtual incase a derived class has a non-trivial
    //         destructor.
    virtual ~RealDescriptor ();
    //
    //@ManDoc: Returns the format array as a `const long*'
    //
    const long* format () const;
    //
    //@ManDoc: Returns const Array<long> reference to the format array.
    //
    const Array<long>& formatarray () const;
    //
    //@ManDoc: Returns the order array as a `const int*'
    //
    const int* order () const;
    //
    //@ManDoc: Returns const Array<int> reference to the order array.
    //
    const Array<int>& orderarray () const;
    //
    //@ManDoc: Returns the number of bytes in the Real.
    //
    int numBytes () const;
    //
    //@ManDoc: The equality operator.
    //
    bool operator== (const RealDescriptor& rd) const;
    //
    //@ManDoc: The inequality operator.
    //
    bool operator != (const RealDescriptor& rd) const;

    //
    //@ManDoc: Set to always fix denormals when converting to native format.
    //
    static void SetFixDenormals();

    /*@ManDoc: Returns a copy of this RealDescriptor on the heap.
               The user is responsible for deletion.
    */
    virtual RealDescriptor* clone () const;

    /*@ManDoc: Returns a RealDescriptor on the heap detailing requested
               floating-point type.  Here format, precision, and ordering
               correspond to the enumerations in FABio.  This is here to
               support reading "old" FABs.  Do NOT use it in new code.
    */
    static RealDescriptor* newRealDescriptor (int         format,
                                              int         precision,
                                              const char* systype,
                                              int         ordering);

    /*@ManDoc: Convert nitems in RealDescriptor format to native Real format.
               The out array is assumed to be large enough to hold the
               resulting output.
    */
    static void convertToNativeFormat (Real*                 out,
                                       long                  nitems,
                                       void*                 in,
                                       const RealDescriptor& id);

    /*@ManDoc: Read nitems from istream in ReadDescriptor format and
               convert them to the native Real format.  The out array is
               assumed to be large enough to hold the resulting output.
    */
    static void convertToNativeFormat (Real*                 out,
                                       long                  nitems,
                                       std::istream&         is,
                                       const RealDescriptor& id);

    /*@ManDoc: Convert nitems Reals in native format to RealDescriptor format
               and write them to the ostream.
    */
    static void convertFromNativeFormat (std::ostream&         os,
                                         long                  nitems,
                                         const Real*           in,
                                         const RealDescriptor& od);

    /*@ManDoc: Convert nitems Reals in native format to RealDescriptor format.
               The out array is assumed to be large enough to hold the
               resulting output.
    */
    static void convertFromNativeFormat (void*                 out,
                                         long                  nitems,
                                         Real*                 in,
                                         const RealDescriptor& od);
protected:
    Array<long> fr;
    Array<int>  ord;
    static bool bAlwaysFixDenormals;
};

//
//@ManDoc: Write out an RealDescriptor to an ostream in ASCII.
//
std::ostream& operator<< (std::ostream& os, const RealDescriptor& id);
//
//@ManDoc: Read in a RealDescriptor from an istream.
//
std::istream& operator>> (std::istream& is, RealDescriptor& id);

#endif /*BL_FABCONV_H*/