C $Header: /home/ubuntu/mnt/e9_copy/MITgcm/eesupp/inc/CPP_EEOPTIONS.h,v 1.15 2000/11/13 16:20:30 heimbach Exp $
C
C     /==========================================================\
C     | CPP_EEOPTIONS.h                                          |
C     |==========================================================|
C     | C preprocessor "execution environment" supporting        |
C     | flags. Use this file to set flags controlling the        |
C     | execution environment in which a model runs - as opposed |
C     | to the dynamical problem the model solves.               |
C     | Note: Many options are implemented with both compile time|
C     |       and run-time switches. This allows options to be   |
C     |       removed altogether, made optional at run-time or   |
C     |       to be permanently enabled. This convention helps   |
C     |       with the data-dependence analysis performed by the |
C     |       adjoint model compiler. This data dependency       |
C     |       analysis can be upset by runtime switches that it  |
C     |       is unable to recoginise as being fixed for the     |
C     |       duration of an integration.                        |
C     |       A reasonable way to use these flags is to          |
C     |       set all options as selectable at runtime but then  |
C     |       once an experimental configuration has been        |
C     |       identified, rebuild the code with the appropriate  |
C     |       options set at compile time.                       |
C     \==========================================================/

#ifndef _CPP_EEOPTIONS_H_
#define _CPP_EEOPTIONS_H_

C     In general the following convention applies:
C     ALLOW  - indicates an feature will be included but it may
C     CAN      have a run-time flag to allow it to be switched
C              on and off.
C              If ALLOW or CAN directives are "undef'd" this generally
C              means that the feature will not be available i.e. it
C              will not be included in the compiled code and so no
C              run-time option to use the feature will be available.
C
C     ALWAYS - indicates the choice will be fixed at compile time
C              so no run-time option will be present

C     Flag used to indicate whether Fortran formatted write
C     and read are threadsafe. On SGI the routines can be thread
C     safe, on Sun it is not possible - if you are unsure then
C     undef this option.
#undef  FMTFTN_IO_THREADSAFE

C--   Control MPI based parallel processing
#undef  ALLOW_USE_MPI
#undef  ALWAYS_USE_MPI
 
C--   Control use of communication that might overlap computation.
C     Under MPI selects/deselects "non-blocking" sends and receives.
#define ALLOW_ASYNC_COMMUNICATION
#undef  ALLOW_ASYNC_COMMUNICATION
#undef  ALWAYS_USE_ASYNC_COMMUNICATION
C--   Control use of communication that is atomic to computation.
C     Under MPI selects/deselects "blocking" sends and receives.
#define ALLOW_SYNC_COMMUNICATION
#undef  ALWAYS_USE_SYNC_COMMUNICATION

C--   Control use of JAM routines for Artic network
C     These invoke optimized versions of "exchange" and "sum" that
C     utilize the programmable aspect of Artic cards.
#undef  LETS_MAKE_JAM
#undef  JAM_WITH_TWO_PROCS_PER_NODE

C--   Control storage of floating point operands
C     On many systems it improves performance only to use
C     8-byte precision for time stepped variables.
C     Constant in time terms ( geometric factors etc.. )
C     can use 4-byte precision, reducing memory utilisation and
C     boosting performance because of a smaller working
C     set size. However, on vector CRAY systems this degrades
C     performance.
#define REAL4_IS_SLOW
 
C--   Control use of "double" precision constants.
C     Use D0 where it means REAL*8 but not where it means REAL*16
#define D0 d0

C--   Control XY periodicity in processor to grid mappings
C     Note: Model code does not need to know whether a domain is 
C           periodic because it has overlap regions for every box.
C           Model assume that these values have been
C           filled in some way.
#undef  ALWAYS_PREVENT_X_PERIODICITY
#undef  ALWAYS_PREVENT_Y_PERIODICITY
#define CAN_PREVENT_X_PERIODICITY
#define CAN_PREVENT_Y_PERIODICITY

#endif /* _CPP_EEOPTIONS_H_ */

#include "CPP_EEMACROS.h"