LMDZ Coding conventions and guidelines

Coding rules related to GPU porting with GPU-Morphosis are available on this webpage.

Generalities

• IMPLICT NONE
• For declarations of input/inout/output variables, systematically specify INTENT(IN), INTENT(INOUT), or INTENT(OUT)

Mor generally, all the variables in a routine must be 'properly' declared with TYPE, DIMENSION and INTENT for arguments to the routine

• It is HIGHLY RECOMMENDED to comment every input/output/inout variable with a short definition and the units.
• Be generous and rigorous when commenting routines (of course)
• Fortran keywords in fortran files will be in UPPER case
• Indent your routine. We recommend using the script format_code.sh (based on fprettify) in LMDZ/tools for this purpose.
• In the physics module, all SAVE variables should be declared as THREADPRIVATE (this includes all variables that are initialized in their declaration)

1   LOGICAL, SAVE :: first = .TRUE.
2   !$OMP THREADPRIVATE(first)

• Variables and functions included through modules should be explicitly defined through the USE ..., ONLY statement:

1 USE ioipsl_getin_p_mod, ONLY : getin_p

Naming of modules

Module names should have a lmdz_ prefix. For example, the file lmdz_wave.F90 would be a module containing one or more subroutines:

 1   MODULE lmdz_wave
 2   IMPLICIT NONE
 3 
 4   CONTAINS
 5 
 6   SUBROUTINE wave_init (...)
 7   ...
 8   END SUBROUTINE wave_init
 9 
10   SUBROUTINE wave_calc (...)
11   ...
12   END SUBROUTINE wave_calc
13 
14   END MODULE lmdz_wave

Beware: the renaming of already existing parametrization modules (to the lmdz_ format) should only occur once they have been re-written to adhere to the coding conventions for parametrizations (see below) as we use it as a marker that the recoding work on that particular parametrization has been done.

Coding conventions for parametrizations

Following different discussions among LMDZ developpers (summarized in one of our weekly meetings here), the following coding rules apply to the development of LMDZ parametrizations:

• constants and variables that need to be initialized for all routines of a given "group" of parametrizations groupparam should be declared and initialized in a specific initialisation module called lmdz_groupparam_ini

1 MODULE lmdz_groupparam_ini
2 REAL, SAVE :: cst1
3 !$OMPTREADPRIVATE cst1
4 ...
5 END MODULE lmdz_groupparam_ini

• the routines associated to a parametrization can either be gathered in a unique module or each have their own module. The name of the module will reflect the group of parametrizations the routine belongs to.
• Furthermore, to make parameterizations as independent as possible, each parameterization should use only one module, which corresponds to the "ini" of its group.

1 MODULE lmdz_groupparam1_subroutine1
2 CONTAINS
3 SUBROUTINE param1_subroutine1
4 USE lmdz_groupparam1_ini, ONLY : cst1
5 ...
6 END SUBROUTINE param1_subroutine1
7 END MODULE lmdz_groupparam1_subroutine1

• the first arguments of parametrization routines should be the dimensions of the domain (e.g. klon, klev)

 1 MODULE lmdz_param1_subroutine1
 2 CONTAINS
 3 SUBROUTINE param1_subroutine1(klon, klev, ..., dtdwn, dqdwn, ..., dth, ...)
 4 ! Input arguments to routine
 5 INTEGER, INTENT(IN) :: klon,klev
 6 REAL, DIMENSION (klon, klev),     INTENT(IN)          :: dtdwn, dqdwn
 7 ...
 8 ! Output arguments
 9 REAL, DIMENSION (klon, klev),     INTENT(OUT)         :: dth
10 ...
11 ! Local variables
12 REAL, DIMENSION(klon)                                 :: act
13 ...

• all dimensions of tables (e.g. nbsrf) should be passed as arguments to the routine rather than passed through a module

24 janvier 2025 à 17:37 (CET)