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FPL — Fortran Processing Library

FPL is a Fortran 90 library designed to facilitate the reading, writing, and processing of data in NetCDF format using dynamic data structures and OpenMP for parallel processing.

Developed at the Federal University of Viçosa (UFV), Brazil — Research Group on Atmosphere-Biosphere Interaction — by Fernando Martins Pimenta.

Features​

  • NetCDF I/O — Read and write 2D, 3D, and 4D grids with support for byte, short, int, float, and double data types
  • Grid generation — Create regular grids from bounding box and resolution parameters
  • Fill value masking — Apply spatial masks using _FillValue with OpenMP parallelization
  • Zonal statistics — Per-zone aggregates (count, mean, min, max, sum, variance) from a data grid grouped by a 2D zone/classification grid, with OpenMP parallelization
  • Cache-optimized — Column-major loop ordering for optimal Fortran memory access patterns
  • Robust error handling — Allocation checks with stat=, explicit intent declarations, pure Fortran diagnostics
  • Shared library — Compiles as libFPL.so for easy linking

Architecture​

The main module src/FPL.f90 aggregates all components via CPP #include directives and compiles as a shared library:

module FPL
  use omp_lib
  use netcdf
  use iso_c_binding
  implicit none
#include "FPL_constants.f90"
#include "FPL_datatypes.f90"
#include "FPL_interfaces.f90"

  contains
#include "FPL_checkerror.f90"
#include "FPL_datetime.f90"
#include "FPL_griddims.f90"
#include "FPL_readgrid.f90"
#include "FPL_writegrid.f90"
#include "FPL_setfillvalue.f90"
#include "FPL_gengrid.f90"
#include "FPL_dealloc.f90"
#include "FPL_fileutils.f90"
#include "FPL_misc.f90"
#include "FPL_sort.f90"
#include "FPL_zonalstats.f90"
end module FPL

The compiler flag -cpp tells gfortran to expand the preprocessor macros at compile time.

Source Modules​

FileLinesDescription
FPL_setfillvalue.f904,033Fill value masking with OpenMP parallel do
FPL_zonalstats.f904,033Zonal statistics with OpenMP parallelization
FPL_writegrid.f901,133Write grids to NetCDF-4 (HDF5 format)
FPL_interfaces.f901,557Generic interfaces (static polymorphism)
FPL_datatypes.f901,133100 derived type definitions via CPP templates
FPL_readgrid.f90833Read variables and coordinates from NetCDF
FPL_gengrid.f90833Generate regular grids from bounding box
FPL_griddims.f90633Read NetCDF dimensions (lon, lat, time, level)
FPL_dealloc.f90633Memory deallocation with stat= checks
FPL_checkerror.f90205Error handling with colored output (pure Fortran)
FPL_fileutils.f90111File utilities: file_exists, countkeys, readheader
FPL_datetime.f9077System date/time (fdate_time, exec_time)
FPL_sort.f9057Bubble sort for dimension ID ordering
FPL_constants.f9049Physical constants and type aliases via iso_c_binding
FPL_misc.f9039Library version
templates/*.inc1,08424 CPP template files (8 modules × 3 dimensions)
generate_cpp.py271Python generator for .f90 instantiation files

Architecture Diagrams​

System Context (C1)​

High-level view of FPL and its external dependencies.

C1 — System Context

Containers (C2)​

Main artifacts that compose the FPL build system.

C2 — Containers

Components (C3)​

Internal modules of the FPL library and their relationships.

C3 — Components

Code Generation​

FPL uses the C preprocessor (CPP) to handle the combinatorial explosion of subroutines for each type/dimension combination. The system has two layers:

  1. Template files (src/templates/*.inc) — Fortran source with CPP macro placeholders (FPL_TYPE, FPL_SUBR, etc.), maintained manually
  2. Generator script (src/generate_cpp.py) — Python script that produces .f90 files with #define/#include/#undef blocks for every type combination

The compiler flag -cpp tells gfortran to expand the macros at compile time. To regenerate:

python3 src/generate_cpp.py
make clean && make

See the Contributing guide for details on adding new templates.

License​

FPL is free software licensed under the GNU General Public License v3.0.

Citing FPL​

PIMENTA, F. M. FPL - Fortran Processing Library (Version 1.0) [Software]. (2016). Viçosa, Minas Gerais - Brazil. http://www.biosfera.dea.ufv.br.

Support​

Atmosphere-Biosphere Research Group