fms.F90

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!***********************************************************************
!*                   GNU Lesser General Public License
!*
!* This file is part of the GFDL Flexible Modeling System (FMS).
!*
!* FMS is free software: you can redistribute it and/or modify it under
!* the terms of the GNU Lesser General Public License as published by
!* the Free Software Foundation, either version 3 of the License, or (at
!* your option) any later version.
!*
!* FMS 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 General Public License
!* for more details.
!*
!* You should have received a copy of the GNU Lesser General Public
!* License along with FMS.  If not, see <http://www.gnu.org/licenses/>.
!***********************************************************************

module fms_mod

! <CONTACT EMAIL="Bruce.Wyman@noaa.gov">
!   Bruce Wyman
! </CONTACT>

! <HISTORY SRC="http://www.gfdl.noaa.gov/fms-cgi-bin/cvsweb.cgi/FMS/"/>

! <OVERVIEW>
!   The fms module provides routines that are commonly used
!   by most FMS modules.
! </OVERVIEW>

! <DESCRIPTION>
!   Here is a summary of the functions performed by routines
!     in the fms module.
!
!   1. Output module version numbers to a common (<TT>log</TT>) file
!     using a common format.<BR/>
!   2. Open specific types of files common to many FMS modules.
!     These include namelist files, restart files, and 32-bit IEEE
!     data files. There also is a matching interface to close the files.
!     If other file types are needed the <TT>mpp_open</TT> and <TT>mpp_close</TT>
!     interfaces in module <LINK SRC="http://www.gfdl.noaa.gov/fms-cgi-bin/cvsweb.cgi/FMS/shared/mpp/mpp_io.html">mpp_io</LINK> must be used.<BR/>
!    3. Read and write distributed data to simple native unformatted files.
!     This type of file (called a restart file) is used to checkpoint
!     model integrations for a subsequent restart of the run.<BR/>
!    4. For convenience there are several routines published from
!     the <LINK SRC="http://www.gfdl.noaa.gov/fms-cgi-bin/cvsweb.cgi/FMS/shared/mpp/mpp.html">mpp</LINK> module. These are routines for getting processor
!     numbers, commonly used I/O unit numbers, error handling, and timing sections of code.
! </DESCRIPTION>

!-----------------------------------------------------------------------
!
!         A collection of commonly used routines.
!
!  The routines are primarily I/O related, however, there also
!  exists several simple miscellaneous utility routines.
!
!-----------------------------------------------------------------------
!
!  file_exist         Checks the existence of the given file name.
!
!  check_nml_error    Checks the iostat argument that is returned after
!                     reading a namelist and determines if the error
!                     code is valid.
!
!  write_version_number  Prints to the log file (or a specified unit)
!                        the (cvs) version id string and (cvs) tag name.
!
!  error_mesg          Print notes, warnings and error messages, 
!                      terminates program for error messages.
!                      (use error levels NOTE,WARNING,FATAL)
!
!  open_namelist_file  Opens namelist file for reading only.
!
!  open_restart_file   Opens a file that will be used for reading or writing
!                      restart files with native unformatted data.
!
!  open_ieee32_file    Opens a file that will be used for reading or writing
!                      unformatted 32-bit ieee data.
!
!  close_file          Closes a file that was opened using 
!                      open_namelist_file, open_restart_file, or
!                      open_ieee32_file.
!
!  set_domain          Call this routine to internally store in fms_mod the
!                      domain2d data type prior to calling the distributed
!                      data I/O routines read_data and write_data.
!
!  read_data           Reads distributed data from a single threaded file.
!
!  write_data          Writes distributed data to a single threaded file.
!
!  fms_init            Initializes the fms module and also the
!                      mpp_io module (which initializes all mpp mods).
!                      Will be called automatically if the user does
!                      not call it.
!
!  fms_end             Calls mpp exit routines.
!
!  lowercase           Convert character strings to all lower case
!
!  uppercase           Convert character strings to all upper case
!
!  monotonic_array     Determines if the real input array has
!                      monotonically increasing or decreasing values.
!
!  string_array_index  Match the input character string to a string
!                      in an array/list of character strings.
!
!-----------------------------------------------------------------------
!---- published routines from mpp_mod ----
!
!   mpp_error, NOTE, WARNING, FATAL
!   mpp_error_state
!   mpp_pe, mpp_npes, mpp_root_pe
!   stdin, stdout, stderr, stdlog
!   mpp_chksum
!
!   mpp_clock_id, mpp_clock_begin , mpp_clock_end
!   MPP_CLOCK_SYNC, MPP_CLOCK_DETAILED
!   CLOCK_COMPONENT, CLOCK_SUBCOMPONENT, CLOCK_MODULE_DRIVER, 
!   CLOCK_MODULE, CLOCK_ROUTINE, CLOCK_LOOP, CLOCK_INFRA
!
!-----------------------------------------------------------------------

use          mpp_mod, only:  mpp_error, note, warning, fatal,    &
                             mpp_set_warn_level,                 &
                             mpp_transmit, all_pes,              &
                             mpp_pe, mpp_npes, mpp_root_pe,      &
                             mpp_sync, mpp_chksum,               &
                             mpp_clock_begin, mpp_clock_end,     &
                             mpp_clock_id, mpp_init, mpp_exit,   &
                             mpp_clock_sync, mpp_clock_detailed, &
                             clock_component, clock_subcomponent,&
                             clock_module_driver, clock_module,  &
                             clock_routine, clock_loop,          &
                             clock_infra, mpp_clock_set_grain,   &
                             mpp_set_stack_size,                 &
                             stdin, stdout, stderr, stdlog,      &
                             mpp_error_state, lowercase,         &
                             uppercase, mpp_broadcast, input_nml_file

use  mpp_domains_mod, only:  domain2d, mpp_define_domains, &
                             mpp_update_domains, global_data_domain, &
                             mpp_domains_init, mpp_domains_exit,     &
                             mpp_global_field, mpp_domains_set_stack_size,  &
                             mpp_get_compute_domain, mpp_get_global_domain, &
                             mpp_get_data_domain

use       mpp_io_mod, only:  mpp_io_init, mpp_open, mpp_close,         &
                       mpp_ascii, mpp_native, mpp_ieee32, mpp_netcdf,  &
                       mpp_rdonly, mpp_wronly, mpp_append, mpp_overwr, &
                       mpp_sequential, mpp_direct,                     &
                       mpp_single, mpp_multi, mpp_delete, mpp_io_exit, &
                       fieldtype, mpp_get_atts, mpp_get_info, mpp_get_fields, &
                       do_cf_compliance

use fms_io_mod, only : fms_io_init, fms_io_exit, field_size, &
                       read_data, write_data, read_compressed, read_distributed, &
                       open_namelist_file, open_restart_file, open_ieee32_file, close_file, &
                       set_domain, get_domain_decomp, nullify_domain, &
                       open_file, open_direct_file, string, get_mosaic_tile_grid, &
                       get_mosaic_tile_file, get_global_att_value, file_exist, field_exist, &
                       write_version_number

use memutils_mod, only: print_memuse_stats, memutils_init
use constants_mod, only: constants_version=>version !pjp: PI not computed


implicit none
private

! routines for initialization and termination of module
public :: fms_init, fms_end

! routines for opening/closing specific types of file
public :: open_namelist_file, open_restart_file, &
          open_ieee32_file, close_file, &
          open_file, open_direct_file

! routines for reading/writing distributed data
public :: set_domain, read_data, write_data, read_compressed, read_distributed
public :: get_domain_decomp, field_size, nullify_domain
public :: get_global_att_value

! routines for get mosaic information
public :: get_mosaic_tile_grid, get_mosaic_tile_file

! miscellaneous i/o routines
public :: file_exist, check_nml_error, field_exist,     &
          error_mesg, fms_error_handler
! i/o routines from fms_io
public :: write_version_number

! miscellaneous utilities (non i/o)
public :: lowercase, uppercase, string,        &
          string_array_index, monotonic_array

! public mpp interfaces
public :: mpp_error, note, warning, fatal, &
          mpp_error_state,                 &
          mpp_pe, mpp_npes, mpp_root_pe,   &
          stdin, stdout, stderr, stdlog,   &
          mpp_chksum
public :: mpp_clock_id, mpp_clock_begin, mpp_clock_end
public :: mpp_clock_sync, mpp_clock_detailed
public :: clock_component, clock_subcomponent, &
          clock_module_driver, clock_module,   &
          clock_routine, clock_loop, clock_infra
! public mpp-io interfaces
public :: do_cf_compliance

!Balaji
!this is published by fms and applied to any initialized clocks
!of course you can go and set the flag to SYNC or DETAILED by hand
integer, public :: clock_flag_default

! Namelist read error values
  TYPE nml_errors_type
     INTEGER :: multiplenmlsinfile
     INTEGER :: badtype1
     INTEGER :: badtype2
     INTEGER :: missingvar
     INTEGER :: notinfile
  END TYPE nml_errors_type
  TYPE(nml_errors_type), SAVE :: nml_errors


!------ namelist interface -------
!------ adjustable severity level for warnings ------

  logical           :: read_all_pe   = .true.
  character(len=16) :: clock_grain = 'NONE', clock_flags='NONE'
  character(len=8)  :: warning_level = 'warning'
  character(len=64) :: iospec_ieee32 = '-N ieee_32'
  integer           :: stack_size = 0
  integer           :: domains_stack_size = 0
  logical, public   :: print_memory_usage = .false.

!------ namelist interface -------

! <NAMELIST NAME="fms_nml">
!   <DATA NAME="clock_grain"  TYPE="character"  DEFAULT="'NONE'">
!     The level of clock granularity used for performance timing sections
!     of code. Possible values in order of increasing detail are:
!     'NONE', 'COMPONENT', 'SUBCOMPONENT', 'MODULE_DRIVER', 'MODULE', 'ROUTINE',
!     'LOOP', and 'INFRA'.  Code sections are defined using routines in MPP 
!     module: mpp_clock_id, mpp_clock_begin, and mpp_clock_end.
!     The fms module makes these routines public.
!     A list of timed code sections will be printed to STDOUT.
!     See the <LINK SRC="http://www.gfdl.noaa.gov/fms-cgi-bin/cvsweb.cgi/FMS/shared/mpp/mpp.html">MPP</LINK>
!     module for more details.
!   </DATA>
!   <DATA NAME="clock_flags"  TYPE="character"  DEFAULT="'NONE'">
!     Possible values are 'NONE', 'SYNC', or 'DETAILED'.
!     SYNC will give accurate information on load balance of the clocked
!     portion of code.
!     DETAILED also turns on detailed message-passing performance diagnosis.
!     Both SYNC and DETAILED will  work correctly on innermost clock nest
!     and distort outer clocks, and possibly the overall code time.
!     See the <LINK SRC="http://www.gfdl.noaa.gov/fms-cgi-bin/cvsweb.cgi/FMS/shared/mpp/mpp.html">MPP</LINK>
!     module for more details.
!   </DATA>
!   <DATA NAME="read_all_pe"  TYPE="logical"  DEFAULT="true">
!     Read global data on all processors extracting local part needed (TRUE) or
!     read global data on PE0 and broadcast to all PEs (FALSE).
!   </DATA>
!   <DATA NAME="warning_level"  TYPE="character"  DEFAULT="'warning'">
!     Sets the termination condition for the WARNING flag to interfaces
!     error_mesg/mpp_error. set warning_level = 'fatal' (program crashes for
!     warning messages) or 'warning' (prints warning message and continues).
!   </DATA>
!   <DATA NAME="iospec_ieee32"  TYPE="character"  DEFAULT="'-N ieee_32'">
!     iospec flag used with the open_ieee32_file interface.
!   </DATA>
!   <DATA NAME="stack_size"  TYPE="integer"  DEFAULT="0">
!     The size in words of the MPP user stack. If stack_size > 0, the following
!     MPP routine is called: call mpp_set_stack_size (stack_size). If stack_size
!     = 0 (default) then the default size set by mpp_mod is used.
!   </DATA>
!   <DATA NAME="domains_stack_size" TYPE="integer"  DEFAULT="0">
!     The size in words of the MPP_DOMAINS user stack. If
!     domains_stack_size > 0, the following MPP_DOMAINS routine is called:
!     call mpp_domains_set_stack_size (domains_stack_size). If
!     domains_stack_size = 0 (default) then the default size set by
!     mpp_domains_mod is used. 
!   </DATA>
!   <DATA NAME="print_memory_usage"  TYPE="logical"  DEFAULT=".FALSE.">
!     If set to .TRUE., memory usage statistics will be printed at various
!     points in the code. It is used to study memory usage, e.g to detect
!     memory leaks.
!   </DATA>
! </NAMELIST>

  namelist /fms_nml/  read_all_pe, clock_grain, clock_flags,    &
                      warning_level, iospec_ieee32, &
                      stack_size, domains_stack_size, &
                      print_memory_usage

!   ---- private data for check_nml_error ----

   integer, private :: num_nml_error_codes, nml_error_codes(20)
   logical, private :: do_nml_error_init = .true.
   private  nml_error_init


!  ---- version number -----

! Include variable "version" to be written to log file.
#include<file_version.h>

  logical :: module_is_initialized = .false.


contains

!#######################################################################

! <SUBROUTINE NAME="fms_init">

!   <OVERVIEW>
!     Initializes the FMS module and also calls the initialization routines for all
!     modules in the MPP package. Will be called automatically if the user does
!     not call it. 
!   </OVERVIEW>
!   <DESCRIPTION>
!      Initialization routine for the fms module. It also calls initialization routines
!      for the mpp, mpp_domains, and mpp_io modules. Although this routine
!      will be called automatically by other fms_mod routines, users should
!      explicitly call fms_init. If this routine is called more than once it will
!      return silently. There are no arguments.
!   </DESCRIPTION>
!   <TEMPLATE>
!     call fms_init ( )
!   </TEMPLATE>


!   <ERROR MSG="invalid entry for namelist variable warning_level" STATUS="FATAL">
!     The namelist variable warning_level must be either 'fatal' or 'warning'
!     (case-insensitive). 
!   </ERROR>
!   <ERROR MSG="invalid entry for namelist variable clock_grain" STATUS="FATAL">
!     The namelist variable clock_grain must be one of the following values:
!     'NONE', 'COMPONENT', 'SUBCOMPONENT', 'MODULE_DRIVER', 'MODULE', 'ROUTINE',
!     'LOOP', or 'INFRA' (case-insensitive). 
!   </ERROR>

! initializes the fms module/package
! also calls mpp initialization routines and reads fms namelist

subroutine fms_init (localcomm )
 integer, intent(in), optional :: localcomm
 integer :: unit, ierr, io

    if (module_is_initialized) return    ! return silently if already called
    module_is_initialized = .true.
!---- initialize mpp routines ----
    if(present(localcomm)) then
       call mpp_init(localcomm=localcomm)
    else
       call mpp_init()
    endif
    call mpp_domains_init
    call fms_io_init

!---- read namelist input ----

    call nml_error_init  ! first initialize namelist iostat error codes

#ifdef INTERNAL_FILE_NML
      read (input_nml_file, fms_nml, iostat=io)
      ierr = check_nml_error(io,'fms_nml')
#else
    if (file_exist('input.nml')) then
       unit = open_namelist_file( )
       ierr=1; do while (ierr /= 0)
          read  (unit, nml=fms_nml, iostat=io, end=10)
          ierr = check_nml_error(io,'fms_nml')  ! also initializes nml error codes
       enddo
 10    call mpp_close (unit)
    endif
#endif

!---- define mpp stack sizes if non-zero -----

    if (        stack_size > 0) call         mpp_set_stack_size (        stack_size)
    if (domains_stack_size > 0) call mpp_domains_set_stack_size (domains_stack_size)

!---- set severity level for warnings ----

    select case( trim(lowercase(warning_level)) )
    case( 'fatal' )  
        call mpp_set_warn_level ( fatal )
    case( 'warning' )
        call mpp_set_warn_level ( warning )
    case default
        call error_mesg ( 'fms_init',  &
             'invalid entry for namelist variable warning_level', fatal )
    end select

!--- set granularity for timing code sections ---

    select case( trim(uppercase(clock_grain)) )
    case( 'NONE' )
        call mpp_clock_set_grain (0)
    case( 'COMPONENT' )
        call mpp_clock_set_grain (clock_component)
    case( 'SUBCOMPONENT' )
        call mpp_clock_set_grain (clock_subcomponent)
    case( 'MODULE_DRIVER' )
        call mpp_clock_set_grain (clock_module_driver)
    case( 'MODULE' )
        call mpp_clock_set_grain (clock_module)
    case( 'ROUTINE' )
        call mpp_clock_set_grain (clock_routine)
    case( 'LOOP' )
        call mpp_clock_set_grain (clock_loop)
    case( 'INFRA' )
        call mpp_clock_set_grain (clock_infra)
    case default
        call error_mesg ( 'fms_init',  &
             'invalid entry for namelist variable clock_grain', fatal )
    end select
!Balaji
    select case( trim(uppercase(clock_flags)) )
    case( 'NONE' )
       clock_flag_default = 0
    case( 'SYNC' )
       clock_flag_default = mpp_clock_sync
    case( 'DETAILED' )
       clock_flag_default = mpp_clock_detailed
    case default
       call error_mesg ( 'fms_init',  &
            'invalid entry for namelist variable clock_flags', fatal )
   end select

!--- write version info and namelist to logfile ---

    call write_version_number("FMS_MOD", version)
    if (mpp_pe() == mpp_root_pe()) then
      unit = stdlog()
      write (unit, nml=fms_nml)
      write (unit,*) 'nml_error_codes=', nml_error_codes(1:num_nml_error_codes)
    endif

    call memutils_init( print_memory_usage )
    call print_memuse_stats('fms_init')

    call write_version_number("CONSTANTS_MOD", constants_version)

end subroutine fms_init
! </SUBROUTINE>

!#######################################################################


! <SUBROUTINE NAME="fms_end">

!   <OVERVIEW>
!     Calls the termination routines for all modules in the MPP package.
!   </OVERVIEW>
!   <DESCRIPTION>
!     Termination routine for the fms module. It also calls destructor routines
!      for the mpp, mpp_domains, and mpp_io modules. If this routine is called
!      more than once it will return silently. There are no arguments. 
!   </DESCRIPTION>
!   <TEMPLATE>
!     call fms_end ( )
!   </TEMPLATE>

! terminates the fms module/package
! also calls mpp destructor routines

subroutine fms_end ( )

    if (.not.module_is_initialized) return  ! return silently
!    call fms_io_exit  ! now called from coupler_end
    call mpp_io_exit
    call mpp_domains_exit
    call mpp_exit
    module_is_initialized =.false.

end subroutine fms_end
! </SUBROUTINE>


!#######################################################################
! <SUBROUTINE NAME="error_mesg">

!   <OVERVIEW>
!     Print notes, warnings and error messages; terminates program for warning 
!     and error messages. (use error levels NOTE,WARNING,FATAL, see example below)
!   </OVERVIEW>
!   <DESCRIPTION>
!     Print notes, warnings and error messages; and terminates the program for 
!     error messages. This routine is a wrapper around mpp_error, and is provided 
!     for backward compatibility. This module also publishes mpp_error,
!      <B>users should try to use the mpp_error interface</B>. 
!   </DESCRIPTION>
!   <TEMPLATE>
!     call error_mesg ( routine, message, level )
!   </TEMPLATE>

!   <IN NAME="routine"  TYPE="character" >
!     Routine name where the warning or error has occurred.
!   </IN>
!   <IN NAME="message"  TYPE="character" >
!     Warning or error message to be printed.
!   </IN>
!   <IN NAME="level"  TYPE="integer" >
!     Level of severity; set to NOTE, WARNING, or FATAL Termination always occurs 
!     for FATAL, never for NOTE, and is settable for WARNING (see namelist).
!   </IN>
!   <NOTE>
!
!     Examples:
!     <PRE>
!        use fms_mod, only: error_mesg, FATAL, NOTE

!        call error_mesg ('fms_mod', 'initialization not called', FATAL)
!        call error_mesg ('fms_mod', 'fms_mod message', NOTE)
!     </PRE>
!   </NOTE>
! wrapper for the mpp error handler
! users should try to use the mpp_error interface

 subroutine error_mesg (routine, message, level)
  character(len=*), intent(in) :: routine, message
  integer,          intent(in) :: level

!  input:
!      routine   name of the calling routine (character string)
!      message   message written to output   (character string)
!      level     set to NOTE, MESSAGE, or FATAL (integer)

    if (.not.module_is_initialized) call fms_init ( )
    call mpp_error ( routine, message, level )

 end subroutine error_mesg
! </SUBROUTINE>

!#######################################################################
! <FUNCTION NAME="fms_error_handler">

!   <OVERVIEW>
!     Facilitates the control of fatal error conditions
!   </OVERVIEW>
!   <DESCRIPTION>
!     When err_msg is present, message is copied into err_msg
!     and the function returns a value of .true.
!     Otherwise calls mpp_error to terminate execution.
!     The intended use is as shown below.
!   </DESCRIPTION>
!   <TEMPLATE>
!     if(fms_error_handler(routine, message, err_msg)) return
!   </TEMPLATE>
!   <IN NAME="routine"  TYPE="character">
!     Routine name where the fatal error has occurred.
!   </IN>
!   <IN NAME="message"  TYPE="character">
!     fatal error message to be printed.
!   </IN>
!   <OUT NAME="fms_error_handler"  TYPE="logical">
!     .true.  when err_msg is present
!     .false. when err_msg is not present
!   </OUT>
!   <OUT NAME="err_msg"  TYPE="character">
!     When err_msg is present: err_msg = message
!   </OUT>

 function fms_error_handler(routine, message, err_msg)

 logical :: fms_error_handler
 character(len=*), intent(in) :: routine, message
 character(len=*), intent(out), optional :: err_msg

 fms_error_handler = .false.
 if(present(err_msg)) then
   err_msg = message
   fms_error_handler = .true.
 else
   call mpp_error(trim(routine),trim(message),fatal)
 endif

 end function fms_error_handler
! </FUNCTION>

!#######################################################################
! <FUNCTION NAME="check_nml_error">

!   <OVERVIEW>
!     Checks the iostat argument that is returned after reading a namelist 
!     and determines if the error code is valid. 
!   </OVERVIEW>
!   <DESCRIPTION>
!     The FMS allows multiple namelist records to reside in the same file. 
!     Use this interface to check the iostat argument that is returned after 
!     reading a record from the namelist file. If an invalid iostat value 
!     is detected this routine will produce a fatal error. See the NOTE below.
!   </DESCRIPTION>
!   <TEMPLATE>
!     check_nml_error ( iostat, nml_name )
!   </TEMPLATE>

!   <IN NAME="iostat"  TYPE="integer" >
!     The iostat value returned when reading a namelist record.
!   </IN>
!   <IN NAME="nml_name"  TYPE="character" >
!     The name of the namelist. This name will be printed if an error is 
!     encountered, otherwise the name is not used.
!   </IN>
!   <OUT NAME=""  TYPE="integer" >
!     This function returns the input iostat value (integer) if it is an 
!     allowable error code. If the iostat error code is not
!     allowable, an error message is printed and the program terminated.
!   </OUT>
!   <NOTE>
!     Some compilers will return non-zero iostat values when reading through 
!     files with multiple namelist. This routine
!     will try skip these errors and only terminate for true namelist errors.
!
!     Examples
!
!       The following example checks if a file exists, reads a namelist input 
!       from that file, and checks for errors in that
!       namelist. When the correct namelist is read and it has no errors the 
!       routine check_nml_error will return zero and the while loop will exit. 
!       This code segment should be used to read namelist files. 
!       <PRE>
!          integer :: unit, ierr, io
!
!          if ( file_exist('input.nml') ) then
!              unit = open_namelist_file ( )
!              ierr=1
!              do while (ierr > 0)
!                read  (unit, nml=moist_processes_nml, iostat=io)
!                ierr = check_nml_error(io,'moist_processes_nml')
!              enddo
!              call close_file (unit)
!          endif
!       </PRE>
!   </NOTE>

!   <ERROR MSG="Unknown error while reading namelist ...., (IOSTAT = ####)" STATUS="FATAL">
!     There was an error reading the namelist specified. Carefully examine all namelist and variables 
!     for anything incorrect (e.g. malformed, hidden characters).
!   </ERROR>
!   <ERROR MSG="Unknown namelist, or mistyped namelist variable in namelist ...., (IOSTAT = ####)" STATUS="FATAL">
!     The name list given doesn't exist in the namelist file, or a variable in the namelist is mistyped or isn't a 
!     namelist variable.
!   </ERROR>

! used to check the iostat argument that is
! returned after reading a namelist
! see the online documentation for how this routine might be used
  INTEGER FUNCTION check_nml_error(IOSTAT, NML_NAME)
    INTEGER, INTENT(in) :: iostat
    CHARACTER(len=*), INTENT(in) :: nml_name

    CHARACTER(len=256) :: err_str

    IF ( .NOT.module_is_initialized) CALL fms_init()

    check_nml_error = iostat

    ! Return on valid IOSTAT values
    IF ( iostat <= 0 .OR.&
       & iostat == nml_errors%multipleNMLSinFile .OR.&
       & iostat == nml_errors%NotInFile) RETURN

    ! Everything else is a FATAL
    IF ( (iostat == nml_errors%badType1 .OR. iostat == nml_errors%badType2) .OR. iostat == nml_errors%missingVar ) THEN
       WRITE (err_str,*) 'Unknown namelist, or mistyped namelist variable in namelist ',trim(nml_name),', (IOSTAT = ',iostat,')'
       CALL error_mesg ('check_nml_error in fms_mod', err_str, fatal)
       CALL mpp_sync()
    ELSE
       WRITE (err_str,*) 'Unknown error while reading namelist ',trim(nml_name),', (IOSTAT = ',iostat,')'
       CALL error_mesg ('check_nml_error in fms_mod', err_str, fatal)
       CALL mpp_sync()
    END IF
  END FUNCTION check_nml_error
! </FUNCTION>

!-----------------------------------------------------------------------
!   private routine for initializing allowable error codes

  SUBROUTINE nml_error_init
    ! Determines the IOSTAT error value for some common Namelist errors.
    ! Also checks if the compiler returns a non-zero status if there are 
    ! multiple namelist records in a single file.
    INTEGER, PARAMETER :: unit_begin = 20, unit_end = 1024
    INTEGER :: fileunit, io_stat
    INTEGER, DIMENSION(5) :: nml_iostats
    LOGICAL :: opened

    ! Variables for sample namelists
    INTEGER :: i1, i2
    REAL :: r1, r2
    LOGICAL :: l1
    namelist /a_nml/ i1, r1
    namelist /b_nml/ i2, r2, l1
    namelist /badtype1_nml/ i1, r1
    namelist /badtype2_nml/ i1, r1
    namelist /missingvar_nml/ i2, r2
    namelist /not_in_file_nml/ i2, r2

    ! Initialize the sample namelist variables
    i1 = 1
    i2 = 2
    r1 = 1.0
    r2 = 2.0
    l1 = .false.

    ! Create a dummy namelist file
    IF ( mpp_pe() == mpp_root_pe() ) THEN
       ! Find a free file unit for a scratch file
       file_opened: DO fileunit = unit_begin, unit_end
          INQUIRE(unit=fileunit, opened=opened)
          IF ( .NOT.opened ) EXIT file_opened
       END DO file_opened

#if defined(__PGI) || defined(_CRAYFTN)
       OPEN (unit=fileunit, file='_read_error.nml', iostat=io_stat)
#else
       OPEN (unit=fileunit, status='SCRATCH', iostat=io_stat)
#endif

       ! Write sample namelist to the SCRATCH file.
       WRITE (unit=fileunit, nml=a_nml, iostat=io_stat)
       WRITE (unit=fileunit, nml=b_nml, iostat=io_stat)
       WRITE (unit=fileunit, iostat=io_stat, fmt='(/,"&badType1_nml  i1=1, r1=''bad'' /",/)')
       WRITE (unit=fileunit, iostat=io_stat, fmt='(/,"&badType2_nml  i1=1, r1=.true. /",/)')
       WRITE (unit=fileunit, iostat=io_stat, fmt='(/,"&missingVar_nml  i2=1, r2=1.0e0, l1=.true. /",/)')

       ! Rewind for reading
       rewind(unit=fileunit)

       ! Read the second namelist from the file -- check for namelist bug
       READ (unit=fileunit, nml=b_nml, iostat=nml_iostats(1))
       rewind(unit=fileunit)

       ! Read in bad type 1 --- Some compilers treat the string cast differently
       READ (unit=fileunit, nml=badtype1_nml, iostat=nml_iostats(2))
       rewind(unit=fileunit)

       ! Read in bad type 2
       READ (unit=fileunit, nml=badtype2_nml, iostat=nml_iostats(3))
       rewind(unit=fileunit)

       ! Read in missing variable/misstyped
       READ (unit=fileunit, nml=missingvar_nml, iostat=nml_iostats(4))
       rewind(unit=fileunit)

       ! Code for namelist not in file
       READ (unit=fileunit, nml=not_in_file_nml, iostat=nml_iostats(5))

       ! Done, close file
       CLOSE (unit=fileunit)

       ! Some compilers don't handle the type casting as well as we would like.
       IF ( nml_iostats(2) * nml_iostats(3) .EQ. 0 ) THEN
          IF ( nml_iostats(2) .NE. 0 .AND. nml_iostats(3) .EQ. 0 ) THEN
             nml_iostats(3) = nml_iostats(2)
          ELSE IF ( nml_iostats(2) .EQ. 0 .AND. nml_iostats(3) .NE.0 ) THEN
             nml_iostats(2) = nml_iostats(3)
          ELSE 
             nml_iostats(2) = nml_iostats(4)
             nml_iostats(2) = nml_iostats(4)
          END IF
       END IF
    END IF

    ! Broadcast nml_errors
    CALL mpp_broadcast(nml_iostats,5,mpp_root_pe())
    nml_errors%multipleNMLSinFile = nml_iostats(1)
    nml_errors%badType1 = nml_iostats(2)
    nml_errors%badType2 = nml_iostats(3)
    nml_errors%missingVar = nml_iostats(4)
    nml_errors%NotInFile = nml_iostats(5)

    do_nml_error_init = .false.
  END SUBROUTINE nml_error_init

!#######################################################################


! <FUNCTION NAME="string_array_index">

!   <OVERVIEW>
!     match the input character string to a string
!     in an array/list of character strings
!   </OVERVIEW>
!   <DESCRIPTION>
!      Tries to find a match for a character string in a list of character strings.
!      The match is case sensitive and disregards blank characters to the right of
!      the string. 
!   </DESCRIPTION>
!   <TEMPLATE>
!      string_array_index ( string, string_array [, index] )
!   </TEMPLATE>

!   <IN NAME="string"  TYPE="character(len=*), scalar" >
!     Character string of arbitrary length.
!   </IN>
!   <IN NAME="string_array"  TYPE="character(len=*)" DIM="(:)">
!     Array/list of character strings.
!   </IN>
!   <OUT NAME="index"  TYPE="integer" >
!     The index of string_array where the first match was found. If
!            no match was found then index = 0.
!   </OUT>
!   <OUT NAME="string_array_index"  TYPE="logical" >
!     If an exact match was found then TRUE is returned, otherwise FALSE is returned.
!   </OUT>
!   <NOTE>
!     Examples
!      <PRE>
!       string = "def"
!       string_array = (/ "abcd", "def ", "fghi" /)

!       string_array_index ( string, string_array, index )

!       Returns: TRUE, index = 2
!      </PRE>
!   </NOTE>
! match the input character string to a string
! in an array/list of character strings

function string_array_index ( string, string_array, index ) result (found)
character(len=*),  intent(in)  :: string, string_array(:)
integer, optional, intent(out) :: index
logical :: found
integer :: i

! initialize this function to false
! loop thru string_array and exit when a match is found

  found = .false.
  if (present(index)) index = 0

  do i = 1, size(string_array(:))
    ! found a string match ?
    if ( trim(string) == trim(string_array(i)) ) then
         found = .true.
         if (present(index)) index = i
         exit
    endif
  enddo

end function string_array_index
! </FUNCTION>

!#######################################################################

! <FUNCTION NAME="monotonic_array">

!   <OVERVIEW>
!     Determines if a real input array has monotonically increasing or
!     decreasing values.
!   </OVERVIEW>
!   <DESCRIPTION>
!     Determines if the real input array has monotonically increasing or
!     decreasing values.
!   </DESCRIPTION>
!   <TEMPLATE>
!     monotonic_array ( array [, direction] )
!   </TEMPLATE>

!   <IN NAME="array"  TYPE="real" DIM="(:)">
!     An array of real values. If the size(array) < 2 this function
!     assumes the array is not monotonic, no fatal error will occur.
!   </IN>
!   <OUT NAME="direction"  TYPE="integer" >
!     If the input array is:
!                >> monotonic (small to large) then direction = +1.
!                >> monotonic (large to small) then direction = -1.
!                >> not monotonic then direction = 0. 
!   </OUT>
!   <OUT NAME="monotonic_array"  TYPE="logical" >
!     If the input array of real values either increases or decreases monotonically
!      then TRUE is returned, otherwise FALSE is returned. 
!   </OUT>
! determines if the real input array has
! monotonically increasing or decreasing values

function monotonic_array ( array, direction )
real,    intent(in)            :: array(:)
integer, intent(out), optional :: direction
logical :: monotonic_array
integer :: i

! initialize
  monotonic_array = .false.
  if (present(direction)) direction = 0

! array too short
  if ( size(array(:)) < 2 ) return

! ascending
  if ( array(1) < array(size(array(:))) ) then
     do i = 2, size(array(:))
       if (array(i-1) < array(i)) cycle
       return
     enddo
     monotonic_array = .true.
     if (present(direction)) direction = +1

! descending
  else
     do i = 2, size(array(:))
       if (array(i-1) > array(i)) cycle
       return
     enddo
     monotonic_array = .true.
     if (present(direction)) direction = -1
  endif

end function monotonic_array
! </FUNCTION>

end module fms_mod
! <INFO>
!   <BUG>              
!     Namelist error checking may not work correctly with some compilers.
!
!     Users should beware when mixing Fortran reads and read_data calls. If a
!     Fortran read follows read_data and namelist variable read_all_pe = FALSE
!     (not the default), then the code will fail. It is safest if Fortran reads 
!     precede calls to read_data.
!   </BUG>
!   <ERROR MSG="unexpected EOF" STATUS="FATAL">
!     An unexpected end-of-file was encountered in a read_data call.
!     You may want to use the optional end argument to detect the EOF. 
!   </ERROR>
!   <NOTE>
!     1) If the <B>MPP</B> or <B>MPP_DOMAINS</B> stack size is exceeded the
!     program will terminate after printing the required size. 
!   
!     2) When running on a very small number of processors or for high
!     resolution models the default domains_stack_size will
!     probably be insufficient. 
!
!     3) The following performance routines in the <B>MPP</B> module are published by this module.
!<PRE>
!        mpp_clock_id, mpp_clock_begin, mpp_clock_end
!</PRE>
!        and associated parameters that are published:
!<PRE>
!        MPP_CLOCK_SYNC, MPP_CLOCK_DETAILED, CLOCK_COMPONENT, CLOCK_SUBCOMPONENT,
!        CLOCK_MODULE_DRIVER, CLOCK_MODULE, CLOCK_ROUTINE, CLOCK_LOOP, CLOCK_INFRA
!</PRE>
!
!     4) Here is an example of how to time a section of code.<BR/>
!<PRE>
!          use fms_mod, only: mpp_clock_id, mpp_clock_begin, &
!                             mpp_clock_end. MPP_CLOCK_SYNC, &
!                             CLOCK_MODULE_DRIVER
!          integer :: id_mycode
!
!          id_mycode = mpp_clock_id ('mycode loop', flags=MPP_CLOCK_SYNC, grain=CLOCK_MODULE_DRIVER)
!          call mpp_clock_begin (id_mycode)
!                        :
!                        :
!           ~~ this code will be timed ~~ 
!                        :
!                        :
!          call mpp_clock_end (id_mycode)
! </PRE>
!        Note: <TT>CLOCK_MODULE_DRIVER</TT> can be replaced with
!        CLOCK_COMPONENT, CLOCK_SUBCOMPONENT, CLOCK_MODULE_DRIVER, CLOCK_MODULE, CLOCK_ROUTINE,
!        CLOCK_LOOP, or CLOCK_INFRA.
!        
!   </NOTE>
!   <FUTURE>           
!     NetCDF facilities for reading and writing restart files and (IEEE32) 
!       data files.
!    </FUTURE>
!    <FUTURE>
!     May possible split the FMS module into two modules. 
!
!      i.general utilities (FMS_MOD) <BR/>
!     ii.I/O utilities (FMS_IO_MOD) 
!    </FUTURE>
! </INFO>