to_f90

Takes Fortran 77 code in standard format and makes some changes to produce free-format Fortran 90 code.

N.B. It expects STANDARD F77 code. Non-standard extensions such as DO .. END DO (i.e. no label) or in-line comments may cause havoc!

fpm usage

I have taken the liberty of making some minor changes and turning Alan Miller's to_f90 into a fpm package.

These changes were:

• split the original single file into a standalone program (./app/to_f90.f90) and two module files (./src/implicit.f90 and ./src/interfaced.f90)

• the latter module (interfaced) contains procedures that were previously external to the main program, but with explicit interfaces. I removed the interfaces from the main program, moved the procedures to this new module, and then use'd the module in the main program. Could very well be a glaring oversight from me, but I see no reason for not doing this?

• all files have been polished using

  nagfor =polish 
    -alter_comments -array_constructor_brackets=Square -blank_line_after_decls -free -indent=2 
    -indent_comment_marker -indent_comments -keep_blank_lines -keep_comments -kind_keyword=Remove 
    -kwcase=C -margin=0 -name_scopes=Insert -terminate_do_with_enddo -wrap_comments 
    *.f90
  

  then I manually added spaces before numbered labels, to still allow convenient code folding in an IDE

You can build the package like so (see fpm's documentation for more options)

fpm build --profile release

And then install it, for effortless use right from the command line, like so

fpm install --profile release

Original in-source documentation:

Changes included are:

• C or c in column 1 replaced with !

• Continuation denoted by a character in column 6 replaced with & at the end of the previous line.

• Indenting of code for DO-loops and IF blocks.

• END of program unit replaced by END SUBROUTINE (/PROGRAM/FUNCTION) name

• Fortran `keywords' are in upper case, all other words other than those in character strings are converted to lower case.

• .LT., .EQ., etc. replaced with <, ==, etc.

• Labels removed from DO loops; all of which will end with END DO.

• If labels are not referenced, they are removed.

• Short continued lines are adjoined to the previous line.

• ENDIF, ELSEIF & GOTO split into separate words.

• 3-way arithmetic IF constructs are converted to IF .. ELSE IF form.

• Embedded blanks are removed from numbers in DATA statements.

• INTENT declarations are added for dummy arguments.

• Some GO TOs are converted to CYCLE or EXIT.

• Converts CHARACTER * to CHARACTER (LEN=xx) ::.

• Converts computed GO TOs to SELECT CASE.

To be done:

• DATA statements to be replaced by assignments on the declaration line.

• IMPLICIT NONE statements to be included.

• Declaration of types of unlisted variables.

• Functions to be converted to ELF90 form, i.e. REAL FUNCTION XYZ(arg) converted to FUNCTION xyz(arg) RESULT(fn_val).

Known problems

• Cannot handle character strings or names broken at the end of lines.

• No attempt to convert BLOCKDATA, COMMON or EQUIVALENCE.

• Does not convert Hollerith strings, e.g. 31HTHIS IS A COMMENT ...

• May do the wrong thing if variable names start with IF or end with DO.

• INTENTs are sometimes wrong. In particular, INTENT(IN) arguments are often shown as INTENT(IN OUT).

• Cannot handle comment lines in the middle of continued instructions.

• Can handle character*(*) str but not character str*(*).

The default extension for the name of the input file is .for; this can be over-ruled by giving the full name (e.g. myprog.f77). The output file name will be the input name (and directory) with extension .f90.

Changelog

• Added conversion of enddo to END DO - 13 March 1997

• Corrected bug which occurred when an arithmetic IF within a DO-loop involved a jump to the end of the DO-loop - 17 August 1997.

• ELSEIF, ENDIF & ELSEIF were being split into 2 separate words, and then the last letter converted back to lower case - corrected 17 August 1997.

• Corrected bug which occurred when .LT. (or other comparison) had a blank before and/or after, followed on the same line by a text string, followed by a Fortran word such as THEN or GO TO - 8 December 1997.

• Added (LEN=1) after CHARACTER if length not specified - 9 December 1997.

• Embedded blanks are removed from numerical constants in DATA statements. Added 9 December 1997.

• Added INTENTs and TYPE declarations for dummy arguments - 23 December 1997.

• Corrected problem when DO statement contains a comma immediately after DO, and improved the detection of INTENTs when a dummy argument appears in an IF-expression. Added extra indentation on continuation lines to improve readability - 13 January 1998

• Corrected a bug which could occur when the last type declaration was matched to a dummy variable and the line deleted - 5 June 1998

• Corrected jumps out of inner nested DO loops, and replaced GO TOs, out of DO loops to the next executable line, with EXIT - 8 June 1998

• Added conversion of CHARACTER * to CHARACTER (LEN=xx) :: including CHARACTER*10 a, d, c*50, d - 21 June 1998.

• Corrected for case of final command of a DO loop which is not CONTINUE and which flows onto the next line - 29 June 1998.

• Added conversion of computed GO TOs to SELECT CASE form, and fixed problem when a CHARACTER dummy variable had * as its last dimension - 26 November 1998.

• Fixed problems when the dimensions of a dummy variable involved another dummy variable, e.g. wk(nrow*(ncols+1)) - 25 December 1998

• Added date & time stamp - 27 January 1999

• Finally fixed the problems with CYCLE & EXIT, I hope! - 2 February 1999

• Fixed a problem when a type declaration was continued and the next line declared the type(s) of dummy arguments - 3 February 1999

• Added conversion of PARAMETER statements from PARAMETER (name1=v1, .. ) to TYPE1, PARAMETER :: name1=v1 - 8 February 1999

• Added EQV to the list of FORTRAN 'words' - 11 February 1999

• Partially corrected problems with the construct: IF (condition) GO TO (10, 20, .. ..., 99), next i.e. with IF & computed GOTO in the same statement (without a THEN), and continued onto the next line.

  Also changed a DATA statement to a PARAMETER statement to make the code compatible with ELF90 (Thanks to David Ormerod) - 20 May 1999

• Added test for existence of source file. Program crashed previously if the file was not found - 3 August 1999

• Corrected SUBROUTINE fix_3way_IF so that it does not interpret IFIX (or similar) as an IF - 23 January 2000.

• At last fixed up strings in quotes which flowed from one line to the next - 24 January 2000

• Fixed an error which sometimes caused GOTOs to be wrongly converted to CYCLE - 21 March 2000

• Latest revision - 21 March 2000

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Author - Alan Miller (amiller @ bigpond.net.au)

WWW-page: https://wp.csiro.au/alanmiller/