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https://github.com/rtoy/f2cl

F2cl - A Fortran 77 to Common Lisp translator
https://github.com/rtoy/f2cl

fortran lisp translation

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F2cl - A Fortran 77 to Common Lisp translator

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README 

        
# Welcome to f2cl - a Fortran to Common Lisp Translator



Contained in this directory are source code files and some documentation.

The translator is written in Common Lisp making installation simple.



# Installation



If this has been extracted as a part of CLOCC, the way to build f2cl

is to simply run "make system" from a shell, as is usual with CLOCC

packages.



A second method is to use defsystem from CLOCC.  Then load

`f2cl.system`, and then finally run `(mk:oos "f2cl" :compile)`.  



A third method is to use asdf.  You can load `f2cl.asd` and run

`(asdf:oos 'asdf:load-op :f2cl)`.



Finally, a fourth method, if you have none of the above, is to

manually run everything as follows:



1. Start your favorite Common Lisp implementation use the function

   `compile-file` to compile each of the source files:



		f2cl0.l

		f2cl1.l

		f2cl2.l

		f2cl3.l

		f2cl4.l

		f2cl5.l

		f2cl6.l

		f2cl7.l

		macros.l



2. Load up all of the files



        (load "f2cl0.l")

        (load "f2cl1.l")

        (load "f2cl2.l")

        (load "f2cl3.l")

        (load "f2cl4.l")

        (load "f2cl5.l")

        (load "f2cl6.l")

        (load "f2cl7.l")

	    (load "macros.l")



   to load all the compiled files.



# Usage



## Converting Fortran Code



To use f2cl:

```

(f2cl:f2cl "/fortran.f")

```

will convert the file `/fortran.f` to Lisp code and places the

result in the file `/fortran.lisp`.



Alternatively,

```

(f2cl:f2cl-compile "/fortran.f")

```

will also run `compile-file` on the Lisp file so you can load it

directly into your lisp.



For those anxious to use the translator without studying the documentation

here is a short list of restrictions that may result in obscure errors:

 - input code is assumed to be valid Fortran 77

 - no tabs are permitted in the source,

 - $comments should only be turned on if the Fortran code has comments

   exclusively within subroutines,

 - linebreaks must occur within whitespace,

 - spaces are required to separate symbols.



Note also that an intermediate file called "prep.tmp" is produced by the

preprocessing stage of the translation.



### Options



These are the options available to `f2cl:f2cl` and `f2cl:f2cl-compile`



* `:OUTPUT-FILE`             

	File to contain Lisp code



* `:VERBOSE`                

	Verbose output. Default = NIL.  Mostly for debugging.



* `:PRUNE-LABELS`           

	Prune unused labels. Default = NIL.



* `:INCLUDE-COMMENTS`       

	Include Fortran comments in the Lisp output.

        Default = NIL



* `:AUTO-SAVE`              

	Variables in DATA statements are automatically SAVE'd. Default

	= T.



* `:RELAXED-ARRAY-DECLS`      

	Declarations of array sizes are relaxed in formal

        parameters to functions. That is, any array

        length declarations (except lower limits) are

        ignored if possible, like old Fortran used

        to. Default = T.



* `:COERCE-ASSIGNS`  

	If `T` or `:ALWAYS`, all assignment statements automatically

        coerce the RHS to the appropriate type for the assignment.  If

        `NIL` or `:NEVER`, coercion never happens.  If `:AS-NEEDED`, f2cl

        applies coercion if it thinks it is needed.  Default =

        `:AS-NEEDED`.



* `:EXTENSION`                 

	The extension to use for the output file, if needed.  Defaults

        to `*DEFAULT-LISP-EXTENSION*` or "lisp".



* `:KEEP-TEMP-FILE`

	If `T`, the temporary file is not deleted.  This is mostly for

	debugging f2cl. Default = `NIL`.



* `:ARRAY-TYPE`  

	The type of array f2cl should use.  Should be `:simple-array` or

        `:array`.  For some compilers, there can be significant speed up

        if the array can be declared as simple-arrays.  But this is

        incompatible with array-slicing, so care must be used if you

        choose `:simple-array`. Default = `:array.`



* `:ARRAY-SLICING`  

	When non-`NIL`, f2cl assumes that, whenever we do an array

        reference in a call to a subroutine or function, we are really

        passing a subarray to the routine instead of just the single

        value, unless f2cl knows the function takes a scalar arg that

        is not modified.  Default = `T`.



* `:PACKAGE`  

	A string or symbol specifying what package the resulting code

        should be in. (Basically puts a `(in-package 
)` at the top.)

        Default is "COMMON-LISP-USER".



* `:DECLAIM` 

	Declaim compilation options (Basically puts a `(declaim )` at the top.)  Default is none.



* `:DECLARE-COMMON`  

	When non-`NIL`, any structures definitions for common blocks are

        defined when converting this file. Otherwise, the structures

        for the common blocks are expected to be defined elsewhere.

        This should be used only once for one subprogram that will be

        used to define the common block.  See below for more

        information. Default is `NIL`.



* `:FLOAT-FORMAT`              

	Float format to use when printing the result.  Default is

        `*READ-DEFAULT-FLOAT-FORMAT*`



* `:COMMON-AS-ARRAY`  

	Instead of defining a common block as a structure with the

	same slot names as variables in the common block, the common

	block is defined as a set of arrays.  The actual common block

	variables are defined as offsets into these arrays.  For more

	information see below.  This mimics the memory layout of how

	Fortran treats common blocks.  Default = `NIL`.



# Using Converted Code



Once you've converted the code, you do not need to load up all of f2cl

to use the converted code.  In fact, you only need f2cl0.l and

macros.l to define the necessary packages and functions used by the

converted code.  Actually, you really only need the defpackage for

f2cl-lib in f2cl0.l.



# Issues



For a more detailed list of issues and notes, see src/NOTES.



We highlight just a few issues here.



## Block data statements



In Fortran, block data statments are used to initialize common

blocks.  Since Fortran executables are loaded and run just once,

this is not a problem.  However, in Lisp, this might not be true,

and you may want to run the main program many times.  Thus, it is

up to you to run the block data initializer at the right time, as

needed.  f2cl cannot know when and where to call the initializer.



## Common blocks  

F2cl converts common blocks to structures.  However, common blocks

may be referenced in several different files, so the user must

tell f2cl when to define the structure.  Use the :declare-common

parameter to tell f2cl to define the structure. This should be

done exactly once for each common block that is defined.  This

should also be done for the first file that is compiled and

loaded, so that subsequent files know about the definition.



In addition, there is another option, :common-as-array.  This

changes how f2cl handles common blocks.   A rather common use of

common blocks has the same common block using different variable

names.  For example, one routine might have

```

        COMMON /foo/ a(10), b, i(4)

```



and another might say



```

        COMMON /foo/ b(9), c, d, j(2), k(2)

```



In Fortran, this is perfectly acceptable.  Normally, f2cl expects

all common blocks to use the same variable names, and then f2cl

creates a structure for the common block using the variable names

as the names of the slots.  However, for a case like the above,

f2cl gets confused.  Hence, :common-as-array.  We treat the common

block as an array of memory.  So this gets converted into a

structure somewhat like

```

        (defstruct foo

          (part-0 (make-array 11 :element-type 'real))

          (part-1 (make-array 4 :element-type 'integer4)))

```

(In a more general case, we group all contiguous variables of the

same type into one array.  f2cl and Lisp cannot handle the case

where a real and integer value are allocated to the same piece of

memory.)



Then in the individual routines, symbol-macrolets are used to

create accessors for the various definitions.  Hence, for the

second version, we would do something like

```

          (symbol-macrolet 

            (b (make-array 9 :displaced-to 

                           (foo-part-0 *foo*)

                           :diplaced-offset 0))

            (c (aref (foo-part-0 *foo*) 9))

            (d (aref (foo-part-0 *foo*) 10))

            (j (make-array 2 :displaced-to

                           (foo-part-1 *foo*)

                           :displaced-offset 0))

            (k (make-array 2 :displaced-to

                           (foo-part-1 *foo*)

                           :displaced-offset 2))

            ...)

```

Thus, we access the right parts of the common block, independent

of the name.  Note that this has a performance impact since we

used displaced arrays.

  



## Conversion order

While not necessary, f2cl can do a significantly better job in

generating code if the functions are compiled in the correct

order.  This means any function, F, that is called by another

function, G,  should compiled first.  In this way, f2cl can

determine the calling conventions for F, and generate the

appropriate call for F in G.  This is important if F takes an

array argument and G passes a slice of an array to F, or

conversely if F takes a simple variable, and G calls F with an

array reference.  



If this is not done, the user may have to modify either the

Fortran code or the resulting Lisp code to pass arguments

correctly.  



F2cl cannot always determine whether a slice of an array should be

used or just the single element.



See also the file src/NOTES which contains a change log.  But there

are also various notes about about restrictions and enhancements on

various features supported by f2cl.



# Acknowledgments



The translator was written by Kevin Broughan and Diane Koorey Willcock

at the University of Waikato. Reports should be sent to

[email protected] and should include examples of Fortran code which

fails to translate or which translates incorrectly.



Major changes have be written by Raymond Toy and the entire translator

is now part of CLOCC, with permission from Kevin Broughan.  Send bug

reports and other comments to http://clocc.sourceforge.net.



The code is also placed under the GPL, by permission of Kevin

Broughan.  The exception is macros.l which is released under the LGPL

so that it can be incorporated into other packages.