DragonFly On-Line Manual Pages
fpp(1) DragonFly General Commands Manual fpp(1)
NAME
fpp - the Fortran language preprocessor for FORTRAN 77 and Fortran 90.
SYNOPSIS
fpp [ options ] [ input-file [ output-file ] ]
DESCRIPTION
fpp is the preprocessor for FORTRAN 77 and Fortran 90. fpp
optionally accepts two filenames as arguments. input-file and
output-file are, respectively, the input file read and the output
file written by the preprocessor. By default standard input and output
are used. fpp should be used instead of the cpp preprocessor with the
Sun FORTRAN 77 compiler.
OPTIONS
-c_com={yes|no}
By default, C style comments are recognized. Turn this off by
specifying -c_com=no
-Dname Define the preprocessor variable name as 1 (one). This is the
same as if a -Dname=1 option appeared on the fpp command line,
or as if a
#define name 1
line appeared in the source file, which is processed by fpp.
-Dname=def
Define name as if by a #define directive. This is the same as
if a
#define name def
line appeared in the source file that fpp is processing. The -D
option has lower precedence than the -U option. That is, if the
same name is used in both a -U option and a -D option, the name
will be undefined regardless of the order of the options.
-fixed Assumes fixed format input source.
-free Assumes free format input source.
-Idirectory
Insert directory into the search path for #include files with
names not beginning with `/'. directory is inserted ahead of
the standard list of ``include'' directories. Thus, #include
files with names enclosed in double-quotes (") are searched for
first in the directory of the file with the #include line, then
in directories named with -I options, and lastly, in directories
from the standard list. For #include files with names enclosed
in angle-brackets (<>), the directory of the file with the
#include line is not searched.
-M Generate a list of makefile dependencies and write them to the
standard output. This list indicates that the object file which
would be generated from the input file depends on the input
file as well as the include files referenced.
-macro={yes|no_com|no}
By default, macros are expanded everywhere. Turn off macro
expansion in comments by specifying -macro=no_com and turn off
macro expansion all together by specifying -macro=no
-P Do not put line numbering directives to the output file. This
directive appears as
#line-number file-name
-Uname Remove any initial definition of name, where name is a fpp
variable that is predefined by a particular preprocessor. Here
is a partial list of symbols that may be predefined, depending
upon the architecture of the system:
Operating System: unix, __unix, and__SVR4
Hardware: sun, __sun, sparc, and__sparc
-undef Remove initial definitions for all predefined symbols.
-w0 Don't output warnings from fpp to stderr.
-Xu Convert upper-case letters to lower-case, except within
character-string constants. The default is to not convert upper-
case letters to lower-case.
-Xw For fixed form source files (See below) fpp assumes that the
symbol ' ' (space) is insignificant. By default for this form
the 'space' symbol is the delimiter of tokens.
-Ydirectory
Use the specified directory in place of the standard list of
directories when searching for files.
fpp also understands some FORTRAN 77 compiler options (See f77(1)):
-e Accept extended source lines, up to 132 characters long.
-w Do not output warnings to stderr.
USAGE
Source files
fpp operates on both fixed and free form source files. Files with '.F'
extension are assumed to be in fixed form, and files with '.F90'
extensions (and all others) are assumed to be in free form by default.
There is the '-fixed' option for using fixed form in Fortran 90. fpp
recognizes the tab format of a source line when in fixed mode.
A source file may contain fpp tokens. fpp tokens are close to those of
Fortran. They are:
- fpp directive names.
- symbolic names including Fortran keywords. fpp permits
all symbols in names that Fortran does.
- constants. Integer, real, double and quadruple precision,
binary, octal, hexadecimal including alternate notation,
character and hollerith.
- comments. There are Fortran comments and fpp comments.
- others. Special characters, space, tab, newline, etc.
Output
Output consists of a modified copy of the input, plus lines of the
form:
#line_number file_name
inserted to indicate the original source line number and filename of
the output line that follows. There is the '-P' option (See above)
which disables the generation of these lines.
Directives
Syntax and semantics of fpp directives are the same as cpp directives
(See cpp(1)).
All fpp directives start with the hash symbol (#) as the first
character on a line. White space (SPACE or TAB characters) can appear
after the initial '#' for proper indentation. The directives can be
divided into the following groups:
- macro definitions;
- conditional source code selection;
- inclusion of external files;
- line control.
Macro definition.
The #define directive is used to define both simple string variables
and more complicated macros:
#define name token-string
This is the definition of a fpp variable. Wherever 'name' appears in
the source lines following the definition, 'token-string' will be
substituted for 'name'.
#define name(argument [, argument] ... ) token-string
This is the definition of a function-like macro. Occurrences of the
macro 'name' followed by the comma-separated list of arguments within
parentheses are substituted by the token string produced from the macro
definition. Every occurrence of an argument identifier from the macro
definition's arguments list is substituted by the token sequence
representing the corresponding macro actual argument.
In these definitions, spaces between the macro name and the '(' symbol
are prohibited to prevent the directive being interpreted as a fpp
variable definition with the rest of the line beginning with the '('
symbol being interpreted as a token-string.
#undef name
Remove any definition for 'name' (produced by 'D' options, #define
directives or by default). No additional tokens are permitted on the
directive line after the name.
Including External Files.
There are two forms of file inclusion:
#include "filename"
#include <filename>
Read in the contents of filename at this location. The lines read in
from the file are processed by fpp as if it were a part of the current
file.
When the <filename> notation is used, filename is only searched for
in the standard ``include'' directories. See the 'I' and 'Y' options
above for more detail. No additional tokens are permitted in the
directive line after the final `"' or `>'.
Line control.
#line-number "filename"
Generate line control information for the next pass of the compiler.
The integer-constant is interpreted as the line number of the next
line and the filename is interpreted as the name of the file from
where it comes. If "filename" is not given, the current filename is
unchanged.
Conditional selection of source text.
There are two forms of conditional selection of source text
1)
#if condition_1
block_1
#elif condition_2
block_2
#else
block_n
#endif
2)
#ifdef name
block_1
#elif condition
block_2
#else
block_n
#endif
or
#ifndef name
block_1
#elif condition
block_2
#else
block_n
#endif
else- and elif-part are optional. There may be more than one elif-
part. Condition is an expression involving fpp constants, macros and
intrinsic functions. Condition expressions are similar to cpp
expressions, and may contain any cpp operations and operands with the
exception of c long, octal and hexadecimal constants. Additionally, fpp
will accept and evaluate Fortran logical operations .NOT. .AND. .OR.
.EQV. .NEQV. .GT. .LT. .LE. .GE. etc. and logical constants .TRUE.
.FALSE.
Details
Scope of macro or variable definitions.
The scope of a definition begins from the place of its definition and
encloses all the source lines (and source lines from included files)
from that definition line to the end of the current file.
There are the following exceptions to the scope effected by an fpp
definition:
- files included by Fortran INCLUDE statements;
- fpp and Fortran comments;
- IMPLICIT single letter specifications;
- FORMAT specifications;
- numeric, typeless and character constants.
The scope of the macro effect can be limited by means of the #undef
directive.
End of macro definition
Macro definition can be of any length and is limited only by the
'newline' symbol. A Macro can be defined in multiple lines. A Macro can
be continued to the next line with the insertion of '\'. So, the
occurrence of a 'newline' without a macro-continuation signifies the
end of the macro definition.
For example:
#define long_macro_name(x,\
y) x*y
Function-like macro definition
The number of macro call arguments should be the same as the number of
arguments in the corresponding macro definition. An error is flagged if
they don't.
Cancelling macro definitions of both kinds
#undef name
After this directive, 'name' would not interpreted by fpp as a macro
or variable name. If this name has not been defined earlier as a macro
name, then the given directive has no effect
Conditional source code selection
- Constant-expression
Subsequent lines up to the matching #else, #elif, or #endif directive,
appear in the output only if their constant-expression yields a true
value.
The lines following the #elif directive appear in the output only if
all of the following conditions hold:
- The constant-expression in the preceding #if directive
evaluated to .FALSE. or the name in the preceding #ifdef
directive is not defined or the name in the preceding
#ifndef directive is defined.
- The constant-expression in all intervening #elif
directives evaluated to .FALSE.
- The current constant-expression evaluates to .TRUE.
If the constant-expression evaluates to .TRUE., subsequent #elif
and #else directives are ignored up to the matching #endif. Any
constant-expression allowed in an #if directive is allowed in an
#elif directive.
The intrinsic function `defined' can be used in a constant-expression
also.
The following items are permitted:
- C language operations: <, >, ==, !=, >=, <=, +, -, /, *,
%, <<, >>, &, ~, |, &&, || They are interpreted by fpp
in accordance to the C language semantics (this facility
is provided for compatibility with "old" Fortran programs
using cpp)
- Fortran language operations: .AND., .OR., .NEQV., .XOR.,
.EQV., .NOT. , .GT., .LT., .LE., .GE., .NE., .EQ., **
(power).
- Fortran logical constants: .TRUE. , .FALSE.
Only these items, integer constants, and names can be used
within a constant-expression. Names which have not been defined
with the help of the 'D' option, a #define directive or by
default, get 0 as the value. The C operation '!=' (not equal)
can be used in #if or #elif directive, but NOT in #define
directive, where the symbol '!' is considered as the Fortran
comment symbol.
#ifdef name
Subsequent lines up to the matching #else, #elif, or #endif
appear in the output only if the name has been defined, either
by a #define directive or by the 'D' option, and in the absence
of an intervening #undef directive. No additional tokens are
permitted on the directive line after name.
#ifndef name
Subsequent lines up to the matching #else, #elif, or #endif
appear in the output only if name has not been defined, or if
its definition has been removed with an #undef directive. No
additional tokens are permitted on the directive line after
name.
#elif constant-expression .
Any number of #elif directives may appear between an #if,
#ifdef, or #ifndef directive and a matching #else or #endif
directive.
#else This inverts the sense of the conditional directive otherwise in
effect. If the preceding conditional would indicate that lines
are to be included, then lines between the #else and the
matching #endif are ignored. If the preceding conditional
indicates that lines would be ignored, subsequent lines are
included in the output. Conditional directives and
corresponding #else directives can be nested.
#endif End a section of lines begun by one of the conditional
directives #if, #ifdef, or #ifndef. Each such directive must
have a matching #endif.
Including External Files
Is the same as it is for cpp. Files are searched as follows:
for #include "file_name":
- in the directory, in which the processed file has been
found;
- in the directories specified by the -I option;
- in the default directory.
for #include <file_name>:
- in the directories specified by the -I option;
- in the default directory.
fpp directives (beginning with the # symbol in the first position of
lines) can be placed anywhere in a source code, in particular before a
Fortran continuation line. The only exception is the prohibition of
fpp directives within a macro call divided on several lines by means of
continuation symbols.
Comments
fpp permits comments of two kinds:
1) Fortran language comments. A source line containing one of the
symbols 'C', 'c', '*', 'd' or 'D' in the first position, is considered
as a comment line. Within such lines macro expansions are not
performed. The '!' symbol is interpreted as the beginning of a comment
extending to the end of the line. The only exception is the case when
this symbol occurs within a constant-expression in #if and #elif
directives (See above).
2) fpp comments enclosed in the '/*' and '*/' parasymbols. They are
excluded from the output and macro expansions are not performed within
these symbols. fpp comments can be nested and for each parasymbol '/*'
there must be a corresponding parasymbol '*/'. fpp comments are
suitable for excluding the compilation of large portions of source
instead of commenting every line with Fortran comment symbols.
Intrinsic functions
The intrinsic function
defined(name) or defined name
Returns:
.TRUE. - if name is defined as a macro.
.FALSE.- if the name is not defined.
Macro expansion
If, during expansion of a macro, the column width of a line exceeds
column 72 (for the fixed format) or column 132 (for the free format),
fpp inserts appropriate continuation lines.
In the fixed form there is limitation on macro expansions in label
fields (positions 1-5):
- a macro call (together with possible arguments) should
not extend more than the column 5 position;
- a macro call whose name begins with one of the Fortran
comment symbols is considered as a part of a comment;
- a macro expansion may produce a text extending beyond the
column 5 position. In such a case a warning will be
issued.
In the fixed form when the '-Xw' option has been specified an ambiguity
may appear if a macro call occurs in a statement position and a macro
name begins or coincides with a Fortran keyword. For example, in the
following text:
#define callp(x) call f(x)
call p(0)
fpp can not determine with certainty how to interpret the 'call p'
token sequence. It could be considered as a macro name. The current
implementation does the following:
- the longer identifier is chosen (callp in this case);
- from this identifier the longest macro name or keyword is
extracted;
- if a macro name has been extracted a macro expansion is
performed. If the name begins with some keyword fpp
outputs an appropriate warning;
- the rest of the identifier is considered as a whole
identifier.
In the above example the macro expansion would be performed and the
following warning would be output:
warning: possibly incorrect substitution of macro callp
It should be noted that this situation appears only when preprocessing
a fixed format source code and when the space symbol is not interpreted
as a token delimiter. It should be said also that if a macro name
coincides with a keyword beginning part, as in the following case:
#define INT INTEGER*8
INTEGER k
then in accordance with the described algorithm, the INTEGER keyword
will be found earlier than the INT macro name. Thus, there will be no
warning when preprocessing such a macro definition.
DIAGNOSTICS
There are three kinds of diagnostic messages:
- warnings. preprocessing of source code is continued and
the return value remains to be 0.
- errors. fpp continues preprocessing but sets the return
code to a nonzero value, namely number of errors.
- fatal error. fpp cancels preprocessing and returns a
nonzero return value.
The messages produced by fpp are intended to be self-explanatory. The
line number and filename where the error occurred are printed along
with the diagnostic.
SEE ALSO
cpp(1), f77(1), f90(1)
19 Aug 1996 fpp(1)