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Diffstat (limited to 'gcc/fortran/gfortran.texi')
| -rw-r--r-- | gcc/fortran/gfortran.texi | 92 |
1 files changed, 91 insertions, 1 deletions
diff --git a/gcc/fortran/gfortran.texi b/gcc/fortran/gfortran.texi index 0278bd6..e65c2de 100644 --- a/gcc/fortran/gfortran.texi +++ b/gcc/fortran/gfortran.texi @@ -1470,6 +1470,7 @@ compatibility extensions along with those enabled by @option{-std=legacy}. * %LOC as an rvalue:: * .XOR. operator:: * Bitwise logical operators:: +* Extended I/O specifiers:: @end menu @node Old-style kind specifications @@ -2605,6 +2606,95 @@ Here is the mapping of logical operator to bitwise intrinsic used with @item @code{.EQV.} @tab @code{@ref{NOT}(@ref{IEOR})} @tab complement of exclusive or @end multitable +@node Extended I/O specifiers +@subsection Extended I/O specifiers +@cindex @code{CARRIAGECONTROL} +@cindex @code{READONLY} +@cindex @code{SHARE} +@cindex @code{SHARED} +@cindex @code{NOSHARED} +@cindex I/O specifiers + +GNU Fortran supports the additional legacy I/O specifiers +@code{CARRIAGECONTROL}, @code{READONLY}, and @code{SHARE} with the +compile flag @option{-fdec}, for compatibility. + +@table @code +@item CARRIAGECONTROL +The @code{CARRIAGECONTROL} specifier allows a user to control line +termination settings between output records for an I/O unit. The specifier has +no meaning for readonly files. When @code{CARRAIGECONTROL} is specified upon +opening a unit for formatted writing, the exact @code{CARRIAGECONTROL} setting +determines what characters to write between output records. The syntax is: + +@smallexample +OPEN(..., CARRIAGECONTROL=cc) +@end smallexample + +Where @emph{cc} is a character expression that evaluates to one of the +following values: + +@multitable @columnfractions .2 .8 +@item @code{'LIST'} @tab One line feed between records (default) +@item @code{'FORTRAN'} @tab Legacy interpretation of the first character (see below) +@item @code{'NONE'} @tab No separator between records +@end multitable + +With @code{CARRIAGECONTROL='FORTRAN'}, when a record is written, the first +character of the input record is not written, and instead determines the output +record separator as follows: + +@multitable @columnfractions .3 .3 .4 +@headitem Leading character @tab Meaning @tab Output separating character(s) +@item @code{'+'} @tab Overprinting @tab Carriage return only +@item @code{'-'} @tab New line @tab Line feed and carriage return +@item @code{'0'} @tab Skip line @tab Two line feeds and carriage return +@item @code{'1'} @tab New page @tab Form feed and carriage return +@item @code{'$'} @tab Prompting @tab Line feed (no carriage return) +@item @code{CHAR(0)} @tab Overprinting (no advance) @tab None +@end multitable + +@item READONLY +The @code{READONLY} specifier may be given upon opening a unit, and is +equivalent to specifying @code{ACTION='READ'}, except that the file may not be +deleted on close (i.e. @code{CLOSE} with @code{STATUS="DELETE"}). The syntax +is: + +@smallexample +@code{OPEN(..., READONLY)} +@end smallexample + +@item SHARE +The @code{SHARE} specifier allows system-level locking on a unit upon opening +it for controlled access from multiple processes/threads. The @code{SHARE} +specifier has several forms: + +@smallexample +OPEN(..., SHARE=sh) +OPEN(..., SHARED) +OPEN(..., NOSHARED) +@end smallexample + +Where @emph{sh} in the first form is a character expression that evaluates to +a value as seen in the table below. The latter two forms are aliases +for particular values of @emph{sh}: + +@multitable @columnfractions .3 .3 .4 +@headitem Explicit form @tab Short form @tab Meaning +@item @code{SHARE='DENYRW'} @tab @code{NOSHARED} @tab Exclusive (write) lock +@item @code{SHARE='DENYNONE'} @tab @code{SHARED} @tab Shared (read) lock +@end multitable + +In general only one process may hold an exclusive (write) lock for a given file +at a time, whereas many processes may hold shared (read) locks for the same +file. + +The behavior of locking may vary with your operating system. On POSIX systems, +locking is implemented with @code{fcntl}. Consult your corresponding operating +system's manual pages for further details. Locking via @code{SHARE=} is not +supported on other systems. + +@end table @node Extensions not implemented in GNU Fortran @section Extensions not implemented in GNU Fortran @@ -2629,7 +2719,7 @@ code that uses them running with the GNU Fortran compiler. * Variable FORMAT expressions:: @c * Q edit descriptor:: @c * TYPE and ACCEPT I/O Statements:: -@c * CARRIAGECONTROL, DEFAULTFILE, DISPOSE and RECORDTYPE I/O specifiers:: +@c * DEFAULTFILE, DISPOSE and RECORDTYPE I/O specifiers:: @c * Omitted arguments in procedure call:: * Alternate complex function syntax:: * Volatile COMMON blocks:: |