standards.texi

基于4个mips核的noc设计

External symbols that are not documented entry points for the user
should have names beginning with @samp{_}.  They should also contain
the chosen name prefix for the library, to prevent collisions with
other libraries.  These can go in the same files with user entry
points if you like.

Static functions and variables can be used as you like and need not
fit any naming convention.

@node Errors
@section Formatting Error Messages

Error messages from compilers should look like this:

@example
@var{source-file-name}:@var{lineno}: @var{message}
@end example

Error messages from other noninteractive programs should look like this:

@example
@var{program}:@var{source-file-name}:@var{lineno}: @var{message}
@end example

@noindent
when there is an appropriate source file, or like this:

@example
@var{program}: @var{message}
@end example

@noindent
when there is no relevant source file.

In an interactive program (one that is reading commands from a
terminal), it is better not to include the program name in an error
message.  The place to indicate which program is running is in the
prompt or with the screen layout.  (When the same program runs with
input from a source other than a terminal, it is not interactive and
would do best to print error messages using the noninteractive style.)

The string @var{message} should not begin with a capital letter when
it follows a program name and/or file name.  Also, it should not end
with a period.

Error messages from interactive programs, and other messages such as
usage messages, should start with a capital letter.  But they should not
end with a period.

@node User Interfaces
@section Standards for Command Line Interfaces

Please don't make the behavior of a utility depend on the name used
to invoke it.  It is useful sometimes to make a link to a utility
with a different name, and that should not change what it does.

Instead, use a run time option or a compilation switch or both
to select among the alternate behaviors.

Likewise, please don't make the behavior of the program depend on the
type of output device it is used with.  Device independence is an
important principle of the system's design; do not compromise it
merely to save someone from typing an option now and then.

If you think one behavior is most useful when the output is to a
terminal, and another is most useful when the output is a file or a
pipe, then it is usually best to make the default behavior the one that
is useful with output to a terminal, and have an option for the other
behavior.

Compatibility requires certain programs to depend on the type of output
device.  It would be disastrous if @code{ls} or @code{sh} did not do so
in the way all users expect.  In some of these cases, we supplement the
program with a preferred alternate version that does not depend on the
output device type.  For example, we provide a @code{dir} program much
like @code{ls} except that its default output format is always
multi-column format.

It is a good idea to follow the @sc{POSIX} guidelines for the
command-line options of a program.  The easiest way to do this is to use
@code{getopt} to parse them.  Note that the GNU version of @code{getopt}
will normally permit options anywhere among the arguments unless the
special argument @samp{--} is used.  This is not what @sc{POSIX}
specifies; it is a GNU extension.

Please define long-named options that are equivalent to the
single-letter Unix-style options.  We hope to make GNU more user
friendly this way.  This is easy to do with the GNU function
@code{getopt_long}.

One of the advantages of long-named options is that they can be
consistent from program to program.  For example, users should be able
to expect the ``verbose'' option of any GNU program which has one, to be
spelled precisely @samp{--verbose}.  To achieve this uniformity, look at
the table of common long-option names when you choose the option names
for your program (@pxref{Option Table}).

It is usually a good idea for file names given as ordinary arguments to
be input files only; any output files would be specified using options
(preferably @samp{-o} or @samp{--output}).  Even if you allow an output
file name as an ordinary argument for compatibility, try to provide an
option as another way to specify it.  This will lead to more consistency
among GNU utilities, and fewer idiosyncracies for users to remember.

All programs should support two standard options: @samp{--version}
and @samp{--help}.

@table @code
@item --version
This option should direct the program to information about its name,
version, origin and legal status, all on standard output, and then exit
successfully.  Other options and arguments should be ignored once this
is seen, and the program should not perform its normal function.

The first line is meant to be easy for a program to parse; the version
number proper starts after the last space.  In addition, it contains
the canonical name for this program, in this format:

@example
GNU Emacs 19.30
@end example

@noindent
The program's name should be a constant string; @emph{don't} compute it
from @code{argv[0]}.  The idea is to state the standard or canonical
name for the program, not its file name.  There are other ways to find
out the precise file name where a command is found in @code{PATH}.

If the program is a subsidiary part of a larger package, mention the
package name in parentheses, like this:

@example
emacsserver (GNU Emacs) 19.30
@end example

@noindent
If the package has a version number which is different from this
program's version number, you can mention the package version number
just before the close-parenthesis.

If you @strong{need} to mention the version numbers of libraries which
are distributed separately from the package which contains this program,
you can do so by printing an additional line of version info for each
library you want to mention.  Use the same format for these lines as for
the first line.

Please do not mention all of the libraries that the program uses ``just
for completeness''---that would produce a lot of unhelpful clutter.
Please mention library version numbers only if you find in practice that
they are very important to you in debugging.

The following line, after the version number line or lines, should be a
copyright notice.  If more than one copyright notice is called for, put
each on a separate line.

Next should follow a brief statement that the program is free software,
and that users are free to copy and change it on certain conditions.  If
the program is covered by the GNU GPL, say so here.  Also mention that
there is no warranty, to the extent permitted by law.

It is ok to finish the output with a list of the major authors of the
program, as a way of giving credit.

Here's an example of output that follows these rules:

@smallexample
GNU Emacs 19.34.5
Copyright (C) 1996 Free Software Foundation, Inc.
GNU Emacs comes with NO WARRANTY,
to the extent permitted by law.
You may redistribute copies of GNU Emacs
under the terms of the GNU General Public License.
For more information about these matters,
see the files named COPYING.
@end smallexample

You should adapt this to your program, of course, filling in the proper
year, copyright holder, name of program, and the references to
distribution terms, and changing the rest of the wording as necessary.

This copyright notice only needs to mention the most recent year in
which changes were made---there's no need to list the years for previous
versions' changes.  You don't have to mention the name of the program in
these notices, if that is inconvenient, since it appeared in the first
line.

@item --help
This option should output brief documentation for how to invoke the
program, on standard output, then exit successfully.  Other options and
arguments should be ignored once this is seen, and the program should
not perform its normal function.

Near the end of the @samp{--help} option's output there should be a line
that says where to mail bug reports.  It should have this format:

@example
Report bugs to @var{mailing-address}.
@end example
@end table

@node Option Table
@section Table of Long Options

Here is a table of long options used by GNU programs.  It is surely
incomplete, but we aim to list all the options that a new program might
want to be compatible with.  If you use names not already in the table,
please send @email{gnu@@gnu.org} a list of them, with their
meanings, so we can update the table.

@c Please leave newlines between items in this table; it's much easier
@c to update when it isn't completely squashed together and unreadable.
@c When there is more than one short option for a long option name, put
@c a semicolon between the lists of the programs that use them, not a
@c period.   --friedman

@table @samp
@item after-date
@samp{-N} in @code{tar}.

@item all
@samp{-a} in @code{du}, @code{ls}, @code{nm}, @code{stty}, @code{uname},
and @code{unexpand}.

@item all-text
@samp{-a} in @code{diff}.

@item almost-all
@samp{-A} in @code{ls}.

@item append
@samp{-a} in @code{etags}, @code{tee}, @code{time};
@samp{-r} in @code{tar}.

@item archive
@samp{-a} in @code{cp}.

@item archive-name
@samp{-n} in @code{shar}.

@item arglength
@samp{-l} in @code{m4}.

@item ascii
@samp{-a} in @code{diff}.

@item assign
@samp{-v} in @code{gawk}.

@item assume-new
@samp{-W} in Make.

@item assume-old
@samp{-o} in Make.

@item auto-check
@samp{-a} in @code{recode}.

@item auto-pager
@samp{-a} in @code{wdiff}.

@item auto-reference
@samp{-A} in @code{ptx}.

@item avoid-wraps
@samp{-n} in @code{wdiff}.

@item backward-search
@samp{-B} in @code{ctags}.

@item basename
@samp{-f} in @code{shar}.

@item batch
Used in GDB.

@item baud
Used in GDB.

@item before
@samp{-b} in @code{tac}.

@item binary
@samp{-b} in @code{cpio} and @code{diff}.

@item bits-per-code
@samp{-b} in @code{shar}.

@item block-size
Used in @code{cpio} and @code{tar}.

@item blocks
@samp{-b} in @code{head} and @code{tail}.

@item break-file
@samp{-b} in @code{ptx}.

@item brief
Used in various programs to make output shorter.

@item bytes
@samp{-c} in @code{head}, @code{split}, and @code{tail}.

@item c@t{++}
@samp{-C} in @code{etags}.

@item catenate
@samp{-A} in @code{tar}.

@item cd
Used in various programs to specify the directory to use.

@item changes
@samp{-c} in @code{chgrp} and @code{chown}.

@item classify
@samp{-F} in @code{ls}.

@item colons
@samp{-c} in @code{recode}.

@item command
@samp{-c} in @code{su};
@samp{-x} in GDB.

@item compare
@samp{-d} in @code{tar}.

@item compat
Used in @code{gawk}.

@item compress
@samp{-Z} in @code{tar} and @code{shar}.

@item concatenate
@samp{-A} in @code{tar}.

@item confirmation
@samp{-w} in @code{tar}.

@item context
Used in @code{diff}.

@item copyleft
@samp{-W copyleft} in @code{gawk}.

@item copyright
@samp{-C} in @code{ptx}, @code{recode}, and @code{wdiff};
@samp{-W copyright} in @code{gawk}.

@item core
Used in GDB.

@item count
@samp{-q} in @code{who}.

@item count-links
@samp{-l} in @code{du}.

@item create
Used in @code{tar} and @code{cpio}.

@item cut-mark
@samp{-c} in @code{shar}.

@item cxref
@samp{-x} in @code{ctags}.

@item date
@samp{-d} in @code{touch}.

@item debug
@samp{-d} in Make and @code{m4};
@samp{-t} in Bison.

@item define
@samp{-D} in @code{m4}.

@item defines
@samp{-d} in Bison and @code{ctags}.

@item delete
@samp{-D} in @code{tar}.

@item dereference
@samp{-L} in @code{chgrp}, @code{chown}, @code{cpio}, @code{du},
@code{ls}, and @code{tar}.

@item dereference-args
@samp{-D} in @code{du}.

@item diacritics
@samp{-d} in @code{recode}.

@item dictionary-order
@samp{-d} in @code{look}.

@item diff
@samp{-d} in @code{tar}.

@item digits
@samp{-n} in @code{csplit}.

@item directory
Specify the directory to use, in various programs.  In @code{ls}, it
means to show directories themselves rather than their contents.  In
@code{rm} and @code{ln}, it means to not treat links to directories
specially.

@item discard-all
@samp{-x} in @code{strip}.

@item discard-locals
@samp{-X} in @code{strip}.

@item dry-run
@samp{-n} in Make.

@item ed
@samp{-e} in @code{diff}.

@item elide-empty-files
@samp{-z} in @code{csplit}.

@item end-delete
@samp{-x} in @code{wdiff}.

@item end-insert
@samp{-z} in @code{wdiff}.

@item entire-new-file
@samp{-N} in @code{diff}.

@item environment-overrides
@samp{-e} in Make.

@item eof
@samp{-e} in @code{xargs}.

@item epoch
Used in GDB.

@item error-limit
Used in @code{makeinfo}.

@item error-output
@samp{-o} in @code{m4}.

@item escape
@samp{-b} in @code{ls}.

@item exclude-from
@samp{-X} in @code{tar}.

@item exec
Used in GDB.

@item exit
@samp{-x} in @code{xargs}.

@item exit-0
@samp{-e} in @code{unshar}.

@item expand-tabs
@samp{-t} in @code{diff}.

@item expression
@samp{-e} in @code{sed}.

@item extern-only
@samp{-g} in @code{nm}.

@item extract
@samp{-i} in @code{cpio};
@samp{-x} in @code{tar}.