defs.h

hid 应用代码 支持输入输出端口扩展,模拟量采集.

#ifndef foodefshfoo
#define foodefshfoo

/* $Id: defs.h 1511 2007-08-12 15:41:45Z lennart $ */

/***
  This file is part of avahi.
 
  avahi is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as
  published by the Free Software Foundation; either version 2.1 of the
  License, or (at your option) any later version.
 
  avahi is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
  Public License for more details.
 
  You should have received a copy of the GNU Lesser General Public
  License along with avahi; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  USA.
***/

/** \file defs.h Some common definitions */

#include <avahi-common/cdecl.h>

/** \mainpage
 *  
 * \section choose_api Choosing an API
 *
 * Avahi provides three programming APIs for integration of
 * mDNS/DNS-SD features into your C progams:
 *
 * \li <b>avahi-core</b>: an API for embedding a complete mDNS/DNS-SD stack
 * into your software. This is intended for developers of embedded
 * ampliances only. We dissuade from using this API in normal desktop
 * applications since it is not a good idea to run multiple mDNS
 * stacks simultaneously on the same host.
 * \li <b>the D-Bus API</b>: an extensive D-Bus interface for browsing and
 * registering mDNS/DNS-SD services using avahi-daemon. We recommend
 * to use this API for software written in any language but
 * C. (i.e. Python)
 * \li <b>avahi-client</b>: a simplifying C wrapper around the D-Bus API. We
 * recommend to use this API in C or C++ progams. The D-Bus internals
 * are hidden completely.
 * 
 * All three APIs are very similar, however avahi-core is the most powerful.
 *
 * In addition to the three APIs described above Avahi supports two
 * compatibility libraries:
 *
 * \li <b>avahi-compat-libdns_sd</b>: the original Bonjour API as documented
 * in the header file "dns_sd.h" by Apple Computer, Inc.
 *
 * \li <b>avahi-compat-howl</b>: the HOWL API as released with HOWL 0.9.8 by
 * Porchdog Software.
 *
 * Please note that these compatibility layers are incomplete and
 * generally a waste of resources. We strongly encourage everyone to
 * use our native APIs for newly written programs and to port older
 * programs to avahi-client!
 *
 * The native APIs (avahi-client and avahi-core) can be integrated
 * into external event loops. We provide adapters for the following
 * event loop implementations:
 *
 * \li <b>avahi-glib</b>: The GLIB main loop as used by GTk+/GNOME
 *
 * \li <b>avahi-qt</b>: The Qt main loop as used by Qt/KDE
 *
 * Finally, we provide a high-level Gtk+ GUI dialog called
 * <b>avahi-ui</b> for user-friendly browsing for services.
 *
 * The doxygen-generated API documentation covers avahi-client
 * (including its auxiliary APIs), the event loop adapters and
 * avahi-ui. For the other APIs please consult the original
 * documentation (for the compatibility APIs) or the header files.
 *
 * Please note that the doxygen-generated API documentation of the
 * native Avahi API is not complete. A few definitions that are part
 * of the Avahi API have been removed from this documentation, either
 * because they are only relevant in a very few low-level applications
 * or because they are considered obsolete. Please consult the C header
 * files for all definitions that are part of the Avahi API. Please
 * note that these hidden definitions are considered part of the Avahi
 * API and will stay available in the API in the future.
 * 
 * \section error_reporting Error Reporting
 *
 * Some notes on the Avahi error handling:
 *
 * - Error codes are negative integers and defined as AVAHI_ERR_xx
 * - If a function returns some kind of non-negative integer value on
 * success, a failure is indicated by returning the error code
 * directly.
 * - If a function returns a pointer of some kind on success, a
 * failure is indicated by returning NULL
 * - The last error number may be retrieved by calling
 * avahi_client_errno()
 * - Just like the libc errno variable the Avahi errno is NOT reset to
 * AVAHI_OK if a function call succeeds.
 * - You may convert a numeric error code into a human readable string
 * using avahi_strerror()
 * - The constructor function avahi_client_new() returns the error
 * code in a call-by-reference argument
 *
 * \section event_loop Event Loop Abstraction
 *
 * Avahi uses a simple event loop abstraction laye. A table AvahiPoll
 * which contains function pointers for user defined timeout and I/O
 * condition event source implementations needs to be passed to
 * avahi_client_new(). An adapter for this abstraction layer is
 * available for the GLib main loop in the object AvahiGLibPoll. A
 * simple stand-alone implementation is available under the name
 * AvahiSimplePoll. An adpater for the Qt main loop is available from
 * avahi_qt_poll_get().
 *
 * \section good_publish How to Register Services
 *
 * - Subscribe to server state changes. Pass a callback function
 * pointer to avahi_client_new(). It will be called
 * whenever the server state changes.
 * - Only register your services when the server is in state
 * AVAHI_SERVER_RUNNING. If you register your services in other server
 * states they might not be accessible since the local host name might not necessarily
 * be established.
 * - Remove your services when the server enters
 * AVAHI_SERVER_COLLISION or AVAHI_SERVER_REGISTERING state. Your
 * services may no be reachable anymore since the local host name is
 * no longer established or is currently in the process of being
 * established.
 * - When registering services, use the following algorithm:
 *   - Create a new entry group (i.e. avahi_entry_group_new())
 *   - Add your service(s)/additional RRs/subtypes (e.g. avahi_entry_group_add_service())
 *   - Commit the entry group (i.e. avahi_entry_group_commit())
 * - Subscribe to entry group state changes.
 * - If the entry group enters AVAHI_ENTRY_GROUP_COLLISION state the
 * services of the entry group are automatically removed from the
 * server. You may immediately add your services back to the entry
 * group (but with new names, perhaps using
 * avahi_alternative_service_name()) and commit again. Please do not
 * free the entry group and create a new one. This would inhibit some
 * traffic limiting algorithms in mDNS.
 * - When you need to modify your services (i.e. change the TXT data
 * or the port number), use the AVAHI_PUBLISH_UPDATE flag. Please do
 * not free the entry group and create a new one. This would inhibit
 * some traffic limiting algorithms in mDNS. When changing just the
 * TXT data avahi_entry_group_update_txt() is a shortcut for
 * AVAHI_PUBLISH_UPDATE. Please note that you cannot use
 * AVAHI_PUBLISH_UPDATE when changing the service name! Renaming a
 * DNS-SD service is identical to deleting and creating a new one, and
 * that's exactly what you should do in that case. First call
 * avahi_entry_group_reset() to remove it and than readd it normally.
 *
 * \section good_browse How to Browse for Services
 *
 * - For normal applications you need to call avahi_service_browser_new()
 * for the service type you want to browse for. Use
 * avahi_service_resolver_new() to acquire service data for a service
 * name.
 * - You can use avahi_domain_browser_new() to get a list of announced
 * browsing domains. Please note that not all domains whith services
 * on the LAN are mandatorily announced.
 * - There is no need to subscribe to server state changes.
 *
 * \section daemon_dies How to Write a Client That Can Deal with Daemon Restarts
 *
 * With Avahi it is possible to write client applications that can
 * deal with Avahi daemon restarts. To accomplish that make sure to
 * pass AVAHI_CLIENT_NO_FAIL to avahi_client_new()'s flags
 * parameter. That way avahi_client_new() will succeed even when the
 * daemon is not running. In that case the object will enter
 * AVAHI_CLIENT_CONNECTING state. As soon as the daemon becomes
 * available the object will enter one of the AVAHI_CLIENT_S_xxx
 * states. Make sure to not create browsers or entry groups before the
 * client object has entered one of those states. As usual you will be