contiki/core/sys/service.h

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/*
* Copyright (c) 2005, Swedish Institute of Computer Science
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* This file is part of the Contiki operating system.
*
* @(#)$Id: service.h,v 1.2 2006/09/09 23:25:07 oliverschmidt Exp $
*/
/** \addtogroup sys
* @{
*/
/**
* \defgroup service The Contiki service mechanism
*
* The Contiki service mechanism enables cross-process functions. A
* service that is registered by one process can be accessed by other
* processes in the system. Services can be transparently replaced at
* run-time.
*
* A service has an interface that callers use to access the service's
* functions. This interface typically is defined in a header file
* that is included by all users of the service. A service interface
* is defined with the SERVICE_INTERFACE() macro.
*
* A service implementation is declared with the SERVICE() macro. The
* SERVICE() statement specifies the actual functions that are used to
* implement the service.
*
* Every service has a controlling process. The controlling process
* registers the service with the system when it starts, and is also
* notified if the service is removed or replaced. A process may
* register any number of services.
*
* Service registration is done with a SERVICE_REGISTER()
* statement. If a service with the same name is already registered,
* this is removed before the new service is registered.
*
* The SERVICE_CALL() macro is used to call a service. If the service
* to be called is not registered, the SERVICE_CALL() statement does
* nothing. The SERVICE_FIND() function can be used to check if a
* particular service exists before calling SERVICE_CALL().
*
* @{
*/
/**
* \file
* Header file for the Contiki service mechanism.
* \author
* Adam Dunkels <adam@sics.se>
*/
#ifndef __SERVICE_H__
#define __SERVICE_H__
#include "contiki.h"
struct service {
struct service *next;
struct process *p;
const char *name;
const void *interface;
};
/**
* \name Service declaration and defition
* @{
*/
/**
* Define the name and interface of a service.
*
* This statement defines the name and interface of a service.
*
* \param name The name of the service.
*
* \param interface A list of function declarations that comprises the
* service interface. This list must be enclosed by curly brackets and
* consist of declarations of function pointers separated by
* semicolons.
*
* \hideinitializer
*/
#define SERVICE_INTERFACE(name, interface) struct name interface;
#if ! CC_NO_VA_ARGS
/**
* \brief Define an implementation of a service interface.
* \param name The name of this particular instance of the service, for use with SERVICE_REGISTER().
* \param service_name The name of the service, from the SERVICE_INTERFACE().
* \param ... A structure containing the functions that implements the service.
*
* This statement defines the name of this implementation
* of the service and defines the functions that actually
* implement the functions offered by the service.
*
* \hideinitializer
*/
#define SERVICE(name, service_name, ...) \
static struct service_name name##_interface = __VA_ARGS__ ; \
struct service name = { NULL, NULL, service_name##_name, & name##_interface }
#endif
/** @} */
/**
* \name Calling a service
* @{
*/
/**
* Call a function from a specified service, if it is registered.
*
*
* \param service_name The name of the service that is to be called.
*
* \param function The function that is to be called. This is a full
* function call, including parameters.
*
* \hideinitializer
*/
#define SERVICE_CALL(service_name, function) \
{ \
struct service *service_s; \
service_s = service_find(service_name##_name); \
if(service_s != NULL) { \
((const struct service_name *)service_s->interface)->function; \
} \
}
/* @} */
#define SERVICE_EXISTS(service_name) (service_find(service_name##_name) != NULL)
/**
* \name Service registration and removal
* @{
*/
/**
* Register a service.
*
* \hideinitializer
*/
#define SERVICE_REGISTER(name) service_register(&name)
/**
* Remove a service.
*
* \hideinitializer
*/
#define SERVICE_REMOVE(service_name) service_remove(&service_name)
/** @} */
/**
* Find service.
*
* \hideinitializer
*/
#define SERVICE_FIND(service_name) service_find(service_name##_name)
CCIF void service_register(struct service *s);
CCIF void service_remove(struct service *s);
struct service *service_find(const char *name);
#endif /* __SERVICE_H__ */
/** @} */
/** @} */