OpenModem/bertos/mware/resource.h
2014-04-03 22:21:37 +02:00

106 lines
3.3 KiB
C

/**
* \file
* <!--
* This file is part of BeRTOS.
*
* Bertos is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* As a special exception, you may use this file as part of a free software
* library without restriction. Specifically, if other files instantiate
* templates or use macros or inline functions from this file, or you compile
* this file and link it with other files to produce an executable, this
* file does not by itself cause the resulting executable to be covered by
* the GNU General Public License. This exception does not however
* invalidate any other reasons why the executable file might be covered by
* the GNU General Public License.
*
* Copyright 2006 Develer S.r.l. (http://www.develer.com/)
* All Rights Reserved.
* -->
*
* \brief TODO:
*
*
* \author Bernie Innocenti <bernie@codewiz.org>
* \author Stefano Fedrigo <aleph@develer.com>
*/
#ifndef MWARE_RESOURCE_H
#define MWARE_RESOURCE_H
#include <drv/timer.h> // time_t
#include <kern/sem.h>
#warning FIXME:Revise me!
/*
* Abstract locking primitives used by host OS.
*/
typedef Semaphore ResourceLock;
#define ResMan_sleep() timer_delay(1)
#define ResMan_time_t mtime_t
// Forward decl
struct Observer;
/**
* Hold context information for a resource such as an audio channel.
*
* Each driver registers one or more Resource instances with the
* ResMan using ResMan_Register().
*
* Clients can then allocate the resource through ResMan_Alloc()
* providing a desired priority and an Observer for asynchronous
* notification.
*
* Allocated resources can be stolen by other clients asking for a
* higher priority. ResMan notifies a preemption request by invoking
* the Observer of the current owner.
*
* The Observer callback must take whatever action is needed to
* release the resource as soon as possible to avoid blocking the
* new owner.
*/
typedef struct Resource
{
//Private
/// Control access to fields below.
Semaphore lock;
/// Pointer to current owner's observer. NULL if resource is free.
struct Observer *owner;
/// Priority of current owner (higher values mean higher priority).
int pri;
/// Queue of processes waiting to obtain the resource.
List queue;
} Resource;
/// Event sent by ResMan to owners when to request resource release.
enum { EVENT_RELEASE = 1 };
/// Try to allocate a resource \a res with priority \a pri for at most \a timeout ticks.
bool ResMan_Alloc(Resource *res, int pri, ResMan_time_t timeout, struct Observer *releaseRequest);
/// Free resource \a res. Will eventually wake-up other queued owners.
void ResMan_Free(Resource *res);
void ResMan_Init(Resource *res);
#endif /* MWARE_RESOURCE_H */