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//$Id: TransformAlarmC.nc,v 1.6 2010-06-29 22:07:50 scipio Exp $
/* Copyright (c) 2000-2003 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - 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.
* - Neither the name of the copyright holder 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 COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.
*/
/**
* TransformAlarmC decreases precision and/or widens an Alarm. An already
* widened Counter component is used to help.
*
* <p>See TEP102 for more details.
* @param to_precision_tag A type indicating the precision of the transformed
* Alarm.
* @param to_size_type The type for the width of the transformed Alarm.
* @param from_precision_tag A type indicating the precision of the original
* Alarm.
* @param from_size_type The type for the width of the original Alarm.
* @param bit_shift_right Original time units will be 2 to the power
* <code>bit_shift_right</code> larger than transformed time units.
*
* @author Cory Sharp <cssharp@eecs.berkeley.edu>
*/
generic module TransformAlarmC(
typedef to_precision_tag,
typedef to_size_type @integer(),
typedef from_precision_tag,
typedef from_size_type @integer(),
uint8_t bit_shift_right) @safe()
{
/**
* The transformed Alarm.
*/
provides interface Alarm<to_precision_tag,to_size_type>;
/**
* Users of this component must wire Counter to an already-widened
* Counter (with the same precision as the new Alarm). See
* TransformCounterC for one possible implementation.
*/
uses interface Counter<to_precision_tag,to_size_type>;
/**
* The original Alarm.
*/
uses interface Alarm<from_precision_tag,from_size_type> as AlarmFrom;
}
implementation
{
to_size_type m_t0;
to_size_type m_dt;
enum
{
MAX_DELAY_LOG2 = 8 * sizeof(from_size_type) - 1 - bit_shift_right,
MAX_DELAY = ((to_size_type)1) << MAX_DELAY_LOG2,
};
async command to_size_type Alarm.getNow()
{
return call Counter.get();
}
async command to_size_type Alarm.getAlarm()
{
atomic return m_t0 + m_dt;
//return m_t0 + m_dt;
}
async command bool Alarm.isRunning()
{
return call AlarmFrom.isRunning();
}
async command void Alarm.stop()
{
call AlarmFrom.stop();
}
void set_alarm()
{
to_size_type now = call Counter.get(), expires, remaining;
/* m_t0 is assumed to be in the past. If it's > now, we assume
that time has wrapped around */
expires = m_t0 + m_dt;
/* The cast is necessary to get correct wrap-around arithmetic */
remaining = (to_size_type)(expires - now);
/* if (expires <= now) remaining = 0; in wrap-around arithmetic */
if (m_t0 <= now)
{
if (expires >= m_t0 && // if it wraps, it's > now
expires <= now)
remaining = 0;
}
else
{
if (expires >= m_t0 || // didn't wrap so < now
expires <= now)
remaining = 0;
}
if (remaining > MAX_DELAY)
{
m_t0 = now + MAX_DELAY;
m_dt = remaining - MAX_DELAY;
remaining = MAX_DELAY;
}
else
{
m_t0 += m_dt;
m_dt = 0;
}
call AlarmFrom.startAt((from_size_type)now << bit_shift_right,
(from_size_type)remaining << bit_shift_right);
}
async command void Alarm.startAt(to_size_type t0, to_size_type dt)
{
atomic
{
m_t0 = t0;
m_dt = dt;
set_alarm();
}
}
async command void Alarm.start(to_size_type dt)
{
call Alarm.startAt(call Alarm.getNow(), dt);
}
async event void AlarmFrom.fired()
{
atomic
{
if(m_dt == 0)
{
signal Alarm.fired();
}
else
{
set_alarm();
}
}
}
async event void Counter.overflow()
{
}
default async event void Alarm.fired()
{
}
}
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