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/*
ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010 Giovanni Di Sirio.
This file is part of ChibiOS/RT.
ChibiOS/RT 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 3 of the License, or
(at your option) any later version.
ChibiOS/RT 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, see <http://www.gnu.org/licenses/>.
*/
/**
* @file chregistry.c
* @brief Threads registry code.
*
* @addtogroup registry
* @details Threads Registry related APIs and services.
*
* <h2>Operation mode</h2>
* The Threads Registry is a double linked list that holds all the
* active threads in the system.<br>
* Operations defined for the registry:
* - <b>First</b>, returns the first, in creation order, active thread
* in the system.
* - <b>Next</b>, returns the next, in creation order, active thread
* in the system.
* .
* The registry is meant to be mainly a debug feature, as example,
* using the registry a debugger can enumerate the active threads
* in any given moment or the shell can print the active threads
* and their state.<br>
* Another possible use is for centralized threads memory management,
* terminating threads can pulse an event source and an event handler
* can perform a scansion of the registry in order to recover the
* memory.<br>
* In order to use the threads registry the @p CH_USE_REGISTRY option
* must be enabled in @p chconf.h.
* @{
*/
#include "ch.h"
#if CH_USE_REGISTRY
/**
* @brief Returns the first thread in the system.
* @details Returns the most ancient thread in the system, usually this is
* the main thread unless it terminated.
* @note A reference is added to the returned thread in order to make sure
* it status is not lost.
* @note This function cannot return @p NULL because there is always at
* least one thread in the system.
*
* @return A reference to the first thread.
*/
Thread *chRegFirstThread(void) {
Thread *tp;
chSysLock();
tp = rlist.p_newer;
#if CH_USE_DYNAMIC
tp->p_refs++;
#endif
chSysUnlock();
return tp;
}
/**
* @brief Returns the thread next to the specified one.
* @details The reference counter of the specified thread is decremented and
* the reference counter of the returned thread is incremented.
*
* @param[in] tp pointer to the thread
* @return A reference to the next thread.
* @retval NULL if there is no next thread.
*/
Thread *chRegNextThread(Thread *tp) {
Thread *ntp;
chSysLock();
ntp = tp->p_newer;
if (ntp == (Thread *)&rlist)
ntp = NULL;
#if CH_USE_DYNAMIC
else {
chDbgAssert(ntp->p_refs < 255, "chRegNextThread(), #1",
"too many references");
ntp->p_refs++;
}
#endif
chSysUnlock();
#if CH_USE_DYNAMIC
chThdRelease(tp);
#endif
return ntp;
}
#endif /* CH_USE_REGISTRY */
/** @} */
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