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/*
ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
2011,2012,2013 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 chschd.h
* @brief Scheduler macros and structures.
*
* @addtogroup scheduler
* @{
*/
#ifndef _CHSCHD_H_
#define _CHSCHD_H_
/*===========================================================================*/
/* Module constants. */
/*===========================================================================*/
/**
* @name Wakeup status codes
* @{
*/
#define RDY_OK 0 /**< @brief Normal wakeup message. */
#define RDY_TIMEOUT -1 /**< @brief Wakeup caused by a timeout
condition. */
#define RDY_RESET -2 /**< @brief Wakeup caused by a reset
condition. */
/** @} */
/**
* @name Priority constants
* @{
*/
#define NOPRIO 0 /**< @brief Ready list header priority. */
#define IDLEPRIO 1 /**< @brief Idle thread priority. */
#define LOWPRIO 2 /**< @brief Lowest user priority. */
#define NORMALPRIO 64 /**< @brief Normal user priority. */
#define HIGHPRIO 127 /**< @brief Highest user priority. */
#define ABSPRIO 255 /**< @brief Greatest possible priority. */
/** @} */
/**
* @name Special time constants
* @{
*/
/**
* @brief Zero time specification for some functions with a timeout
* specification.
* @note Not all functions accept @p TIME_IMMEDIATE as timeout parameter,
* see the specific function documentation.
*/
#define TIME_IMMEDIATE ((systime_t)0)
/**
* @brief Infinite time specification for all functions with a timeout
* specification.
*/
#define TIME_INFINITE ((systime_t)-1)
/** @} */
/*===========================================================================*/
/* Module pre-compile time settings. */
/*===========================================================================*/
/*===========================================================================*/
/* Derived constants and error checks. */
/*===========================================================================*/
/*===========================================================================*/
/* Module data structures and types. */
/*===========================================================================*/
/*===========================================================================*/
/* Module macros. */
/*===========================================================================*/
/**
* @brief Returns the priority of the first thread on the given ready list.
*
* @notapi
*/
#define firstprio(rlp) ((rlp)->p_next->p_prio)
/**
* @brief Current thread pointer access macro.
* @note This macro is not meant to be used in the application code but
* only from within the kernel, use the @p chThdSelf() API instead.
* @note It is forbidden to use this macro in order to change the pointer
* (currp = something), use @p setcurrp() instead.
*/
#define currp ch.rlist.r_current
/**
* @brief Current thread pointer change macro.
* @note This macro is not meant to be used in the application code but
* only from within the kernel.
*
* @notapi
*/
#define setcurrp(tp) (currp = (tp))
/*===========================================================================*/
/* External declarations. */
/*===========================================================================*/
/*
* Scheduler APIs.
*/
#ifdef __cplusplus
extern "C" {
#endif
void _scheduler_init(void);
thread_t *chSchReadyI(thread_t *tp);
void chSchGoSleepS(tstate_t newstate);
msg_t chSchGoSleepTimeoutS(tstate_t newstate, systime_t time);
void chSchWakeupS(thread_t *tp, msg_t msg);
void chSchRescheduleS(void);
bool chSchIsPreemptionRequired(void);
void chSchDoRescheduleBehind(void);
void chSchDoRescheduleAhead(void);
void chSchDoReschedule(void);
#ifdef __cplusplus
}
#endif
/*===========================================================================*/
/* Module inline functions. */
/*===========================================================================*/
/**
* @brief Determines if the current thread must reschedule.
* @details This function returns @p true if there is a ready thread with
* higher priority.
*
* @iclass
*/
static inline bool chSchIsRescRequiredI(void) {
chDbgCheckClassI();
return firstprio(&ch.rlist.r_queue) > currp->p_prio;
}
/**
* @brief Determines if yielding is possible.
* @details This function returns @p true if there is a ready thread with
* equal or higher priority.
*
* @sclass
*/
static inline bool chSchCanYieldS(void) {
chDbgCheckClassI();
return firstprio(&ch.rlist.r_queue) >= currp->p_prio;
}
/**
* @brief Yields the time slot.
* @details Yields the CPU control to the next thread in the ready list with
* equal or higher priority, if any.
*
* @sclass
*/
static inline void chSchDoYieldS(void) {
chDbgCheckClassS();
if (chSchCanYieldS())
chSchDoRescheduleBehind();
}
/**
* @brief Inline-able preemption code.
* @details This is the common preemption code, this function must be invoked
* exclusively from the port layer.
*
* @special
*/
static inline void chSchPreemption(void) {
tprio_t p1 = firstprio(&ch.rlist.r_queue);
tprio_t p2 = currp->p_prio;
#if CH_CFG_TIME_QUANTUM > 0
if (currp->p_preempt) {
if (p1 > p2)
chSchDoRescheduleAhead();
}
else {
if (p1 >= p2)
chSchDoRescheduleBehind();
}
#else /* CH_CFG_TIME_QUANTUM == 0 */
if (p1 >= p2)
chSchDoRescheduleAhead();
#endif /* CH_CFG_TIME_QUANTUM == 0 */
}
#endif /* _CHSCHD_H_ */
/** @} */
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