mirror of https://github.com/rusefi/ChibiOS.git
Experimental preemptive round robin module. To be tested.
git-svn-id: svn://svn.code.sf.net/p/chibios/svn/trunk@11074 35acf78f-673a-0410-8e92-d51de3d6d3f4
This commit is contained in:
Giovanni Di Sirio
parent
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/*
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ChibiOS - Copyright (C) 2006..2016 Giovanni Di Sirio.
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This file is part of ChibiOS.
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ChibiOS is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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ChibiOS is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file chpreempt.h
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* @brief Preemption enforcement structures and macros.
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*
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* @addtogroup preemption_enforcement
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* @{
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*/
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#ifndef CHPREEMPT_H
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#define CHPREEMPT_H
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/* This header is included from chconf.h and that can be included by asm
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modules.*/
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#if !defined(_FROM_ASM_)
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/*===========================================================================*/
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/* Module constants. */
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/*===========================================================================*/
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/**
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* @brief Hooks function @p chSchIsPreemptionRequired().
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*/
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#define CH_SCH_IS_PREEMPTION_REQUIRED_HOOKED
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/**
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* @brief Hooks function @p chSchDoReschedule().
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*/
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#define CH_SCH_DO_RESCHEDULE_HOOKED
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/*===========================================================================*/
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/* Module pre-compile time settings. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Derived constants and error checks. */
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/*===========================================================================*/
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#if !defined(CH_CFG_ROUND_ROBIN_QUANTUM)
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#error "CH_CFG_ROUND_ROBIN_QUANTUM not defined in chconf.h"
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#endif
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#if CH_CFG_ROUND_ROBIN_QUANTUM <= 0
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#error "CH_CFG_ROUND_ROBIN_QUANTUM must be greater than zero"
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#endif
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#if CH_CFG_TIME_QUANTUM > 0
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#error "CH_CFG_ROUND_ROBIN_QUANTUM is not compatible with CH_CFG_TIME_QUANTUM > 0"
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#endif
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/*===========================================================================*/
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/* Module data structures and types. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Module macros. */
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/*===========================================================================*/
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/**
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* @brief Fields to be added to the @p ch_system_t structure.
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*
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* @notapi
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*/
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#define CH_PREEMPT_SYSTEM_FIELDS \
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virtual_timer_t preempt_vt;
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/*===========================================================================*/
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/* External declarations. */
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/*===========================================================================*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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void ch_preempt_system_init(void);
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void ch_preempt_thread_switch(void);
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#ifdef __cplusplus
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}
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#endif
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/*===========================================================================*/
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/* Module inline functions. */
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/*===========================================================================*/
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#endif /* !defined(_FROM_ASM_) */
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#endif /* CHPREEMPT_H */
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/** @} */
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@ -0,0 +1,153 @@
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/*
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ChibiOS - Copyright (C) 2006..2016 Giovanni Di Sirio.
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This file is part of ChibiOS.
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ChibiOS is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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ChibiOS is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file chpreempt.c
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* @brief Preemption enforcement code.
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*
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* @addtogroup preemption_enforcement
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* @details This modules export hook macros required for implementing
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* a preemptive round robin mode for threads at the same priority
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* level.<br>
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* This method is alternative to the ChibiOS/RT native implementation
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* which is not compatible with the tick-less mode, however, this
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* timers-based solution can decrease threads context-switch
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* performance because the added overhead.
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* @note This file is not included automatically by @p ch.h, you need
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* to:
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* - Define @p CH_CFG_ROUND_ROBIN_QUANTUM in chconf.h. It is the
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* time quantum in ticks.
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* - Include @p chpreempt.h from @p chconf.h.
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* - Add all the macros and functions to the appropriate hooks in
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* chconf.h.
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* - Explicitely add @p chpreempt.c to your makefile.
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* .
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*/
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#include "ch.h"
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/*===========================================================================*/
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/* Module exported variables. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Module local types. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Module local variables. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Module local functions. */
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/*===========================================================================*/
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static void preempt_cb(void *p) {
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(void)p;
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}
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/*===========================================================================*/
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/* Module exported functions. */
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/*===========================================================================*/
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/**
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* @brief Hook code for system initialization.
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*
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* @notapi
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*/
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void ch_preempt_system_init(void) {
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chVTObjectInit(&ch.preempt_vt);
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}
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/**
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* @brief Hook code for context switch.
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*
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* @notapi
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*/
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void ch_preempt_thread_switch(void) {
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chVTSetI(&ch.preempt_vt, CH_CFG_ROUND_ROBIN_QUANTUM, preempt_cb, NULL);
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}
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/**
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* @brief Evaluates if preemption is required.
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* @details The decision is taken by comparing the relative priorities and
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* depending on the state of the round robin timeout counter.
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* @note Not a user function, it is meant to be invoked by the scheduler
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* itself or from within the port layer.
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*
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* @retval true if there is a thread that must go in running state
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* immediately.
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* @retval false if preemption is not required.
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*
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* @special
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*/
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bool chSchIsPreemptionRequired(void) {
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tprio_t p1 = firstprio(&ch.rlist.queue);
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tprio_t p2 = currp->prio;
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/* If the running thread has not reached its time quantum, reschedule only
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if the first thread on the ready queue has a higher priority.
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Otherwise, if the running thread has used up its time quantum, reschedule
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if the first thread on the ready queue has equal or higher priority.*/
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return chVTIsArmed(&ch.preempt_vt) ? (p1 > p2) : (p1 >= p2);
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}
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/**
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* @brief Switches to the first thread on the runnable queue.
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* @details The current thread is positioned in the ready list behind or
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* ahead of all threads having the same priority depending on
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* if it used its whole time slice.
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* @note Not a user function, it is meant to be invoked by the scheduler
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* itself or from within the port layer.
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*
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* @special
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*/
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void chSchDoReschedule(void) {
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thread_t *otp = currp;
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/* Picks the first thread from the ready queue and makes it current.*/
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currp = queue_fifo_remove(&ch.rlist.queue);
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currp->state = CH_STATE_CURRENT;
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/* Handling idle-leave hook.*/
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if (otp->prio == IDLEPRIO) {
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CH_CFG_IDLE_LEAVE_HOOK();
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}
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/* There are two different scenarios to handle on preemption: time quantum
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elapsed or not.*/
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if (!chVTIsArmed(&ch.preempt_vt)) {
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/* The thread consumed its time quantum so it is enqueued behind threads
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with same priority level, however, it acquires a new time quantum.*/
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otp = chSchReadyI(otp);
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}
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else {
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/* The thread didn't consume all its time quantum so it is put ahead of
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threads with equal priority and does not acquire a new time quantum.*/
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otp = chSchReadyAheadI(otp);
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}
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/* Swap operation as tail call.*/
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chSysSwitch(currp, otp);
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}
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/** @} */
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@ -462,6 +462,7 @@ void chSchRescheduleS(void) {
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}
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}
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#if !defined(CH_SCH_IS_PREEMPTION_REQUIRED_HOOKED)
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/**
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* @brief Evaluates if preemption is required.
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* @details The decision is taken by comparing the relative priorities and
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@ -491,6 +492,7 @@ bool chSchIsPreemptionRequired(void) {
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return p1 > p2;
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#endif
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}
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#endif /* !defined(CH_SCH_IS_PREEMPTION_REQUIRED_HOOKED) */
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/**
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* @brief Switches to the first thread on the runnable queue.
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@ -554,6 +556,7 @@ void chSchDoRescheduleAhead(void) {
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chSysSwitch(currp, otp);
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}
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#if !defined(CH_SCH_DO_RESCHEDULE_HOOKED)
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/**
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* @brief Switches to the first thread on the runnable queue.
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* @details The current thread is positioned in the ready list behind or
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@ -602,5 +605,6 @@ void chSchDoReschedule(void) {
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/* Swap operation as tail call.*/
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chSysSwitch(currp, otp);
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}
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#endif /*!defined(CH_SCH_DO_RESCHEDULE_HOOKED) */
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/** @} */
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