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/*
* Copyright (C) 2014 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup core_sched
* @{
*
* @file sched.c
* @brief Scheduler implementation
*
* @author Kaspar Schleiser <kaspar@schleiser.de>
*
* @}
*/
#include <stdint.h>
#include "sched.h"
#include "kernel.h"
#include "kernel_internal.h"
#include "clist.h"
#include "bitarithm.h"
#include "irq.h"
#include "thread.h"
#include "irq.h"
#if SCHEDSTATISTICS
#include "hwtimer.h"
#endif
#define ENABLE_DEBUG (0)
#include "debug.h"
volatile int sched_num_threads = 0;
volatile unsigned int sched_context_switch_request;
volatile tcb_t *sched_threads[MAXTHREADS];
volatile tcb_t *sched_active_thread;
volatile int sched_active_pid = -1;
clist_node_t *sched_runqueues[SCHED_PRIO_LEVELS];
static uint32_t runqueue_bitcache = 0;
#if SCHEDSTATISTICS
static void (*sched_cb) (uint32_t timestamp, uint32_t value) = NULL;
schedstat sched_pidlist[MAXTHREADS];
#endif
void sched_run(void)
{
sched_context_switch_request = 0;
#ifdef SCHEDSTATISTICS
unsigned long time = hwtimer_now();
#endif
tcb_t *my_active_thread = (tcb_t *)sched_active_thread;
if (my_active_thread) {
if (my_active_thread->status == STATUS_RUNNING) {
my_active_thread->status = STATUS_PENDING;
}
#ifdef SCHED_TEST_STACK
if (*((unsigned int *)my_active_thread->stack_start) != (unsigned int) my_active_thread->stack_start) {
printf("scheduler(): stack overflow detected, task=%s pid=%u\n", my_active_thread->name, my_active_thread->pid);
}
#endif
#ifdef SCHEDSTATISTICS
if (sched_pidlist[my_active_thread->pid].laststart) {
sched_pidlist[my_active_thread->pid].runtime_ticks += time - sched_pidlist[my_active_thread->pid].laststart;
}
#endif
}
DEBUG("\nscheduler: previous task: %s\n", (my_active_thread == NULL) ? "none" : my_active_thread->name);
/* The bitmask in runqueue_bitcache is never empty,
* since the threading should not be started before at least the idle thread was started.
*/
int nextrq = bitarithm_lsb(runqueue_bitcache);
clist_node_t next = *(sched_runqueues[nextrq]);
DEBUG("scheduler: first in queue: %s\n", ((tcb_t *)next.data)->name);
clist_advance(&(sched_runqueues[nextrq]));
my_active_thread = (tcb_t *)next.data;
int my_next_pid = my_active_thread->pid;
#if SCHEDSTATISTICS
sched_pidlist[my_next_pid].laststart = time;
sched_pidlist[my_next_pid].schedules++;
if ((sched_cb) && (my_next_pid != sched_active_pid)) {
sched_cb(time, my_next_pid);
}
#endif
sched_active_pid = my_next_pid;
DEBUG("scheduler: next task: %s\n", my_active_thread->name);
if (my_active_thread != sched_active_thread) {
if (sched_active_thread != NULL) {
if (sched_active_thread->status == STATUS_RUNNING) {
sched_active_thread->status = STATUS_PENDING;
}
}
sched_set_status((tcb_t *)my_active_thread, STATUS_RUNNING);
}
sched_active_thread = (volatile tcb_t *) my_active_thread;
DEBUG("scheduler: done.\n");
}
#if SCHEDSTATISTICS
void sched_register_cb(void (*callback)(uint32_t, uint32_t))
{
sched_cb = callback;
}
#endif
void sched_set_status(tcb_t *process, unsigned int status)
{
if (status >= STATUS_ON_RUNQUEUE) {
if (!(process->status >= STATUS_ON_RUNQUEUE)) {
DEBUG("adding process %s to runqueue %u.\n", process->name, process->priority);
clist_add(&sched_runqueues[process->priority], &(process->rq_entry));
runqueue_bitcache |= 1 << process->priority;
}
}
else {
if (process->status >= STATUS_ON_RUNQUEUE) {
DEBUG("removing process %s from runqueue %u.\n", process->name, process->priority);
clist_remove(&sched_runqueues[process->priority], &(process->rq_entry));
if (!sched_runqueues[process->priority]) {
runqueue_bitcache &= ~(1 << process->priority);
}
}
}
process->status = status;
}
void sched_switch(uint16_t other_prio)
{
int in_isr = inISR();
uint16_t current_prio = sched_active_thread->priority;
DEBUG("%s: %" PRIu16 " %" PRIu16 " %i\n", sched_active_thread->name, current_prio, other_prio, in_isr);
if (current_prio >= other_prio) {
if (in_isr) {
sched_context_switch_request = 1;
}
else {
thread_yield();
}
}
}
NORETURN void sched_task_exit(void)
{
DEBUG("sched_task_exit(): ending task %s...\n", sched_active_thread->name);
dINT();
sched_threads[sched_active_thread->pid] = NULL;
sched_num_threads--;
sched_set_status((tcb_t *)sched_active_thread, STATUS_STOPPED);
sched_active_thread = NULL;
cpu_switch_context_exit();
}