ardupilot/libraries/AP_Scheduler/AP_Scheduler.cpp

154 lines
5.2 KiB
C++
Raw Normal View History

/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
This program 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.
This program 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/>.
*/
/*
* main loop scheduler for APM
* Author: Andrew Tridgell, January 2013
*
*/
#include <AP_HAL/AP_HAL.h>
#include "AP_Scheduler.h"
#include <AP_Param/AP_Param.h>
extern const AP_HAL::HAL& hal;
int8_t AP_Scheduler::current_task = -1;
const AP_Param::GroupInfo AP_Scheduler::var_info[] PROGMEM = {
// @Param: DEBUG
// @DisplayName: Scheduler debug level
2013-08-30 02:33:30 -03:00
// @Description: Set to non-zero to enable scheduler debug messages. When set to show "Slips" the scheduler will display a message whenever a scheduled task is delayed due to too much CPU load. When set to ShowOverruns the scheduled will display a message whenever a task takes longer than the limit promised in the task table.
2013-10-13 07:39:33 -03:00
// @Values: 0:Disabled,2:ShowSlips,3:ShowOverruns
// @User: Advanced
AP_GROUPINFO("DEBUG", 0, AP_Scheduler, _debug, 0),
AP_GROUPEND
};
// initialise the scheduler
void AP_Scheduler::init(const AP_Scheduler::Task *tasks, uint8_t num_tasks)
{
_tasks = tasks;
_num_tasks = num_tasks;
_last_run = new uint16_t[_num_tasks];
memset(_last_run, 0, sizeof(_last_run[0]) * _num_tasks);
_tick_counter = 0;
}
// one tick has passed
void AP_Scheduler::tick(void)
{
_tick_counter++;
}
/*
run one tick
this will run as many scheduler tasks as we can in the specified time
*/
void AP_Scheduler::run(uint16_t time_available)
{
uint32_t run_started_usec = hal.scheduler->micros();
uint32_t now = run_started_usec;
for (uint8_t i=0; i<_num_tasks; i++) {
uint16_t dt = _tick_counter - _last_run[i];
uint16_t interval_ticks = pgm_read_word(&_tasks[i].interval_ticks);
if (dt >= interval_ticks) {
// this task is due to run. Do we have enough time to run it?
_task_time_allowed = pgm_read_word(&_tasks[i].max_time_micros);
if (dt >= interval_ticks*2) {
// we've slipped a whole run of this task!
if (_debug > 1) {
hal.console->printf_P(PSTR("Scheduler slip task[%u-%s] (%u/%u/%u)\n"),
(unsigned)i,
_tasks[i].name,
(unsigned)dt,
(unsigned)interval_ticks,
(unsigned)_task_time_allowed);
}
}
if (_task_time_allowed <= time_available) {
// run it
_task_time_started = now;
task_fn_t func;
pgm_read_block(&_tasks[i].function, &func, sizeof(func));
current_task = i;
2015-05-24 18:55:06 -03:00
func();
current_task = -1;
// record the tick counter when we ran. This drives
// when we next run the event
_last_run[i] = _tick_counter;
// work out how long the event actually took
now = hal.scheduler->micros();
uint32_t time_taken = now - _task_time_started;
if (time_taken > _task_time_allowed) {
// the event overran!
if (_debug > 2) {
hal.console->printf_P(PSTR("Scheduler overrun task[%u-%s] (%u/%u)\n"),
(unsigned)i,
_tasks[i].name,
(unsigned)time_taken,
(unsigned)_task_time_allowed);
}
}
if (time_taken >= time_available) {
goto update_spare_ticks;
}
time_available -= time_taken;
}
}
}
// update number of spare microseconds
_spare_micros += time_available;
update_spare_ticks:
_spare_ticks++;
if (_spare_ticks == 32) {
_spare_ticks /= 2;
_spare_micros /= 2;
}
}
/*
return number of micros until the current task reaches its deadline
*/
uint16_t AP_Scheduler::time_available_usec(void)
{
uint32_t dt = hal.scheduler->micros() - _task_time_started;
if (dt > _task_time_allowed) {
return 0;
}
return _task_time_allowed - dt;
}
/*
calculate load average as a number from 0 to 1
*/
float AP_Scheduler::load_average(uint32_t tick_time_usec) const
{
2013-08-02 09:07:00 -03:00
if (_spare_ticks == 0) {
return 0.0f;
}
uint32_t used_time = tick_time_usec - (_spare_micros/_spare_ticks);
return used_time / (float)tick_time_usec;
}