mirror of https://github.com/ArduPilot/ardupilot
152 lines
5.1 KiB
C++
152 lines
5.1 KiB
C++
/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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/*
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This program 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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This program 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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* main loop scheduler for APM
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* Author: Andrew Tridgell, January 2013
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*
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*/
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#include <AP_HAL/AP_HAL.h>
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#include "AP_Scheduler.h"
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#include <AP_Param/AP_Param.h>
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extern const AP_HAL::HAL& hal;
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int8_t AP_Scheduler::current_task = -1;
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const AP_Param::GroupInfo AP_Scheduler::var_info[] PROGMEM = {
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// @Param: DEBUG
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// @DisplayName: Scheduler debug level
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// @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.
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// @Values: 0:Disabled,2:ShowSlips,3:ShowOverruns
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// @User: Advanced
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AP_GROUPINFO("DEBUG", 0, AP_Scheduler, _debug, 0),
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AP_GROUPEND
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};
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// initialise the scheduler
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void AP_Scheduler::init(const AP_Scheduler::Task *tasks, uint8_t num_tasks)
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{
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_tasks = tasks;
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_num_tasks = num_tasks;
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_last_run = new uint16_t[_num_tasks];
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memset(_last_run, 0, sizeof(_last_run[0]) * _num_tasks);
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_tick_counter = 0;
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}
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// one tick has passed
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void AP_Scheduler::tick(void)
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{
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_tick_counter++;
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}
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/*
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run one tick
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this will run as many scheduler tasks as we can in the specified time
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*/
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void AP_Scheduler::run(uint16_t time_available)
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{
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uint32_t run_started_usec = hal.scheduler->micros();
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uint32_t now = run_started_usec;
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for (uint8_t i=0; i<_num_tasks; i++) {
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uint16_t dt = _tick_counter - _last_run[i];
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uint16_t interval_ticks = pgm_read_word(&_tasks[i].interval_ticks);
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if (dt >= interval_ticks) {
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// this task is due to run. Do we have enough time to run it?
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_task_time_allowed = pgm_read_word(&_tasks[i].max_time_micros);
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if (dt >= interval_ticks*2) {
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// we've slipped a whole run of this task!
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if (_debug > 1) {
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hal.console->printf_P(PSTR("Scheduler slip task[%u] (%u/%u/%u)\n"),
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(unsigned)i,
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(unsigned)dt,
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(unsigned)interval_ticks,
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(unsigned)_task_time_allowed);
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}
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}
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if (_task_time_allowed <= time_available) {
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// run it
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_task_time_started = now;
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task_fn_t func;
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pgm_read_block(&_tasks[i].function, &func, sizeof(func));
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current_task = i;
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func();
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current_task = -1;
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// record the tick counter when we ran. This drives
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// when we next run the event
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_last_run[i] = _tick_counter;
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// work out how long the event actually took
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now = hal.scheduler->micros();
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uint32_t time_taken = now - _task_time_started;
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if (time_taken > _task_time_allowed) {
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// the event overran!
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if (_debug > 2) {
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hal.console->printf_P(PSTR("Scheduler overrun task[%u] (%u/%u)\n"),
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(unsigned)i,
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(unsigned)time_taken,
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(unsigned)_task_time_allowed);
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}
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}
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if (time_taken >= time_available) {
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goto update_spare_ticks;
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}
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time_available -= time_taken;
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}
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}
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}
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// update number of spare microseconds
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_spare_micros += time_available;
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update_spare_ticks:
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_spare_ticks++;
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if (_spare_ticks == 32) {
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_spare_ticks /= 2;
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_spare_micros /= 2;
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}
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}
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/*
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return number of micros until the current task reaches its deadline
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*/
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uint16_t AP_Scheduler::time_available_usec(void)
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{
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uint32_t dt = hal.scheduler->micros() - _task_time_started;
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if (dt > _task_time_allowed) {
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return 0;
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}
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return _task_time_allowed - dt;
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}
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/*
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calculate load average as a number from 0 to 1
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*/
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float AP_Scheduler::load_average(uint32_t tick_time_usec) const
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{
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if (_spare_ticks == 0) {
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return 0.0f;
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}
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uint32_t used_time = tick_time_usec - (_spare_micros/_spare_ticks);
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return used_time / (float)tick_time_usec;
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}
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