mirror of https://github.com/ArduPilot/ardupilot
48 lines
1.4 KiB
C
48 lines
1.4 KiB
C
/*
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* Copyright (C) Siddharth Bharat Purohit 2017
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* This file is free software: you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This file is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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// High Resolution Timer
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#include "ch.h"
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#include "hal.h"
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#include "hrt.h"
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#include <stdint.h>
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static uint64_t timer_base = 0;
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uint64_t hrt_micros()
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{
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static volatile uint64_t last_micros;
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/*
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use chSysGetStatusAndLockX() to prevent an interrupt while
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allowing this call from any context
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*/
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syssts_t sts = chSysGetStatusAndLockX();
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uint64_t micros;
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micros = timer_base + (uint64_t)chVTGetSystemTimeX();
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// we are doing this to avoid an additional interupt routing
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// since we are definitely going to get called atleast once in
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// a full timer period
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if (last_micros > micros) {
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const uint64_t step = ST2US(1ULL<<CH_CFG_ST_RESOLUTION);
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timer_base += step;
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micros += step;
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}
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last_micros = micros;
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chSysRestoreStatusX(sts);
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return micros;
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}
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