mirror of https://github.com/ArduPilot/ardupilot
113 lines
3.0 KiB
C
113 lines
3.0 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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/*
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High Resolution Timer code. This provides support for 32 and 64 bit
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returns for micros and millis functions
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*/
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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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#pragma GCC optimize("O2")
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/*
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we have 4 possible configurations of boards, made up of boards that
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have the following properties:
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CH_CFG_ST_RESOLUTION = 16 or 32
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CH_CFG_ST_FREQUENCY = 1000 or 1000000
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To keep as much code in common as possible we create a function
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system_time_u32_us() for all boards which gives system time since
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boot in microseconds, and which wraps at 0xFFFFFFFF.
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On top of this base function we build get_systime_us32() which has
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the same property, but which also maintains timer_base_us64 to allow
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for micros64()
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*/
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#if CH_CFG_ST_RESOLUTION == 16
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static uint32_t system_time_u32_us(void)
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{
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systime_t now = chVTGetSystemTimeX();
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#if CH_CFG_ST_FREQUENCY != 1000000U
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#error "must use 32 bit timer if system clock not 1MHz"
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#endif
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static systime_t last_systime;
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static uint32_t timer_base_us32;
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uint16_t dt = now - last_systime;
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last_systime = now;
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timer_base_us32 += dt;
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return timer_base_us32;
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}
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#elif CH_CFG_ST_RESOLUTION == 32
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static uint32_t system_time_u32_us(void)
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{
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systime_t now = chVTGetSystemTimeX();
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#if CH_CFG_ST_FREQUENCY != 1000000U
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now *= 1000000U/CH_CFG_ST_FREQUENCY;
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#endif
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return now;
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}
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#else
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#error "unsupported timer resolution"
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#endif
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// offset for micros64()
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static uint64_t timer_base_us64;
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static uint32_t get_systime_us32(void)
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{
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static uint32_t last_us32;
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uint32_t now = system_time_u32_us();
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if (now < last_us32) {
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const uint64_t dt_us = 0x100000000ULL;
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timer_base_us64 += dt_us;
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}
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last_us32 = now;
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return now;
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}
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/*
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for the exposed functions we use chSysGetStatusAndLockX() to prevent
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an interrupt changing the globals while allowing this call from any
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context
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*/
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uint64_t hrt_micros64()
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{
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syssts_t sts = chSysGetStatusAndLockX();
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uint32_t now = get_systime_us32();
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uint64_t ret = timer_base_us64 + now;
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chSysRestoreStatusX(sts);
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return ret;
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}
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uint32_t hrt_micros32()
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{
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syssts_t sts = chSysGetStatusAndLockX();
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uint32_t ret = get_systime_us32();
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chSysRestoreStatusX(sts);
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return ret;
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}
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uint32_t hrt_millis32()
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{
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return (uint32_t)(hrt_micros64() / 1000U);
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}
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