diff options
Diffstat (limited to 'apps/drivers/drv_hrt.h')
-rw-r--r-- | apps/drivers/drv_hrt.h | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/apps/drivers/drv_hrt.h b/apps/drivers/drv_hrt.h new file mode 100644 index 000000000..a6d501f53 --- /dev/null +++ b/apps/drivers/drv_hrt.h @@ -0,0 +1,133 @@ +/**************************************************************************** + * + * Copyright (C) 2012 PX4 Development Team. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. Neither the name PX4 nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + ****************************************************************************/ + +/** + * @file drv_hrt.h + * + * High-resolution timer with callouts and timekeeping. + */ + +#pragma once + +#include <sys/types.h> +#include <stdbool.h> + +#include <time.h> +#include <queue.h> + +__BEGIN_DECLS + +/* + * Absolute time, in microsecond units. + * + * Absolute time is measured from some arbitrary epoch shortly after + * system startup. It should never wrap or go backwards. + */ +typedef uint64_t hrt_abstime; + +/* + * Callout function type. + * + * Note that callouts run in the timer interrupt context, so + * they are serialised with respect to each other, and must not + * block. + */ +typedef void (* hrt_callout)(void *arg); + +/* + * Callout record. + */ +typedef struct hrt_call { + struct sq_entry_s link; + + hrt_abstime deadline; + hrt_abstime period; + hrt_callout callout; + void *arg; +} *hrt_call_t; + +/* + * Get absolute time. + */ +__EXPORT extern hrt_abstime hrt_absolute_time(void); + +/* + * Convert a timespec to absolute time. + */ +__EXPORT extern hrt_abstime ts_to_abstime(struct timespec *ts); + +/* + * Convert absolute time to a timespec. + */ +__EXPORT extern void abstime_to_ts(struct timespec *ts, hrt_abstime abstime); + +/* + * Call callout(arg) after delay has elapsed. + * + * If callout is NULL, this can be used to implement a timeout by testing the call + * with hrt_called(). + */ +__EXPORT extern void hrt_call_after(struct hrt_call *entry, hrt_abstime delay, hrt_callout callout, void *arg); + +/* + * Call callout(arg) at absolute time calltime. + */ +__EXPORT extern void hrt_call_at(struct hrt_call *entry, hrt_abstime calltime, hrt_callout callout, void *arg); + +/* + * Call callout(arg) after delay, and then after every interval. + * + * Note thet the interval is timed between scheduled, not actual, call times, so the call rate may + * jitter but should not drift. + */ +__EXPORT extern void hrt_call_every(struct hrt_call *entry, hrt_abstime delay, hrt_abstime interval, hrt_callout callout, void *arg); + +/* + * If this returns true, the entry has been invoked and removed from the callout list, + * or it has never been entered. + * + * Always returns false for repeating callouts. + */ +__EXPORT extern bool hrt_called(struct hrt_call *entry); + +/* + * Remove the entry from the callout list. + */ +__EXPORT extern void hrt_cancel(struct hrt_call *entry); + +/* + * Initialise the HRT. + */ +__EXPORT extern void hrt_init(void); + +__END_DECLS |