/****************************************************************************
 *
 *   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,
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 ****************************************************************************/

/**
 * @file perf_counter.h
 * Performance measuring tools.
 */

#ifndef _SYSTEMLIB_PERF_COUNTER_H
#define _SYSTEMLIB_PERF_COUNTER_H value

#include <stdint.h>

/**
 * Counter types.
 */
enum perf_counter_type {
	PC_COUNT,		/**< count the number of times an event occurs */
	PC_ELAPSED,		/**< measure the time elapsed performing an event */
	PC_INTERVAL		/**< measure the interval between instances of an event */
};

struct perf_ctr_header;
typedef struct perf_ctr_header	*perf_counter_t;

__BEGIN_DECLS

/**
 * Create a new counter.
 *
 * @param type			The type of the new counter.
 * @param name			The counter name.
 * @return			Handle for the new counter, or NULL if a counter
 *				could not be allocated.
 */
__EXPORT extern perf_counter_t	perf_alloc(enum perf_counter_type type, const char *name);

/**
 * Free a counter.
 *
 * @param handle		The performance counter's handle.
 */
__EXPORT extern void		perf_free(perf_counter_t handle);

/**
 * Count a performance event.
 *
 * This call only affects counters that take single events; PC_COUNT, PC_INTERVAL etc.
 *
 * @param handle		The handle returned from perf_alloc.
 */
__EXPORT extern void		perf_count(perf_counter_t handle);

/**
 * Begin a performance event.
 *
 * This call applies to counters that operate over ranges of time; PC_ELAPSED etc.
 *
 * @param handle		The handle returned from perf_alloc.
 */
__EXPORT extern void		perf_begin(perf_counter_t handle);

/**
 * End a performance event.
 *
 * This call applies to counters that operate over ranges of time; PC_ELAPSED etc.
 * If a call is made without a corresopnding perf_begin call, or if perf_cancel
 * has been called subsequently, no change is made to the counter.
 *
 * @param handle		The handle returned from perf_alloc.
 */
__EXPORT extern void		perf_end(perf_counter_t handle);

/**
 * Cancel a performance event.
 *
 * This call applies to counters that operate over ranges of time; PC_ELAPSED etc.
 * It reverts the effect of a previous perf_begin.
 *
 * @param handle		The handle returned from perf_alloc.
 */
__EXPORT extern void		perf_cancel(perf_counter_t handle);

/**
 * Reset a performance counter.
 *
 * This call resets performance counter to initial state
 *
 * @param handle		The handle returned from perf_alloc.
 */
__EXPORT extern void		perf_reset(perf_counter_t handle);

/**
 * Print one performance counter to stdout
 *
 * @param handle		The counter to print.
 */
__EXPORT extern void		perf_print_counter(perf_counter_t handle);

/**
 * Print one performance counter to a fd.
 *
 * @param fd			File descriptor to print to - e.g. 0 for stdout
 * @param handle		The counter to print.
 */
__EXPORT extern void		perf_print_counter_fd(int fd, perf_counter_t handle);

/**
 * Print all of the performance counters.
 *
 * @param fd			File descriptor to print to - e.g. 0 for stdout
 */
__EXPORT extern void		perf_print_all(int fd);

/**
 * Reset all of the performance counters.
 */
__EXPORT extern void		perf_reset_all(void);

/**
 * Return current event_count
 *
 * @param handle		The counter returned from perf_alloc.
 * @return			event_count
 */
__EXPORT extern uint64_t	perf_event_count(perf_counter_t handle);

__END_DECLS

#endif