/* coap_time.h -- Clock Handling
 *
 * Copyright (C) 2010--2013 Olaf Bergmann <bergmann@tzi.org>
 *
 * This file is part of the CoAP library libcoap. Please see
 * README for terms of use.
 */

/**
 * @file coap_time.h
 * @brief Clock Handling
 */

#ifndef _COAP_TIME_H_
#define _COAP_TIME_H_

/*
** Make sure we can call this stuff from C++.
*/
#ifdef __cplusplus
extern "C" {
#endif


#include "coap_config.h"
//#include "system/sys_common.h" //TODO
/**
 * @defgroup clock Clock Handling
 * Default implementation of internal clock. You should redefine this if
 * you do not have time() and gettimeofday().
 * @{
 */
typedef unsigned int coap_tick_t;

/**
 * This data type is used to represent the difference between two
 * clock_tick_t values. This data type must have the same size in
 * memory as coap_tick_t to allow wrapping.
 */
typedef int coap_tick_diff_t;

#define COAP_TICKS_PER_SECOND 100

/** Set at startup to initialize the internal clock (time in seconds). */
extern time_t clock_offset;

#ifndef coap_clock_init
static inline void
coap_clock_init_impl(void)
{
    clock_offset = time(NULL);
}
#define coap_clock_init coap_clock_init_impl
#endif /* coap_clock_init */

extern int gettimeofday(struct timeval *tv, void *tz);

#ifndef coap_ticks
static inline void
coap_ticks_impl(coap_tick_t *t)
{
    struct timeval tv;
    gettimeofday(&tv, NULL);
    *t = (tv.tv_sec - clock_offset) * COAP_TICKS_PER_SECOND
         + (tv.tv_usec * COAP_TICKS_PER_SECOND / 1000000);
}
#define coap_ticks coap_ticks_impl
#endif /* coap_ticks */

/**
 * Returns @c 1 if and only if @p a is less than @p b where less is
 * defined on a signed data type.
 */
static inline
int coap_time_lt(coap_tick_t a, coap_tick_t b)
{
    return ((coap_tick_diff_t)(a - b)) < 0;
}

/**
 * Returns @c 1 if and only if @p a is less than or equal @p b where
 * less is defined on a signed data type.
 */
static inline
int coap_time_le(coap_tick_t a, coap_tick_t b)
{
    return a == b || coap_time_lt(a, b);
}

/** @} */

#ifdef __cplusplus
}
#endif


#endif /* _COAP_TIME_H_ */