time_util.h

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/*
 * time_util.h
 *
 * Copyright (c) 2003 The University of Utah and the Flux Group.
 * All rights reserved.
 *
 * This file is licensed under the terms of the GNU Public License.  
 * See the file "license.terms" for restrictions on redistribution 
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 */

/**
 * @file time_util.h
 *
 * Inline functions for manipulating time values.
 */

#ifndef _time_util_h
#define _time_util_h

#ifdef __cplusplus
extern "C" {
#endif

#include "assert_pp.h"

/**
 * The number of microseconds per second.
 */
#define MICROS_PER_SECOND 1000000

/**
 * The number of nanoseconds per microsecond.
 */
#define NANOS_PER_MICRO 1000

/**
 * Convert a microsecond value to a struct timespec.
 *
 * @param microseconds The microsecond value to convert.
 * @return A timespec that represents the given number of microseconds.
 */
static inline
struct timespec microsec_to_timespec(unsigned long long microseconds)
{
    struct timespec retval;
    
    retval.tv_sec =  (int)(microseconds / MICROS_PER_SECOND);
    retval.tv_nsec = (int)(microseconds % MICROS_PER_SECOND) * NANOS_PER_MICRO;
    return retval;
}

/**
 * Convert a timespec to a microsecond value.  @e NOTE: There is a loss of
 * precision in the conversion.
 *
 * @param time_spec The timespec to convert.
 * @return The number of microseconds specified by the timespec.
 */
static inline
unsigned long long timespec_to_microsec(struct timespec *time_spec)
{
    long long retval;

    require(time_spec != 0);
    
    retval = time_spec->tv_sec * MICROS_PER_SECOND;
    retval += time_spec->tv_nsec / NANOS_PER_MICRO;
    return retval;
}

/**
 * Convert a string to a microsecond value.  The string format is a number
 * followed by an optional unit notation, where microseconds is the default
 * unit.  For example:
 *
 * @li 10 = 10 microseconds
 * @li 10us = 10 microseconds
 * @li 10ms = 10,000 microseconds
 * @li 10s = 10,000,000 microseconds
 *
 * @param us_out The destination for the microsecond value.
 * @param str The string to parse.
 * @return True if the string was successfully parsed, false otherwise.
 */
int string_to_microsec(unsigned long long *us_out, const char *str);

/**
 * Compare two timespec's.
 *
 * @param tvp Pointer to the first timespec.
 * @param uvp Pointer to the second timespec.
 * @param cmp The comparison operator.
 */
#define tscmp(tvp, uvp, cmp)                                            \
        (((tvp)->tv_sec == (uvp)->tv_sec) ?                             \
            ((tvp)->tv_nsec cmp (uvp)->tv_nsec) :                       \
            ((tvp)->tv_sec cmp (uvp)->tv_sec))

#ifdef __cplusplus
}
#endif

#endif

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