Implement some more functions in terms of macros.

[mLib] / tv.c

/* -*-c-*-
 *
 * $Id: tv.c,v 1.4 1999/05/17 20:37:52 mdw Exp $
 *
 * Manipulation of timeval structures
 *
 * (c) 1998 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------* 
 *
 * This file is part of the mLib utilities library.
 *
 * mLib is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 * 
 * mLib is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Library General Public License for more details.
 * 
 * You should have received a copy of the GNU Library General Public
 * License along with mLib; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

/*----- Revision history --------------------------------------------------* 
 *
 * $Log: tv.c,v $
 * Revision 1.4  1999/05/17 20:37:52  mdw
 * New function `tv_addl' to add a literal to a time value.  Use magical
 * `MILLION' constant in place of 1000000 for ease of reading.
 *
 * Revision 1.3  1999/05/06 19:51:36  mdw
 * Reformatted the LGPL notice a little bit.
 *
 * Revision 1.2  1999/05/05 18:50:31  mdw
 * Change licensing conditions to LGPL.
 *
 * Revision 1.1  1998/11/25 23:30:01  mdw
 * New file.
 *
 */

/*----- Header files ------------------------------------------------------*/

#include <sys/time.h>
#include "tv.h"

/*----- A macro to make reading easier ------------------------------------*/

#define MILLION 1000000

/*----- Main code ---------------------------------------------------------*/

/* --- @tv_add@ --- *
 *
 * Arguments:	@struct timeval *dst@ = destination block
 *		@const struct timeval *a, *b@ = source blocks
 *
 * Returns:	---
 *
 * Use:		Adds two timevals.
 */

void tv_add(struct timeval *dst,
	    const struct timeval *a, const struct timeval *b)
{
  dst->tv_sec = a->tv_sec + b->tv_sec;
  dst->tv_usec = a->tv_usec + b->tv_usec;
  if (dst->tv_usec >= MILLION) {
    dst->tv_usec -= MILLION;
    dst->tv_sec++;
  }
}

/* --- @tv_addl@ --- *
 *
 * Arguments:	@struct timeval *dst@ = destination block
 *		@const struct timeval *a@ = source blocks
 *		@time_t sec@, @unsigned long usec@ = time to add
 *
 * Returns:	---
 *
 * Use:		Adds a literal time in seconds and microseconds.
 */

void tv_addl(struct timeval *dst, const struct timeval *a,
	     time_t sec, unsigned long usec)
{
  dst->tv_sec = a->tv_sec + sec;
  dst->tv_usec = a->tv_usec + usec;
  if (dst->tv_usec >= MILLION) {
    dst->tv_usec -= MILLION;
    dst->tv_sec++;
  }
}

/* --- @tv_sub@ --- *
 *
 * Arguments:	@struct timeval *dst@ = destination block
 *		@const struct timeval *a, *b@ = source blocks
 *
 * Returns:	---
 *
 * Use:		Subtracts two timevals.
 */

void tv_sub(struct timeval *dst,
	    const struct timeval *a, const struct timeval *b)
{
  dst->tv_sec = a->tv_sec - b->tv_sec;
  if (a->tv_usec >= b->tv_usec)
    dst->tv_usec = a->tv_usec - b->tv_usec;
  else {
    dst->tv_usec = a->tv_usec + MILLION - b->tv_usec;
    dst->tv_sec--;
  }
}

/* --- @tv_cmp@ --- *
 *
 * Arguments:	@const struct timeval *a, *b@ = source blocks
 *
 * Returns:	Less than, equal to, or greater than zero.
 *
 * Use:		Compares two timevals.
 */

int tv_cmp(const struct timeval *a, const struct timeval *b)
{
  if (a->tv_sec > b->tv_sec)
    return (1);
  else if (a->tv_sec < b->tv_sec)
    return (-1);
  else if (a->tv_usec > b->tv_usec)
    return (1);
  else if (a->tv_usec < b->tv_usec)
    return (-1);
  else
    return (0);
}

/*----- That's all, folks -------------------------------------------------*/