| /* struct timeval subtraction. |
| Copyright (C) 1991-2014 Free Software Foundation, Inc. |
| |
| This program is free software; you can redistribute it and/or |
| modify it under the terms of the GNU General Public License |
| as published by the Free Software Foundation; either version 2 |
| of the License, or (at your option) any later version. |
| |
| This program 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 General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program; if not, if not, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| /* Subtract the `struct timeval' values X and Y, |
| storing the result in RESULT. |
| Return 1 if the difference is negative, otherwise 0. */ |
| |
| int |
| timeval_subtract (result, x, y) |
| struct timeval *result, *x, *y; |
| { |
| /* Perform the carry for the later subtraction by updating @var{y}. */ |
| if (x->tv_usec < y->tv_usec) { |
| int nsec = (y->tv_usec - x->tv_usec) / 1000000 + 1; |
| y->tv_usec -= 1000000 * nsec; |
| y->tv_sec += nsec; |
| } |
| if (x->tv_usec - y->tv_usec > 1000000) { |
| int nsec = (x->tv_usec - y->tv_usec) / 1000000; |
| y->tv_usec += 1000000 * nsec; |
| y->tv_sec -= nsec; |
| } |
| |
| /* Compute the time remaining to wait. |
| @code{tv_usec} is certainly positive. */ |
| result->tv_sec = x->tv_sec - y->tv_sec; |
| result->tv_usec = x->tv_usec - y->tv_usec; |
| |
| /* Return 1 if result is negative. */ |
| return x->tv_sec < y->tv_sec; |
| } |