| 1 | /* struct timeval subtraction. |
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| 2 | Copyright (C) 1991-2024 Free Software Foundation, Inc. |
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| 3 | |
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| 4 | This program is free software; you can redistribute it and/or |
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| 5 | modify it under the terms of the GNU General Public License |
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| 6 | as published by the Free Software Foundation; either version 2 |
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| 7 | of the License, or (at your option) any later version. |
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| 8 | |
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| 9 | This program is distributed in the hope that it will be useful, |
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 12 | GNU General Public License for more details. |
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| 13 | |
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| 14 | You should have received a copy of the GNU General Public License |
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| 15 | along with this program; if not, see <https://www.gnu.org/licenses/>. |
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| 16 | */ |
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| 17 | |
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| 18 | /* Subtract the `struct timeval' values X and Y, |
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| 19 | storing the result in RESULT. |
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| 20 | Return 1 if the difference is negative, otherwise 0. */ |
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| 21 | |
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| 22 | int |
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| 23 | timeval_subtract (struct timeval *result, struct timeval *x, struct timeval *y) |
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| 24 | { |
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| 25 | /* Perform the carry for the later subtraction by updating @var{y}. */ |
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| 26 | if (x->tv_usec < y->tv_usec) { |
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| 27 | int nsec = (y->tv_usec - x->tv_usec) / 1000000 + 1; |
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| 28 | y->tv_usec -= 1000000 * nsec; |
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| 29 | y->tv_sec += nsec; |
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| 30 | } |
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| 31 | if (x->tv_usec - y->tv_usec > 1000000) { |
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| 32 | int nsec = (x->tv_usec - y->tv_usec) / 1000000; |
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| 33 | y->tv_usec += 1000000 * nsec; |
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| 34 | y->tv_sec -= nsec; |
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| 35 | } |
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| 36 | |
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| 37 | /* Compute the time remaining to wait. |
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| 38 | @code{tv_usec} is certainly positive. */ |
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| 39 | result->tv_sec = x->tv_sec - y->tv_sec; |
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| 40 | result->tv_usec = x->tv_usec - y->tv_usec; |
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| 41 | |
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| 42 | /* Return 1 if result is negative. */ |
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| 43 | return x->tv_sec < y->tv_sec; |
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| 44 | } |
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| 45 | |
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