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72 lines
1.7 KiB
C
72 lines
1.7 KiB
C
/* Add two struct timespec values.
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Copyright (C) 2011-2012 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* Written by Paul Eggert. */
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/* Return the sum of two timespec values A and B. On overflow, return
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an extremal value. This assumes 0 <= tv_nsec <= 999999999. */
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#include <config.h>
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#include "timespec.h"
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#include "intprops.h"
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struct timespec
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timespec_add (struct timespec a, struct timespec b)
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{
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struct timespec r;
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time_t rs = a.tv_sec;
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time_t bs = b.tv_sec;
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int ns = a.tv_nsec + b.tv_nsec;
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int nsd = ns - 1000000000;
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int rns = ns;
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if (0 <= nsd)
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{
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rns = nsd;
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if (rs == TYPE_MAXIMUM (time_t))
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{
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if (0 <= bs)
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goto high_overflow;
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bs++;
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}
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else
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rs++;
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}
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if (INT_ADD_OVERFLOW (rs, bs))
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{
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if (rs < 0)
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{
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rs = TYPE_MINIMUM (time_t);
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rns = 0;
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}
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else
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{
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high_overflow:
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rs = TYPE_MAXIMUM (time_t);
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rns = 999999999;
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}
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}
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else
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rs += bs;
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r.tv_sec = rs;
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r.tv_nsec = rns;
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return r;
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}
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