kc3-lang/gnulib/lib/timespec-sub.c

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• Hash : b021c53f
  Author :
  Date : 2018-09-10T18:42:25
  

  timespec: fix resolution confusion
  
  In normal usage, clock resolution is given in seconds, but the
  code was mistakenly using inverse seconds and calling it
  “resolution”.  Fix this, partly by renaming two identifiers.
  The old names will be kept for a bit, to ease transition.
  * lib/timespec.h (TIMESPEC_HZ, LOG10_TIMESPEC_HZ):
  New constants, replacing TIMESPEC_RESOLUTION and
  LOG10_TIMESPEC_RESOLUTION, which are now obsolescent.
  All uses changed.
  

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• lib/timespec-sub.c

• /* Subtract two struct timespec values.
  
     Copyright (C) 2011-2018 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 3 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, see <https://www.gnu.org/licenses/>.  */
  
  /* Written by Paul Eggert.  */
  
  /* Return the difference between two timespec values A and B.  On
     overflow, return an extremal value.  This assumes 0 <= tv_nsec <
     TIMESPEC_HZ.  */
  
  #include <config.h>
  #include "timespec.h"
  
  #include "intprops.h"
  
  struct timespec
  timespec_sub (struct timespec a, struct timespec b)
  {
    time_t rs = a.tv_sec;
    time_t bs = b.tv_sec;
    int ns = a.tv_nsec - b.tv_nsec;
    int rns = ns;
    time_t tmin = TYPE_MINIMUM (time_t);
    time_t tmax = TYPE_MAXIMUM (time_t);
  
    if (ns < 0)
      {
        rns = ns + TIMESPEC_HZ;
        if (bs < tmax)
          bs++;
        else if (- TYPE_SIGNED (time_t) < rs)
          rs--;
        else
          goto low_overflow;
      }
  
    /* INT_SUBTRACT_WRAPV is not appropriate since time_t might be unsigned.
       In theory time_t might be narrower than int, so plain
       INT_SUBTRACT_OVERFLOW does not suffice.  */
    if (! INT_SUBTRACT_OVERFLOW (rs, bs) && tmin <= rs - bs && rs - bs <= tmax)
      rs -= bs;
    else
      {
        if (rs < 0)
          {
          low_overflow:
            rs = tmin;
            rns = 0;
          }
        else
          {
            rs = tmax;
            rns = TIMESPEC_HZ - 1;
          }
      }
  
    return make_timespec (rs, rns);
  }
  

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