kc3-lang/gnulib/tests/test-ffs.c

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• Hash : 32a72f45
  Author :
  Date : 2023-01-01T01:14:21
  

  maint: run 'make update-copyright'
  

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• tests/test-ffs.c

• /*
   * Copyright (C) 2011-2023 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 Eric Blake.  */
  #include <config.h>
  
  #include <strings.h>
  
  #include "signature.h"
  SIGNATURE_CHECK (ffs, int, (int));
  
  #include <limits.h>
  
  #include "macros.h"
  
  #define NBITS (sizeof (int) * CHAR_BIT)
  
  static int
  naive (int i)
  {
    unsigned int j;
    for (j = 0; j < NBITS; j++)
      if (i & (1U << j))
        return j + 1;
    return 0;
  }
  
  int
  main (int argc, char *argv[])
  {
    int x;
    int i;
  
    for (x = -128; x <= 128; x++)
      ASSERT (ffs (x) == naive (x));
    for (i = 0; i < NBITS; i++)
      {
        ASSERT (ffs (1U << i) == naive (1U << i));
        ASSERT (ffs (1U << i) == i + 1);
        ASSERT (ffs (-1U << i) == i + 1);
      }
    for (i = 0; i < NBITS - 1; i++)
      {
        ASSERT (ffs (3U << i) == i + 1);
        ASSERT (ffs (-3U << i) == i + 1);
      }
    for (i = 0; i < NBITS - 2; i++)
      {
        ASSERT (ffs (5U << i) == i + 1);
        ASSERT (ffs (-5U << i) == i + 1);
        ASSERT (ffs (7U << i) == i + 1);
        ASSERT (ffs (-7U << i) == i + 1);
      }
    return 0;
  }
  

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