tests/test-integer_length_ll.c

   1 /* Test of integer_length_ll().
   2    Copyright (C) 2011-2024 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18
  19 #include "integer_length.h"
  20
  21 #include <limits.h>
  22
  23 #include "macros.h"
  24
  25 #define NBITS (sizeof (unsigned long long) * CHAR_BIT)
  26
  27 static int
  28 naive (unsigned long long x)
  29 {
  30   int j;
  31   for (j = NBITS - 1; j >= 0; j--)
  32     if (x & (1ULL << j))
  33       return j + 1;
  34   return 0;
  35 }
  36
  37 int
  38 main (int argc, char *argv[])
  39 {
  40   unsigned long x;
  41   int i;
  42
  43   for (x = 0; x <= 256; x++)
  44     ASSERT (integer_length_ll (x) == naive (x));
  45   for (i = 0; i < NBITS; i++)
  46     {
  47       ASSERT (integer_length_ll (1ULL << i) == naive (1ULL << i));
  48       ASSERT (integer_length_ll (1ULL << i) == i + 1);
  49       ASSERT (integer_length_ll (-1ULL << i) == NBITS);
  50     }
  51   for (i = 0; i < NBITS - 1; i++)
  52     ASSERT (integer_length_ll (3ULL << i) == i + 2);
  53   for (i = 0; i < NBITS - 2; i++)
  54     ASSERT (integer_length_ll (-3ULL << i) == NBITS);
  55   for (i = 0; i < NBITS - 2; i++)
  56     {
  57       ASSERT (integer_length_ll (5ULL << i) == i + 3);
  58       ASSERT (integer_length_ll (7ULL << i) == i + 3);
  59     }
  60   for (i = 0; i < NBITS - 3; i++)
  61     {
  62       ASSERT (integer_length_ll (-5ULL << i) == NBITS);
  63       ASSERT (integer_length_ll (-7ULL << i) == NBITS);
  64     }
  65   return test_exit_status;
  66 }