tests/test-count-trailing-zeros.c

   1 /* Test counting of trailing zeros.
   2    Copyright (C) 2013-2020 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 /* Written by Paul Eggert.  */
  18
  19 #include <config.h>
  20
  21 #include "count-trailing-zeros.h"
  22
  23 #include <limits.h>
  24 #include <stdio.h>
  25
  26 #include "macros.h"
  27
  28 #define UINT_BIT (sizeof (unsigned int) * CHAR_BIT)
  29 #define ULONG_BIT (sizeof (unsigned long int) * CHAR_BIT)
  30 #define ULLONG_BIT (sizeof (unsigned long long int) * CHAR_BIT)
  31
  32 int
  33 main (int argc, char *argv[])
  34 {
  35   int i, j;
  36
  37 #define TEST_COUNT_TRAILING_ZEROS(FUNC, TYPE, BITS, MAX, ONE) \
  38   ASSERT (FUNC (0) == BITS);                                  \
  39   for (i = 0; i < BITS; i++)                                  \
  40     {                                                         \
  41       ASSERT (FUNC (ONE << i) == i);                          \
  42       for (j = 0; j < i; j++)                                 \
  43         ASSERT (FUNC ((ONE << i) | (ONE << j)) == j);         \
  44     }                                                         \
  45   for (i = 0; i < 1000; i++)                                  \
  46     {                                                         \
  47       /* RAND_MAX is most often 0x7fff or 0x7fffffff.  */     \
  48       TYPE value =                                            \
  49         (RAND_MAX <= 0xffff                                   \
  50          ? ((TYPE) rand () >> 3)                              \
  51            ^ (((TYPE) rand () >> 3) << 12)                    \
  52            ^ (((TYPE) rand () >> 3) << 24)                    \
  53            ^ (((TYPE) rand () >> 3) << 30 << 6)               \
  54            ^ (((TYPE) rand () >> 3) << 30 << 18)              \
  55            ^ (((TYPE) rand () >> 3) << 30 << 30)              \
  56          : ((TYPE) rand () >> 3)                              \
  57            ^ (((TYPE) rand () >> 3) << 22)                    \
  58            ^ (((TYPE) rand () >> 3) << 22 << 22));            \
  59       int count = 0;                                          \
  60       for (j = BITS - 1; 0 <= j; j--)                         \
  61         if (value & (ONE << j))                               \
  62           count = j;                                          \
  63       ASSERT (count == FUNC (value));                         \
  64     }                                                         \
  65   ASSERT (FUNC (MAX) == 0);
  66
  67   TEST_COUNT_TRAILING_ZEROS (count_trailing_zeros, unsigned int,
  68                              UINT_BIT, UINT_MAX, 1U);
  69   TEST_COUNT_TRAILING_ZEROS (count_trailing_zeros_l, unsigned long int,
  70                              ULONG_BIT, ULONG_MAX, 1UL);
  71   TEST_COUNT_TRAILING_ZEROS (count_trailing_zeros_ll, unsigned long long int,
  72                              ULLONG_BIT, ULLONG_MAX, 1ULL);
  73
  74   return 0;
  75 }