tests/test-count-leading-zeros.c

   1 /*
   2  * Copyright (C) 2012-2024 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 /* Written by Eric Blake.  */
  18
  19 #include <config.h>
  20
  21 #include "count-leading-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_LEADING_ZEROS(FUNC, TYPE, BITS, MAX, ONE)     \
  38   ASSERT (FUNC (0) == BITS);                                     \
  39   for (i = 0; i < BITS; i++)                                     \
  40     {                                                            \
  41       ASSERT (FUNC (ONE << i) == BITS - i - 1);                  \
  42       for (j = 0; j < i; j++)                                    \
  43         ASSERT (FUNC ((ONE << i) | (ONE << j)) == BITS - i - 1); \
  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 = 0; j < BITS; j++)                                 \
  61         if (value & (ONE << j))                                  \
  62           count = BITS - j - 1;                                  \
  63       ASSERT (count == FUNC (value));                            \
  64     }                                                            \
  65   ASSERT (FUNC (MAX) == 0);
  66
  67   TEST_COUNT_LEADING_ZEROS (count_leading_zeros, unsigned int,
  68                             UINT_BIT, UINT_MAX, 1U);
  69   TEST_COUNT_LEADING_ZEROS (count_leading_zeros_l, unsigned long int,
  70                             ULONG_BIT, ULONG_MAX, 1UL);
  71   TEST_COUNT_LEADING_ZEROS (count_leading_zeros_ll, unsigned long long int,
  72                             ULLONG_BIT, ULLONG_MAX, 1ULL);
  73
  74   return test_exit_status;
  75 }