Hash :
32a72f45
Author :
Date :
2023-01-01T01:14:21
maint: run 'make update-copyright'
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68
/*
* 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;
}