/*

 * SPDX-License-Identifier: ISC

 *

 * Copyright (c) 2019-2020 Todd C. Miller <Todd.Miller@sudo.ws>

 *

 * Permission to use, copy, modify, and distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR

 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN

 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF

 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

 */

#include <config.h>

#include <sudo_compat.h>

#include <sudo_debug.h>

#include <sudo_util.h>

/*

 * Round 32-bit unsigned length to the next highest power of two.

 * Always returns at least 64.

 */

unsigned int

sudo_pow2_roundup_v1(unsigned int len)

{

    if (len < 64)

  return 64;

#ifdef HAVE___BUILTIN_CLZ

    return 1U << (32 - __builtin_clz(len - 1));

#else

    len--;

    len |= len >> 1;

    len |= len >> 2;

    len |= len >> 4;

    len |= len >> 8;

    len |= len >> 16;

    len++;

    return len;

#endif

}

/*

 * Round a size_t length to the next highest power of two.

 * Always returns at least 64.

 */

size_t

sudo_pow2_roundup_v2(size_t len)

{

    if (len < 64)

  return 64;

#if defined(__LP64__) && defined(HAVE___BUILTIN_CLZL)

    return 1UL << (64 - __builtin_clzl(len - 1));

#elif !defined(__LP64__) && defined(HAVE___BUILTIN_CLZ)

    return 1U << (32 - __builtin_clz(len - 1));

#else

    len--;

    len |= len >> 1;

    len |= len >> 2;

    len |= len >> 4;

    len |= len >> 8;

    len |= len >> 16;

# ifdef __LP64__

    len |= len >> 32;

# endif

    len++;

    return len;

#endif

}