Quelle count_zeros.h Sprache: C

/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Count leading and trailing zeros functions
*
* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/

#ifndef _LINUX_BITOPS_COUNT_ZEROS_H_
#define _LINUX_BITOPS_COUNT_ZEROS_H_

#include <asm/bitops.h>

/**
* count_leading_zeros - Count the number of zeros from the MSB back
* @x: The value
*
* Count the number of leading zeros from the MSB going towards the LSB in @x.
*
* If the MSB of @x is set, the result is 0.
* If only the LSB of @x is set, then the result is BITS_PER_LONG-1.
* If @x is 0 then the result is COUNT_LEADING_ZEROS_0.
*/
static inline int count_leading_zeros(unsigned long x)
{
if (sizeof(x) == 4)
  return BITS_PER_LONG - fls(x);
else
  return BITS_PER_LONG - fls64(x);
}

#define COUNT_LEADING_ZEROS_0 BITS_PER_LONG

/**
* count_trailing_zeros - Count the number of zeros from the LSB forwards
* @x: The value
*
* Count the number of trailing zeros from the LSB going towards the MSB in @x.
*
* If the LSB of @x is set, the result is 0.
* If only the MSB of @x is set, then the result is BITS_PER_LONG-1.
* If @x is 0 then the result is COUNT_TRAILING_ZEROS_0.
*/
static inline int count_trailing_zeros(unsigned long x)
{
#define COUNT_TRAILING_ZEROS_0 (-1)

if (sizeof(x) == 4)
  return ffs(x);
else
  return (x != 0) ? __ffs(x) : COUNT_TRAILING_ZEROS_0;
}

#endif /* _LINUX_BITOPS_COUNT_ZEROS_H_ */

quality91%

¤ Dauer der Verarbeitung: 0.11 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.