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Yury Norov
be56db15fc
The 'leading' helper returns BITS_PER_LONG if x == 0, while 'trailing' one returns COUNT_TRAILING_ZEROS_0, which turns to be -1. None of the current users explicitly check the returned value for COUNT_TRAILING_ZEROS_0, except the loongarch, which tests implicitly for the '>= 0'. So, align count_trailing_zeros() with the count_leading_zeros(), and simplify the loongarch handling. Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com> Signed-off-by: Yury Norov <ynorov@nvidia.com>
47 lines
1.3 KiB
C
47 lines
1.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/* Count leading and trailing zeros functions
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*
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* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#ifndef _LINUX_BITOPS_COUNT_ZEROS_H_
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#define _LINUX_BITOPS_COUNT_ZEROS_H_
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#include <asm/bitops.h>
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/**
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* count_leading_zeros - Count the number of zeros from the MSB back
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* @x: The value
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*
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* Count the number of leading zeros from the MSB going towards the LSB in @x.
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*
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* If the MSB of @x is set, the result is 0.
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* If only the LSB of @x is set, then the result is BITS_PER_LONG-1.
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* If @x is 0 then the result is BITS_PER_LONG.
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*/
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static inline int count_leading_zeros(unsigned long x)
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{
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if (sizeof(x) == 4)
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return BITS_PER_LONG - fls(x);
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else
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return BITS_PER_LONG - fls64(x);
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}
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/**
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* count_trailing_zeros - Count the number of zeros from the LSB forwards
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* @x: The value
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*
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* Count the number of trailing zeros from the LSB going towards the MSB in @x.
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*
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* If the LSB of @x is set, the result is 0.
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* If only the MSB of @x is set, then the result is BITS_PER_LONG-1.
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* If @x is 0 then the result is BITS_PER_LONG.
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*/
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static inline int count_trailing_zeros(unsigned long x)
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{
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return x ? __ffs(x) : BITS_PER_LONG;
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}
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#endif /* _LINUX_BITOPS_COUNT_ZEROS_H_ */
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