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// SPDX-License-Identifier: GPL-2.0-or-later
/* bit search implementation
*
* Copied from lib/find_bit.c to tools/lib/find_bit.c
*
* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* Copyright (C) 2008 IBM Corporation
* 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au>
* (Inspired by David Howell's find_next_bit implementation)
*
* Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
* size and improve performance, 2015.
*/
#include <linux/bitops.h>
#include <linux/bitmap.h>
#include <linux/kernel.h>
/*
* Common helper for find_bit() function family
* @FETCH: The expression that fetches and pre-processes each word of bitmap(s)
* @MUNGE: The expression that post-processes a word containing found bit (may be empty)
* @size: The bitmap size in bits
*/
#define FIND_FIRST_BIT(FETCH, MUNGE, size) \
({ \
unsigned long idx, val, sz = (size); \
\
for (idx = 0; idx * BITS_PER_LONG < sz; idx++) { \
val = (FETCH); \
if (val) { \
sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(val)), sz); \
break; \
} \
} \
\
sz; \
})
/*
* Common helper for find_next_bit() function family
* @FETCH: The expression that fetches and pre-processes each word of bitmap(s)
* @MUNGE: The expression that post-processes a word containing found bit (may be empty)
* @size: The bitmap size in bits
* @start: The bitnumber to start searching at
*/
#define FIND_NEXT_BIT(FETCH, MUNGE, size, start) \
({ \
unsigned long mask, idx, tmp, sz = (size), __start = (start); \
\
if (unlikely(__start >= sz)) \
goto out; \
\
mask = MUNGE(BITMAP_FIRST_WORD_MASK(__start)); \
idx = __start / BITS_PER_LONG; \
\
for (tmp = (FETCH) & mask; !tmp; tmp = (FETCH)) { \
if ((idx + 1) * BITS_PER_LONG >= sz) \
goto out; \
idx++; \
} \
\
sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(tmp)), sz); \
out: \
sz; \
})
#ifndef find_first_bit
/*
* Find the first set bit in a memory region.
*/
unsigned long _find_first_bit(const unsigned long *addr, unsigned long size)
{
return FIND_FIRST_BIT(addr[idx], /* nop */, size);
}
#endif
#ifndef find_first_and_bit
/*
* Find the first set bit in two memory regions.
*/
unsigned long _find_first_and_bit(const unsigned long *addr1,
const unsigned long *addr2,
unsigned long size)
{
return FIND_FIRST_BIT(addr1[idx] & addr2[idx], /* nop */, size);
}
#endif
#ifndef find_first_zero_bit
/*
* Find the first cleared bit in a memory region.
*/
unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size)
{
return FIND_FIRST_BIT(~addr[idx], /* nop */, size);
}
#endif
#ifndef find_next_bit
unsigned long _find_next_bit(const unsigned long *addr, unsigned long nbits, unsigned long start)
{
return FIND_NEXT_BIT(addr[idx], /* nop */, nbits, start);
}
#endif
#ifndef find_next_and_bit
unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2,
unsigned long nbits, unsigned long start)
{
return FIND_NEXT_BIT(addr1[idx] & addr2[idx], /* nop */, nbits, start);
}
#endif
#ifndef find_next_zero_bit
unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits,
unsigned long start)
{
return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start);
}
#endif
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