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lib/find: introduce find_nth_and_andnot_bit 

In the following patches the function is used to implement in-place bitmaps
traversing without storing intermediate result in temporary bitmaps.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Acked-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Peter Lafreniere <peter@n8pjl.ca>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Yury Norov 2023-01-20 20:24:28 -08:00 committed by Jakub Kicinski
parent 383d9f87a0
commit 4324511780
2 changed files with 42 additions and 0 deletions
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33
include/linux/find.h
View File

@ -22,6 +22,9 @@ unsigned long __find_nth_and_bit(const unsigned long *addr1, const unsigned long
unsigned long size, unsigned long n);
unsigned long __find_nth_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
unsigned long size, unsigned long n);
unsigned long __find_nth_and_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
const unsigned long *addr3, unsigned long size,
unsigned long n);
extern unsigned long _find_first_and_bit(const unsigned long *addr1,
const unsigned long *addr2, unsigned long size);
extern unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size);
@ -255,6 +258,36 @@ unsigned long find_nth_andnot_bit(const unsigned long *addr1, const unsigned lon
return __find_nth_andnot_bit(addr1, addr2, size, n);
}
/**
* find_nth_and_andnot_bit - find N'th set bit in 2 memory regions,
* excluding those set in 3rd region
* @addr1: The 1st address to start the search at
* @addr2: The 2nd address to start the search at
* @addr3: The 3rd address to start the search at
* @size: The maximum number of bits to search
* @n: The number of set bit, which position is needed, counting from 0
*
* Returns the bit number of the N'th set bit.
* If no such, returns @size.
*/
static __always_inline
unsigned long find_nth_and_andnot_bit(const unsigned long *addr1,
const unsigned long *addr2,
const unsigned long *addr3,
unsigned long size, unsigned long n)
{
if (n >= size)
return size;
if (small_const_nbits(size)) {
unsigned long val = *addr1 & *addr2 & (~*addr3) & GENMASK(size - 1, 0);
return val ? fns(val, n) : size;
}
return __find_nth_and_andnot_bit(addr1, addr2, addr3, size, n);
}
#ifndef find_first_and_bit
/**
* find_first_and_bit - find the first set bit in both memory regions

9
lib/find_bit.c
View File

@ -155,6 +155,15 @@ unsigned long __find_nth_andnot_bit(const unsigned long *addr1, const unsigned l
}
EXPORT_SYMBOL(__find_nth_andnot_bit);
unsigned long __find_nth_and_andnot_bit(const unsigned long *addr1,
const unsigned long *addr2,
const unsigned long *addr3,
unsigned long size, unsigned long n)
{
return FIND_NTH_BIT(addr1[idx] & addr2[idx] & ~addr3[idx], size, n);
}
EXPORT_SYMBOL(__find_nth_and_andnot_bit);
#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)