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bitmap: introduce bitmap_weighted_xor()

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The function helps to XOR bitmaps and calculate Hamming weight of
the result in one pass.

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Yury Norov <ynorov@nvidia.com>
This commit is contained in:
Yury Norov
2026-03-01 20:11:55 -05:00
parent 95d324fb1b
commit d57e74f104
2 changed files with 22 additions and 0 deletions
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15
include/linux/bitmap.h
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@@ -46,6 +46,7 @@ struct device;
* bitmap_and(dst, src1, src2, nbits) *dst = *src1 & *src2
* bitmap_or(dst, src1, src2, nbits) *dst = *src1 | *src2
* bitmap_weighted_or(dst, src1, src2, nbits) *dst = *src1 | *src2. Returns Hamming Weight of dst
* bitmap_weighted_xor(dst, src1, src2, nbits) *dst = *src1 ^ *src2. Returns Hamming Weight of dst
* bitmap_xor(dst, src1, src2, nbits) *dst = *src1 ^ *src2
* bitmap_andnot(dst, src1, src2, nbits) *dst = *src1 & ~(*src2)
* bitmap_complement(dst, src, nbits) *dst = ~(*src)
@@ -169,6 +170,8 @@ void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, unsigned int nbits);
unsigned int __bitmap_weighted_or(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, unsigned int nbits);
unsigned int __bitmap_weighted_xor(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, unsigned int nbits);
void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, unsigned int nbits);
bool __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
@@ -353,6 +356,18 @@ unsigned int bitmap_weighted_or(unsigned long *dst, const unsigned long *src1,
}
}
static __always_inline
unsigned int bitmap_weighted_xor(unsigned long *dst, const unsigned long *src1,
const unsigned long *src2, unsigned int nbits)
{
if (small_const_nbits(nbits)) {
*dst = *src1 ^ *src2;
return hweight_long(*dst & BITMAP_LAST_WORD_MASK(nbits));
} else {
return __bitmap_weighted_xor(dst, src1, src2, nbits);
}
}
static __always_inline
void bitmap_xor(unsigned long *dst, const unsigned long *src1,
const unsigned long *src2, unsigned int nbits)

7
lib/bitmap.c
View File

@@ -363,6 +363,13 @@ unsigned int __bitmap_weighted_or(unsigned long *dst, const unsigned long *bitma
}
EXPORT_SYMBOL(__bitmap_weighted_or);
unsigned int __bitmap_weighted_xor(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, unsigned int bits)
{
return BITMAP_WEIGHT(({dst[idx] = bitmap1[idx] ^ bitmap2[idx]; dst[idx]; }), bits);
}
EXPORT_SYMBOL(__bitmap_weighted_xor);
void __bitmap_set(unsigned long *map, unsigned int start, int len)
{
unsigned long *p = map + BIT_WORD(start);