[PATCH v2 1/4] bitmap: introduce bitmap_weighted_xor()
From: Yury Norov <hidden>
Date: 2026-03-02 01:12:09
Also in:
dri-devel, intel-wired-lan, intel-xe, lkml
Subsystem:
bitmap api, library code, the rest · Maintainers:
Yury Norov, Andrew Morton, Linus Torvalds
The function helps to XOR bitmaps and calculate Hamming weight of the result in one pass. Signed-off-by: Yury Norov <redacted> --- include/linux/bitmap.h | 15 +++++++++++++++ lib/bitmap.c | 7 +++++++ 2 files changed, 22 insertions(+)
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index b0395e4ccf90..874f744870ef 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h@@ -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)
@@ -168,6 +169,8 @@ 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,
@@ -352,6 +355,18 @@ 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)
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 9dc526507875..a2bcb5b1fe99 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c@@ -361,6 +361,13 @@ unsigned int __bitmap_weighted_or(unsigned long *dst, const unsigned long *bitma return BITMAP_WEIGHT(({dst[idx] = bitmap1[idx] | bitmap2[idx]; dst[idx]; }), bits); } +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);
--
2.43.0