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include: sbi_bitmap: add bitmap_empty() function

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Add bitmap_empty() to check if bitmap has no bits set.

Unlike bitmap_weight() which calls sbi_popcount() on every word,
bitmap_empty() uses simple non-zero comparisons with early exit.

Signed-off-by: Yu-Chien Peter Lin <peter.lin@sifive.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20260311125116.1401002-1-peter.lin@sifive.com
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Yu-Chien Peter Lin
2026-03-11 20:51:15 +08:00
committed by Anup Patel
parent 0b041e58c0
commit ff7d245b86
1 changed files with 16 additions and 0 deletions
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16
include/sbi/sbi_bitmap.h
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@@ -143,4 +143,20 @@ static inline int bitmap_weight(const unsigned long *src, int nbits)
return res; return res;
} }
static inline bool bitmap_empty(const unsigned long *src, int nbits)
{
if (nbits == 0)
return true;
if (small_const_nbits(nbits))
return !(*src & BITMAP_LAST_WORD_MASK(nbits));
else {
size_t i, len = BITS_TO_LONGS(nbits);
for (i = 0; i < len - 1; i++)
if (src[i])
return false;
return !(src[len - 1] & BITMAP_LAST_WORD_MASK(nbits));
}
}
#endif #endif