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sbi: Introduce sbi_hartmask_weight

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Provide a function to count the number of set bits in a hartmask,
which builds on a new function for the same that operates on a
bitmask. While at it, improve the performance of sbi_popcount()
which is used in the implementation.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20250314163021.154530-5-ajones@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Andrew Jones
2025-03-14 17:30:23 +01:00
committed by Anup Patel
parent 2142618f12
commit a6e5f8878c
3 changed files with 39 additions and 7 deletions
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22
include/sbi/sbi_bitops.h
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@@ -125,14 +125,22 @@ static inline unsigned long sbi_fls(unsigned long word)
*/
static inline unsigned long sbi_popcount(unsigned long word)
{
unsigned long count = 0;
unsigned long count;
while (word) {
word &= word - 1;
count++;
}
return count;
#if BITS_PER_LONG == 64
count = word - ((word >> 1) & 0x5555555555555555ul);
count = (count & 0x3333333333333333ul) + ((count >> 2) & 0x3333333333333333ul);
count = (count + (count >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
count = count + (count >> 8);
count = count + (count >> 16);
return (count + (count >> 32)) & 0x00000000000000FFul;
#else
count = word - ((word >> 1) & 0x55555555);
count = (count & 0x33333333) + ((count >> 2) & 0x33333333);
count = (count + (count >> 4)) & 0x0F0F0F0F;
count = count + (count >> 8);
return (count + (count >> 16)) & 0x000000FF;
#endif
}
#define for_each_set_bit(bit, addr, size) \