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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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13
include/sbi/sbi_bitmap.h
View File

@@ -130,4 +130,17 @@ static inline void bitmap_xor(unsigned long *dst, const unsigned long *src1,
__bitmap_xor(dst, src1, src2, nbits);
}
static inline int bitmap_weight(const unsigned long *src, int nbits)
{
int i, res = 0;
for (i = 0; i < nbits / BITS_PER_LONG; i++)
res += sbi_popcount(src[i]);
if (nbits % BITS_PER_LONG)
res += sbi_popcount(src[i] & BITMAP_LAST_WORD_MASK(nbits));
return res;
}
#endif

22
include/sbi/sbi_bitops.h
View File

@@ -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) \

11
include/sbi/sbi_hartmask.h
View File

@@ -181,6 +181,17 @@ static inline void sbi_hartmask_xor(struct sbi_hartmask *dstp,
sbi_hartmask_bits(src2p), SBI_HARTMASK_MAX_BITS);
}
/**
* Count of bits in *srcp
* @param srcp the hartmask to count bits in
*
* Return: count of bits set in *srcp
*/
static inline int sbi_hartmask_weight(const struct sbi_hartmask *srcp)
{
return bitmap_weight(sbi_hartmask_bits(srcp), SBI_HARTMASK_MAX_BITS);
}
/**
* Iterate over each HART index in hartmask
* __i hart index