forked from Mirrors/opensbi
sbi: Introduce sbi_hartmask_weight
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>
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@@ -125,14 +125,22 @@ static inline unsigned long sbi_fls(unsigned long word)
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*/
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static inline unsigned long sbi_popcount(unsigned long word)
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{
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unsigned long count = 0;
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unsigned long count;
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while (word) {
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word &= word - 1;
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count++;
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}
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return count;
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#if BITS_PER_LONG == 64
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count = word - ((word >> 1) & 0x5555555555555555ul);
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count = (count & 0x3333333333333333ul) + ((count >> 2) & 0x3333333333333333ul);
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count = (count + (count >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
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count = count + (count >> 8);
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count = count + (count >> 16);
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return (count + (count >> 32)) & 0x00000000000000FFul;
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#else
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count = word - ((word >> 1) & 0x55555555);
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count = (count & 0x33333333) + ((count >> 2) & 0x33333333);
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count = (count + (count >> 4)) & 0x0F0F0F0F;
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count = count + (count >> 8);
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return (count + (count >> 16)) & 0x000000FF;
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#endif
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}
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#define for_each_set_bit(bit, addr, size) \
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