diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/bitmap.h | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index b0395e4ccf90..9c0d1de44350 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -57,6 +57,7 @@ struct device; * bitmap_weight(src, nbits) Hamming Weight: number set bits * bitmap_weight_and(src1, src2, nbits) Hamming Weight of and'ed bitmap * bitmap_weight_andnot(src1, src2, nbits) Hamming Weight of andnot'ed bitmap + * bitmap_weight_from(src, start, end) Hamming Weight starting from @start * bitmap_set(dst, pos, nbits) Set specified bit area * bitmap_clear(dst, pos, nbits) Clear specified bit area * bitmap_find_next_zero_area(buf, len, pos, n, mask) Find bit free area @@ -479,6 +480,38 @@ unsigned long bitmap_weight_andnot(const unsigned long *src1, return __bitmap_weight_andnot(src1, src2, nbits); } +/** + * bitmap_weight_from - Hamming weight for a memory region + * @bitmap: The base address + * @start: The bitnumber to starts weighting + * @end: the bitmap size in bits + * + * Returns the number of set bits in the region. If @start >= @end, + * return >= end. + */ +static __always_inline +unsigned long bitmap_weight_from(const unsigned long *bitmap, + unsigned int start, unsigned int end) +{ + unsigned long w; + + if (unlikely(start >= end)) + return end; + + if (small_const_nbits(end)) + return hweight_long(*bitmap & GENMASK(end - 1, start)); + + bitmap += start / BITS_PER_LONG; + /* Opencode round_down() to not include math.h */ + end -= start & ~(BITS_PER_LONG - 1); + start %= BITS_PER_LONG; + w = bitmap_weight(bitmap, end); + if (start) + w -= hweight_long(*bitmap & BITMAP_LAST_WORD_MASK(start)); + + return w; +} + static __always_inline void bitmap_set(unsigned long *map, unsigned int start, unsigned int nbits) { |