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Commit cfac1d08 authored by Rasmus Villemoes's avatar Rasmus Villemoes Committed by Linus Torvalds
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lib: bitmap: yet another simplification in __bitmap_shift_right 



If left is 0, we can just let mask be ~0UL, so that anding with it is a
no-op.  Conveniently, BITMAP_LAST_WORD_MASK provides precisely what we
need, and we can eliminate left.

Signed-off-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 97fb8e94

lib/bitmap.c

+4 −4
Original line number Original line Diff line number Diff line
@@ -113,9 +113,9 @@ EXPORT_SYMBOL(__bitmap_complement); 
void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,

void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,

			unsigned shift, unsigned nbits)

			unsigned shift, unsigned nbits)

{

{

	unsigned k, lim = BITS_TO_LONGS(nbits), left = nbits % BITS_PER_LONG;

	unsigned k, lim = BITS_TO_LONGS(nbits);

	unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;

	unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;

	unsigned long mask = (1UL << left) - 1;

	unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);

	for (k = 0; off + k < lim; ++k) {

	for (k = 0; off + k < lim; ++k) {

		unsigned long upper, lower;

		unsigned long upper, lower;
@@ -127,12 +127,12 @@ void __bitmap_shift_right(unsigned long *dst, const unsigned long *src, 
			upper = 0;

			upper = 0;

		else {

		else {

			upper = src[off + k + 1];

			upper = src[off + k + 1];

			if (off + k + 1 == lim - 1 && left)

			if (off + k + 1 == lim - 1)

				upper &= mask;

				upper &= mask;

			upper <<= (BITS_PER_LONG - rem);

			upper <<= (BITS_PER_LONG - rem);

		}

		}

		lower = src[off + k];

		lower = src[off + k];

		if (left && off + k == lim - 1)

		if (off + k == lim - 1)

			lower &= mask;

			lower &= mask;

		lower >>= rem;

		lower >>= rem;

		dst[k] = lower | upper;

		dst[k] = lower | upper;