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: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -113,9 +113,9 @@ EXPORT_SYMBOL(__bitmap_complement);
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void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
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unsigned shift, unsigned nbits)
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{
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unsigned k, lim = BITS_TO_LONGS(nbits), left = nbits % BITS_PER_LONG;
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unsigned k, lim = BITS_TO_LONGS(nbits);
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unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
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unsigned long mask = (1UL << left) - 1;
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unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
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for (k = 0; off + k < lim; ++k) {
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unsigned long upper, lower;
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@ -127,12 +127,12 @@ void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
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upper = 0;
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else {
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upper = src[off + k + 1];
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if (off + k + 1 == lim - 1 && left)
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if (off + k + 1 == lim - 1)
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upper &= mask;
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upper <<= (BITS_PER_LONG - rem);
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}
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lower = src[off + k];
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if (left && off + k == lim - 1)
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if (off + k == lim - 1)
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lower &= mask;
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lower >>= rem;
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dst[k] = lower | upper;
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