Add constant-time Uint::shr() and Uint::shl()
#267
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fjarri
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tarcieri
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Aug 28, 2023
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This overrides the
shr()implementation in #263 - this one is more efficient (O(LIMBS * log2(BITS)) instead of O(LIMBS^2)). ForU2048it's ~10x slower than the vartime equivalent.Question for @tarcieri : what behavior do we want on overflow?
shl()/shr()currently return 0, their vartime equivalents return the original value. I wonder if it would be better to return a pair(Self, CtChoice)where the second element indicates the overflow.