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https://github.com/logos-storage/logos-storage-nim.git
synced 2026-01-15 03:43:11 +00:00
27 lines
541 B
Nim
27 lines
541 B
Nim
func extractLowBits*[n: static int](A: BigInt[n], k: int): uint64 =
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assert(k > 0 and k <= 64)
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var r: uint64 = 0
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for i in 0..<k:
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# A is big-endian. Run index backwards: n-1-i
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#let b = bit[n](A, n-1-i)
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let b = bit[n](A, i)
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let y = uint64(b)
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if (y != 0):
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r = bitor(r, 1'u64 shl i)
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return r
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func floorLog2* (x : int) : int =
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var k = -1
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var y = x
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while (y > 0):
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k += 1
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y = y shr 1
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return k
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func ceilingLog2* (x : int) : int =
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if (x==0):
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return -1
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else:
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return (floorLog2(x-1) + 1)
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