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Joey Yakimowich-Payne 2020-02-13 06:28:16 -07:00
commit b3dad3007c
2 changed files with 11 additions and 9 deletions
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lib/pure/bitops.nim
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@ -355,6 +355,15 @@ proc firstSetBit*(x: SomeInteger): int {.inline, noSideEffect.} =
when sizeof(x) <= 4: result = firstSetBitNim(x.uint32)
else: result = firstSetBitNim(x.uint64)
proc lastSetBit*(x: SomeUnsignedInt): uint {.inline, noSideEffect.} =
## Returns the 1-based index of the most significant set bit of x.
## If x == 0, the result will also be 0
var temp = x
result = 0
while temp != 0:
temp = temp shr 1
result += 1
proc fastLog2*(x: SomeInteger): int {.inline, noSideEffect.} =
## Quickly find the log base 2 of an integer.
## If `x` is zero, when ``noUndefinedBitOpts`` is set, result is -1,