GHC.Integer.Logarithms.Internals
| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Description
Fast Integer logarithms to base 2. integerLog2# and wordLog2# are of general usefulness, the others are only needed for a fast implementation of fromRational. Since they are needed in GHC.Float, we must expose this module, but it should not show up in the docs.
See https://gitlab.haskell.org/ghc/ghc/issues/5122 for the origin of the code in this module
wordLog2# :: Word# -> Int# Source
Compute base-2 log of Word#
This is internally implemented as count-leading-zeros machine instruction.
integerLog2IsPowerOf2# :: Integer -> (# Int#, Int# #) Source
Extended version of integerLog2#
Assumption: Integer is strictly positive
First component of result is log2 n, second is 0# iff n is a power of two.
integerLog2# :: Integer -> Int# Source
Calculate the integer base 2 logarithm of an Integer. The calculation is more efficient than for the general case, on platforms with 32- or 64-bit words much more efficient.
The argument must be strictly positive, that condition is not checked.
roundingMode# :: Integer -> Int# -> Int# Source
© The University of Glasgow and others
Licensed under a BSD-style license (see top of the page).
https://downloads.haskell.org/~ghc/8.10.2/docs/html/libraries/integer-gmp-1.0.3.0/GHC-Integer-Logarithms-Internals.html