Created
October 9, 2022 15:39
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Generate random bit masks for corrupting packets with probability
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| {-# LANGUAGE ScopedTypeVariables #-} | |
| -- https://stackoverflow.com/questions/2075912/generate-a-random-binary-number-with-a-variable-proportion-of-1-bits | |
| import Control.Monad (replicateM) | |
| import Data.Bits | |
| import Data.Foldable (foldl') | |
| import Data.Word (Word8) | |
| import Numeric.Natural (Natural) | |
| import System.Random (Random, randomIO) | |
| generate :: forall a p. (Bits a, Random a, Ord p, Fractional p) => p -> IO a | |
| generate prob = res | |
| where | |
| tol :: (Fractional p) => p | |
| tol = 0.001 | |
| gas :: Natural | |
| gas = 10 | |
| plan :: (Fractional p, Bits a) => p -> Natural -> [a -> a -> a] | |
| plan p g | |
| | g == 0 = [] | |
| | p > 0.5 + tol = (.|.) : plan (2 * p - 1) (g - 1) | |
| | p < 0.5 - tol = (.&.) : plan (2 * p) (g - 1) | |
| | otherwise = [] | |
| res :: IO a | |
| res = do | |
| let ops = plan prob gas | |
| nOps = length ops | |
| x0 <- randomIO | |
| xs <- replicateM nOps randomIO | |
| pure $ foldr (\(x, op) acc -> op x acc) x0 (zip xs ops) |
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