Bits.hs

module Module.Capnp.Bits (bitsTests) where

import Capnp.Bits
import Data.Bits
import Data.Foldable (traverse_)
import Data.Word
import Test.Hspec

bitsTests :: Spec
bitsTests = do
  describe "bitRange" bitRangeExamples
  describe "replaceBits" replaceBitsExamples

bitRangeExamples :: Spec
bitRangeExamples = do
  it "Should get single bits correctly" $
    traverse_ bitRangeTest ones
  it "Should work on this extra example" $
    bitRangeTest
      (0x0000000200000000, 32, 48, 2)
  where
    bitRangeTest :: (Word64, Int, Int, Word64) -> IO ()
    bitRangeTest (word, lo, hi, expected) =
      bitRange word lo hi `shouldBe` expected
    ones = map (\bit -> (1 `shiftL` bit, bit, bit + 1, 1)) [0 .. 63]

replaceBitsExamples :: Spec
replaceBitsExamples =
  it "Should work with several examples" $
    sequence_
      [ replaceTest (0xf :: Word8) 0 0 0xf,
        replaceTest (0x1 :: Word8) 0xf 0 0x1,
        replaceTest (0x2 :: Word8) 0x1 0 0x2,
        replaceTest (0x1 :: Word8) 0xf 0 0x1,
        replaceTest (0x2 :: Word8) 0x10 4 0x20,
        replaceTest (0x1 :: Word8) 0x10 8 0x0110,
        replaceTest (0xa :: Word8) 0xffff 8 0x0aff,
        replaceTest (0x0 :: Word1) 0xff 4 0xef
      ]
  where
    replaceTest ::
      (Bounded a, Integral a, Show a) =>
      a ->
      Word64 ->
      Int ->
      Word64 ->
      Expectation
    replaceTest new orig shift expected =
      replaceBits new orig shift `shouldBe` expected