Hello, I have been mucking around with bits and hardware recently, and found the following two functions quite useful. Perhpas we should add them (or something similar) to Data.Bits? -- Manipulating bit arrays -- Warning: this actually uses lazyness :-) -- | Get an element from a bit vector. -- 0: least significant element (right-most in math notation) array .!. index = let x = fromIntegral (array `shiftR` (bitSize x * index)) in x -- | Join two sequences of bits together. -- Here we use 'fromIntegral' to simply resize bit-vectors. -- If it does something fancier, the amout we 'shiftL' may be wrong. -- As long as one sticks to the "usual" types this is not a problem. b1 `nextTo` b2 = (fromIntegral b1 `shiftL` bitSize b2) .|. fromIntegral b2 Examples:
showBin ((-1::Word16) `nextTo` (10::Word8) :: Word32) "00000000111111111111111100001010"
showBin (((-1::Word16) `nextTo` (10::Word8) :: Word32) .!. 0 :: Word16) "1111111100001010"
showBin (((-1::Word16) `nextTo` (10::Word8) :: Word32) .!. 1 :: Word8) "11111111"
Usually I don't need to specify nearly as many type annotations simply because it is obvious from the context what size quantities are needed. -Iavor