Sort-of working 8-bit ASCII RTTY

LICENSE

Copyright (c) 2014, Ricky Elrod

All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.

    * Redistributions in binary form must reproduce the above
      copyright notice, this list of conditions and the following
      disclaimer in the documentation and/or other materials provided
      with the distribution.

    * Neither the name of Ricky Elrod nor the names of other
      contributors may be used to endorse or promote products derived
      from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

RTTY.cabal

-- Initial RTTY.cabal generated by cabal init.  For further documentation, 
-- see http://haskell.org/cabal/users-guide/

name:                RTTY
version:             0.1.0.0
-- synopsis:            
-- description:         
license:             BSD3
license-file:        LICENSE
author:              Ricky Elrod
maintainer:          ricky@elrod.me
-- copyright:           
category:            Data
build-type:          Simple
-- extra-source-files:  
cabal-version:       >=1.10

executable RTTY
  main-is:             RTTY.hs
  -- other-modules:       
  other-extensions:    OverloadedStrings
  build-depends:       base >=4.5 && <4.7, text >=0.11 && <0.12, WAVE, text-format
  -- hs-source-dirs:      
  default-language:    Haskell2010

RTTY.hs

{-# LANGUAGE OverloadedStrings #-}
module Data.RTTY where

import Control.Monad (join)
import Data.WAVE
import Data.Int (Int32)
import Data.Char
import Data.Text.Format (left)
import Data.Text.Lazy.Builder (toLazyText)
import Data.Text.Lazy (unpack)
import Numeric (showIntAtBase)

samplesPS = 16000
bitrate = 32

header = WAVEHeader 1 samplesPS bitrate Nothing

sound :: Double  -- | Frequency
      -> Int -- | Samples per second
      -> Double -- | Lenght of sound in seconds
      -> Int32 -- | Volume, (maxBound :: Int32) for highest, 0 for lowest
      -> [Int32]
sound freq samples len volume = take (round $ len * (fromIntegral samples)) $
                         map (round . (* fromIntegral volume)) $
                         map sin [0.0, (freq * 2 * pi / (fromIntegral samples))..]

seconds = 0.0220022
zero_tone = 700
one_tone = 870

waveData = WAVE header $ rttyData "HelloWorldHelloWorldHelloWorld"

makeWavFile :: WAVE -> IO ()
makeWavFile = putWAVEFile "temp.wav"

main = makeWavFile waveData

asciiToBinary :: Char -> String
asciiToBinary c = "0" ++ reverse (unpack (toLazyText s)) ++ "11"
 where
   s = left 8 '0' (showIntAtBase 2 intToDigit (Data.Char.ord c) [])

stringToBinary :: String -> String
stringToBinary = join . map asciiToBinary

rttyData :: String -> [[Int32]]
rttyData s = map (:[]) (concat (map tone (stringToBinary s)))
 where
  tone '0' = sound zero_tone samplesPS seconds (maxBound `div` 2)
  tone '1' = sound one_tone samplesPS seconds (maxBound `div` 2)
  tone _   = error "nope!"

Setup.hs

import Distribution.Simple
main = defaultMain