Language/Atom/Example.hs

-- | An example atom design.
module Language.Atom.Example
 ( compileExample
 , example
 ) where

import Language.Atom

-- | Invoke the atom compiler.
compileExample :: IO ()
compileExample = do
 (schedule, _, _, _, _) <- compile "example" defaults { cCode = prePostCode } example
 putStrLn $ reportSchedule schedule

prePostCode :: [Name] -> [Name] -> [(Name, Type)] -> (String, String)
prePostCode _ _ _ =
 ( unlines
 [ "#include <stdlib.h>"
 , "#include <stdio.h>"
 , "unsigned long int a;"
 , "unsigned long int b;"
 , "unsigned long int x;"
 , "unsigned char running = 1;"
 ]
 , unlines
 [ "int main(int argc, char* argv[]) {"
 , " if (argc < 3) {"
 , " printf(\"usage: gcd <num1> <num2>\\n\");"
 , " }"
 , " else {"
 , " a = atoi(argv[1]);"
 , " b = atoi(argv[2]);"
 , " printf(\"Computing the GCD of %lu and %lu...\\n\", a, b);"
 , " while(running) {"
 , " example();"
 , " printf(\"iteration: a = %lu b = %lu\\n\", a, b);"
 , " }"
 , " printf(\"GCD result: %lu\\n\", a);"
 , " }"
 , " return 0;"
 , "}"
 ]
 )

-- | An example design that computes the greatest common divisor.
example :: Atom ()
example = do

 -- External reference to value A.
 let a = word32' "a"

 -- External reference to value B.
 let b = word32' "b"

 -- The external running flag.
 let running = bool' "running"

 -- A rule to modify A.
 atom "a_minus_b" $ do
 cond $ value a >. value b
 a <== value a - value b

 -- A rule to modify B.
 atom "b_minus_a" $ do
 cond $ value b >. value a
 b <== value b - value a

 -- A rule to clear the running flag.
 atom "stop" $ do
 cond $ value a ==. value b
 running <== false