keep track of time

2 files changed, 11 insertions, 4 deletions

diff --git a/axis-of-eval.cabal b/axis-of-eval.cabal
index 2a90fa5..4311a85 100644
--- a/axis-of-eval.cabal
+++ b/axis-of-eval.cabal
@@ -26,6 +26,6 @@ executable midi-dump
   default-language: Haskell2010
   hs-source-dirs: .
   build-depends:
-    base, time, containers, haskore, alsa-seq, alsa-core, mtl
+    base, time, containers, haskore, alsa-seq, alsa-core, mtl, clock
   main-is: midi-dump.hs
   other-modules: AlsaSeq
diff --git a/midi-dump.hs b/midi-dump.hs
index 7d6d238..b345531 100644
--- a/midi-dump.hs
+++ b/midi-dump.hs
@@ -7,6 +7,7 @@ import qualified Sound.ALSA.Sequencer.Event as Event
 import Control.Monad.RWS.Strict
 import Data.Maybe
 import Data.List
+import System.Clock
 
 main = main' `AlsaExc.catch` handler
   where
@@ -14,7 +15,8 @@ main = main' `AlsaExc.catch` handler
 
 data LoopState = LoopState {
   keysDown :: MidiPitchSet,
-  inputHistory :: [Maybe Event.T]
+  inputHistory :: [Maybe Event.T],
+  lastTick :: TimeSpec
 }
 
 emptyLoopState = LoopState Set.empty []
@@ -23,12 +25,14 @@ main' = withAlsaInit $ \h public private q publicAddr privateAddr -> do
   cmdlineAlsaConnect h public
 
   putStrLn "Rock on!"
+  startTime <- getTime Monotonic
 
-  (_, ()) <- execRWST loop (h, public, private, q, publicAddr, privateAddr) emptyLoopState
+  (_, ()) <- execRWST loop (startTime, h, public, private, q, publicAddr, privateAddr) (emptyLoopState startTime)
   return ()
 
 loop = do
-  (h, _, _, q, publicAddr, _) <- ask
+  (startTime, h, _, _, q, publicAddr, _) <- ask
+
   oldKeys <- gets keysDown
   let forwardNOW = forwardNoteEvent h q publicAddr
   (events, newKeys) <- liftIO $ parseAlsaEvents' h oldKeys forwardNOW
@@ -36,6 +40,8 @@ loop = do
   if (oldKeys == newKeys) then
     liftIO $ threadDelay 15000 -- 15ms.  Seems like a lot, but it sounds OK.  Cuts CPU down to 2%.
   else do
+    now <- liftIO $ getTime Monotonic
+    let delta = now - startTime
     let newEvents = map Just events
 
     liftIO $ printChordLn newKeys
@@ -46,4 +52,5 @@ loop = do
       liftIO $ print hist
       modify $ \s -> s { inputHistory = Nothing:inputHistory s }
 
+    modify $ \s -> s { lastTick = now }
   loop