Don't sleep longer than necessary to meet the interval.

[cellular-automata.git] / 003 / src / life.erl

diff --git a/003/src/life.erl b/003/src/life.erl
index 74868da..f4b1fe5 100644 (file)
--- a/003/src/life.erl
+++ b/003/src/life.erl
@@ -7,7 +7,7 @@
 -define(CHAR_ALIVE, 111).  % "o"
 -define(CHAR_BAR,    45).  % "-"
 
--define(INTERVAL, 100).
+-define(GEN_INTERVAL, 100).
 
 
 -record(state, {x            :: non_neg_integer()
@@ -61,14 +61,22 @@ life_loop(
         end
     ),
 
-    {NewTime, NewBoard} = timer:tc(fun() -> next_generation(X, Y, Board) end),
+    {NewTime, NewBoard} = timer:tc(
+        fun() ->
+            next_generation(X, Y, Board)
+        end
+    ),
+
     NewState = State#state{board        = NewBoard
                           ,gen_count    = GenCount + 1
                           ,gen_duration = NewTime
                           ,print_time   = PrintTime
     },
 
-    timer:sleep(?INTERVAL),
+    NewTimeMil = NewTime / 1000,
+    NextGenDelay = round(?GEN_INTERVAL - NewTimeMil),
+    timer:sleep(NextGenDelay),
+
     life_loop(NewState).
 
 
@@ -89,6 +97,9 @@ do_print_status(Bar, X, Y, N, GenCount, TimeMic, PrintTimeMic) ->
 
 
 do_print_board(Board) ->
+    % It seems that just doing a fold should be faster than map + to_list
+    % combo, but, after measuring several times, map + to_list has been
+    % consistently (nearly twice) faster than either foldl or foldr.
     RowStrings = array:to_list(
         array:map(
             fun(_, Row) ->