[Tux4kids-commits] r1193 - tuxmath/branches/lan/src

[David Bruce]

Author: dbruce-guest
Date: 2009-07-13 02:54:28 +0000 (Mon, 13 Jul 2009)
New Revision: 1193

Added:
   tuxmath/branches/lan/src/throttle.c
   tuxmath/branches/lan/src/throttle.h
Log:
added small loop-throttling function



Added: tuxmath/branches/lan/src/throttle.c
===================================================================
--- tuxmath/branches/lan/src/throttle.c	                        (rev 0)
+++ tuxmath/branches/lan/src/throttle.c	2009-07-13 02:54:28 UTC (rev 1193)
@@ -0,0 +1,41 @@
+/*
+*  C Implementation: network.c
+*
+*         Description: A simple function that uses SDL_Delay() to keep 
+*                      loops from eating all available CPU.
+
+*
+* Author: David Bruce, and the TuxMath team, (C) 2009
+* Developers list: <tuxmath-devel at lists.sourceforge.net>
+*
+* Copyright: See COPYING file that comes with this distribution.  (Briefly, GNU GPL).
+*/
+
+
+#include "SDL.h"
+
+void Throttle(int loop_msec)
+{
+  static Uint32 now_t, last_t; //These will be zero first time through
+  int wait_t;
+
+  //Target loop time must be between 0 and 100 msec:
+  if(loop_msec < 0)
+    loop_msec = 0;
+  if(loop_msec > 100)
+    loop_msec = 100;
+
+  //See if we need to wait:
+  now_t = SDL_GetTicks();
+  if (now_t < (last_t + loop_msec))
+  {
+    wait_t = (last_t + loop_msec) - now_t;
+    //Avoid problem if we somehow wrap past uint32 size (at 49.7 days!)
+    if(wait_t < 0)
+      wait_t = 0;
+    if(wait_t > loop_msec)
+      wait_t = loop_msec;
+    SDL_Delay(wait_t);
+  }
+  last_t = SDL_GetTicks();
+}

Added: tuxmath/branches/lan/src/throttle.h
===================================================================
--- tuxmath/branches/lan/src/throttle.h	                        (rev 0)
+++ tuxmath/branches/lan/src/throttle.h	2009-07-13 02:54:28 UTC (rev 1193)
@@ -0,0 +1,20 @@
+/*
+
+        throttle.h
+
+        Description: A simple function that uses SDL_Delay() to keep loops from eating all available
+                     CPU
+        Author: David Bruce and the TuxMath team, (C) 2009
+
+        Copyright: See COPYING file that comes with this distribution (briefly, GNU GPL version 2 or later)
+
+*/
+
+#ifndef THROTTLE_H
+#define THROTTLE_H
+// This simple function uses SDL_Delay() to wait to return until 'loop_msec'
+// milliseconds after it returned the last time. Per SDL docs, the granularity
+// is likely no better than 10 msec
+void Throttle(int loop_msec);
+
+#endif