bug in timing code

[Erik Auerswald]

Hi,

there is a bug in engine/schedule.c, function rate_limit(): The
transformation from delay in units of 10ms to gameframes is not correct.
The same wrong formula is used in engine/sprite.c, function
sprite_alarm(). The correct formula is delay*10/time_for_one_frame.

Using the name FRAMERATE for the time of one frame is a litte bit
confusing, I suggest using the name FRAMETIME.

The attached patch corrects these errors and renames FRAMERATE to
FRAMETIME. I did not apply it to svn because all timing values in the
code are tailored to this incorrect behaviour, therefore the delay
values need to be multiplied by 9 to keep the current timing. I did not
(yet) search for all the places where delays are specified...

Erik
-------------- next part --------------
diff -uNrB airstrike/src/core/display.c airstrike-timing/src/core/display.c
--- airstrike/src/core/display.c	2005-08-31 10:26:46.021276848 +0200
+++ airstrike-timing/src/core/display.c	2005-08-31 10:41:42.785113642 +0200
@@ -5,7 +5,7 @@
 
 struct display display = 
   {
-    .frame_time = FRAMERATE,
+    .frame_time = FRAMETIME,
     .use_alpha = 1
   };
 
diff -uNrB airstrike/src/core/display.h airstrike-timing/src/core/display.h
--- airstrike/src/core/display.h	2005-08-31 10:26:46.121251471 +0200
+++ airstrike-timing/src/core/display.h	2005-08-31 10:41:42.796110841 +0200
@@ -4,7 +4,7 @@
 #include <SDL.h>
 #include "image.h"
 
-#define FRAMERATE 30
+#define FRAMETIME 30
 #define DIRTY_TILE_SIZE 64
 
 extern struct display
diff -uNrB airstrike/src/engine/schedule.c airstrike-timing/src/engine/schedule.c
--- airstrike/src/engine/schedule.c	2005-08-31 10:26:44.666620716 +0200
+++ airstrike-timing/src/engine/schedule.c	2005-08-31 10:42:31.240771642 +0200
@@ -94,7 +94,7 @@
   if (now >= *timer)
     {
       /* convert milliseconds to frames */
-      *timer = now + delay * FRAMERATE / 10;
+      *timer = now + (delay * 10) / FRAMETIME;
       return 1;
     }
   else
diff -uNrB airstrike/src/engine/sprite.c airstrike-timing/src/engine/sprite.c
--- airstrike/src/engine/sprite.c	2005-08-31 10:26:43.423936160 +0200
+++ airstrike-timing/src/engine/sprite.c	2005-08-31 10:43:01.355101264 +0200
@@ -63,7 +63,7 @@
 
 void sprite_alarm(unsigned int delay, sprite_t *target, msg_t msg)
 {
-  schedule(delay*FRAMERATE/10,SCHED_NORMAL,send_alarm,msg,target);
+  schedule((delay*10)/FRAMETIME,SCHED_NORMAL,send_alarm,msg,target);
 }
 
 /* Frame checklist
diff -uNrB airstrike/src/tests/testengine.c airstrike-timing/src/tests/testengine.c
--- airstrike/src/tests/testengine.c	2005-08-31 10:26:41.786351845 +0200
+++ airstrike-timing/src/tests/testengine.c	2005-08-31 10:41:43.974810619 +0200
@@ -58,7 +58,7 @@
   if (reason) {
     ui_message(reason,400,300,ALIGN_CENTER,big_font,20); 
   }
-  for (idx = 0; idx < 2*FRAMERATE; idx++) {
+  for (idx = 0; idx < 2*FRAMETIME; idx++) {
     /* update screen while waiting */
     draw_frame();
     game_frame();