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Prevent against div by zero. Make it possible to recover from ratio increases. Try to prevent large increases that are caused by timing resolution problems

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Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@3397
This commit is contained in:
Peter Veenstra 2009-05-20 18:07:06 +00:00
parent 5d8736e78f
commit acada1af49
1 changed files with 6 additions and 1 deletions
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7
src/dosbox.cpp
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@ -16,7 +16,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
/* $Id: dosbox.cpp,v 1.148 2009-04-26 15:37:04 c2woody Exp $ */
/* $Id: dosbox.cpp,v 1.149 2009-05-20 18:07:06 qbix79 Exp $ */
#include <stdlib.h>
#include <stdarg.h>
@ -168,6 +168,7 @@ increaseticks:
ticksAdded = ticksRemain;
if (CPU_CycleAutoAdjust && !CPU_SkipCycleAutoAdjust) {
if (ticksScheduled >= 250 || ticksDone >= 250 || (ticksAdded > 15 && ticksScheduled >= 5) ) {
if(ticksDone < 1) ticksDone = 1; // Protect against div by zero
/* ratio we are aiming for is around 90% usage*/
Bit32s ratio = (ticksScheduled * (CPU_CyclePercUsed*90*1024/100/100)) / ticksDone;
Bit32s new_cmax = CPU_CycleMax;
@ -178,6 +179,10 @@ increaseticks:
double ratioremoved = (double) CPU_IODelayRemoved / (double) cproc;
if (ratioremoved < 1.0) {
ratio = (Bit32s)((double)ratio * (1 - ratioremoved));
/* Don't allow very high ratio which can cause us to lock as we don't scale down
* for very low ratios. High ratio might result because of timing resolution */
if (ticksScheduled >= 250 && ticksDone < 10 && ratio > 20480)
ratio = 20480;
Bit64s cmax_scaled = (Bit64s)CPU_CycleMax * (Bit64s)ratio;
if (ratio <= 1024)
new_cmax = (Bit32s)(cmax_scaled / (Bit64s)1024);