[aandrejevic] 60816: [NTVDM] Revert a previous incorrect fix for the PIT. Modify the PitDecrementCount function to take a parameter instead of it being called multiple times (which is slower).
1 Nov
2013
1 Nov
'13
1:57 a.m.
Author: aandrejevic
Date: Fri Nov 1 01:57:40 2013
New Revision: 60816
URL: http://svn.reactos.org/svn/reactos?rev=60816&view=rev
Log:
[NTVDM]
Revert a previous incorrect fix for the PIT.
Modify the PitDecrementCount function to take a parameter instead
of it being called multiple times (which is slower).
Modified:
branches/ntvdm/subsystems/ntvdm/ntvdm.c
branches/ntvdm/subsystems/ntvdm/timer.c
branches/ntvdm/subsystems/ntvdm/timer.h
Modified: branches/ntvdm/subsystems/ntvdm/ntvdm.c
URL:
http://svn.reactos.org/svn/reactos/branches/ntvdm/subsystems/ntvdm/ntvdm.c?…
==============================================================================
--- branches/ntvdm/subsystems/ntvdm/ntvdm.c [iso-8859-1] (original)
+++ branches/ntvdm/subsystems/ntvdm/ntvdm.c [iso-8859-1] Fri Nov 1 01:57:40 2013
@@ -140,35 +140,20 @@
/* Main loop */
while (VdmRunning)
{
- /* Get the resolution of the system timer */
- DWORD TimerResolution = PitGetResolution();
-
/* Get the current number of ticks */
CurrentTickCount = GetTickCount();
- if (TimerResolution > 1000)
- {
- /* Get the current performance counter value */
- QueryPerformanceCounter(&Counter);
+ /* Get the current performance counter value */
+ QueryPerformanceCounter(&Counter);
- /* Get the number of PIT ticks that have passed */
- TimerTicks = ((Counter.QuadPart - LastTimerTick.QuadPart)
- * PIT_BASE_FREQUENCY) / Frequency.QuadPart;
- }
- else
- {
- /* Use the standard tick count */
- Counter.QuadPart = CurrentTickCount;
+ /* Get the number of PIT ticks that have passed */
+ TimerTicks = ((Counter.QuadPart - LastTimerTick.QuadPart)
+ * PIT_BASE_FREQUENCY) / Frequency.QuadPart;
- /* Get the number of PIT ticks that have passed */
- TimerTicks = ((Counter.QuadPart - LastTimerTick.QuadPart)
- * PIT_BASE_FREQUENCY) / 1000;
- }
-
/* Update the PIT */
if (TimerTicks > 0)
{
- for (i = 0; i < TimerTicks; i++) PitDecrementCount();
+ PitDecrementCount(TimerTicks);
LastTimerTick = Counter;
}
Modified: branches/ntvdm/subsystems/ntvdm/timer.c
URL:
http://svn.reactos.org/svn/reactos/branches/ntvdm/subsystems/ntvdm/timer.c?…
==============================================================================
--- branches/ntvdm/subsystems/ntvdm/timer.c [iso-8859-1] (original)
+++ branches/ntvdm/subsystems/ntvdm/timer.c [iso-8859-1] Fri Nov 1 01:57:40 2013
@@ -146,7 +146,7 @@
}
}
-VOID PitDecrementCount()
+VOID PitDecrementCount(DWORD Count)
{
INT i;
@@ -157,7 +157,12 @@
case PIT_MODE_INT_ON_TERMINAL_COUNT:
{
/* Decrement the value */
- PitChannels[i].CurrentValue--;
+ if (Count > PitChannels[i].CurrentValue)
+ {
+ /* The value does not reload in this case */
+ PitChannels[i].CurrentValue = 0;
+ }
+ else PitChannels[i].CurrentValue -= Count;
/* Did it fall to the terminal count? */
if (PitChannels[i].CurrentValue == 0 && !PitChannels[i].Pulsed)
@@ -171,47 +176,100 @@
case PIT_MODE_RATE_GENERATOR:
{
- /* Decrement the value */
- PitChannels[i].CurrentValue--;
-
- /* Did it fall to zero? */
- if (PitChannels[i].CurrentValue != 0) break;
-
- /* Yes, raise the output line and reload */
- if (i == 0) PicInterruptRequest(0);
- PitChannels[i].CurrentValue = PitChannels[i].ReloadValue;
+ BOOLEAN Reloaded = FALSE;
+
+ while (Count)
+ {
+ if ((Count > PitChannels[i].CurrentValue)
+ && (PitChannels[i].CurrentValue != 0))
+ {
+ /* Decrease the count */
+ Count -= PitChannels[i].CurrentValue;
+
+ /* Reload the value */
+ PitChannels[i].CurrentValue = PitChannels[i].ReloadValue;
+
+ /* Set the flag */
+ Reloaded = TRUE;
+ }
+ else
+ {
+ /* Decrease the value */
+ PitChannels[i].CurrentValue -= Count;
+
+ /* Clear the count */
+ Count = 0;
+
+ /* Did it fall to zero? */
+ if (PitChannels[i].CurrentValue == 0)
+ {
+ PitChannels[i].CurrentValue = PitChannels[i].ReloadValue;
+ Reloaded = TRUE;
+ }
+ }
+ }
+
+ /* If there was a reload on channel 0, raise IRQ 0 */
+ if ((i == 0) && Reloaded) PicInterruptRequest(0);
break;
}
case PIT_MODE_SQUARE_WAVE:
{
- /* Decrement the value by 2 */
- PitChannels[i].CurrentValue -= 2;
-
- /* Did it fall to zero? */
- if (PitChannels[i].CurrentValue != 0) break;
-
- /* Yes, toggle the flip-flop */
- PitChannels[i].OutputFlipFlop = !PitChannels[i].OutputFlipFlop;
-
- /* Did this create a rising edge in the signal? */
- if (PitChannels[i].OutputFlipFlop)
- {
- /* Yes, IRQ 0 if this is channel 0 */
- if (i == 0) PicInterruptRequest(0);
- }
-
- /* Reload the value, but make sure it's even */
- if (PitChannels[i].ReloadValue % 2)
- {
- /* It's odd, reduce it by 1 */
- PitChannels[i].CurrentValue = PitChannels[i].ReloadValue - 1;
- }
- else
- {
- /* It was even */
- PitChannels[i].CurrentValue = PitChannels[i].ReloadValue;
+ INT ReloadCount = 0;
+ WORD ReloadValue = PitChannels[i].ReloadValue;
+
+ /* The reload value must be even */
+ ReloadValue &= ~1;
+
+ while (Count)
+ {
+ if (((Count * 2) > PitChannels[i].CurrentValue)
+ && (PitChannels[i].CurrentValue != 0))
+ {
+ /* Decrease the count */
+ Count -= PitChannels[i].CurrentValue / 2;
+
+ /* Reload the value */
+ PitChannels[i].CurrentValue = ReloadValue;
+
+ /* Increment the reload count */
+ ReloadCount++;
+ }
+ else
+ {
+ /* Clear the count */
+ Count = 0;
+
+ /* Decrease the value */
+ PitChannels[i].CurrentValue -= Count * 2;
+
+ /* Did it fall to zero? */
+ if (PitChannels[i].CurrentValue == 0)
+ {
+ /* Reload the value */
+ PitChannels[i].CurrentValue = ReloadValue;
+
+ /* Increment the reload count */
+ ReloadCount++;
+ }
+ }
+ }
+
+ if (ReloadCount == 0) break;
+
+ /* Toggle the flip-flop if the number of reloads was odd */
+ if (ReloadCount & 1)
+ {
+ PitChannels[i].OutputFlipFlop = !PitChannels[i].OutputFlipFlop;
+ }
+
+ /* Was there any rising edge on channel 0 ? */
+ if ((PitChannels[i].OutputFlipFlop || ReloadCount) && (i == 0))
+ {
+ /* Yes, IRQ 0 */
+ PicInterruptRequest(0);
}
break;
Modified: branches/ntvdm/subsystems/ntvdm/timer.h
URL:
http://svn.reactos.org/svn/reactos/branches/ntvdm/subsystems/ntvdm/timer.h?…
==============================================================================
--- branches/ntvdm/subsystems/ntvdm/timer.h [iso-8859-1] (original)
+++ branches/ntvdm/subsystems/ntvdm/timer.h [iso-8859-1] Fri Nov 1 01:57:40 2013
@@ -48,7 +48,7 @@
VOID PitWriteCommand(BYTE Value);
BYTE PitReadData(BYTE Channel);
VOID PitWriteData(BYTE Channel, BYTE Value);
-VOID PitDecrementCount();
+VOID PitDecrementCount(DWORD Count);
DWORD PitGetResolution(VOID);
#endif // _TIMER_H_
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