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[NTVDM]

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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).


svn path=/branches/ntvdm/; revision=60816
This commit is contained in:
Aleksandar Andrejevic 2013-11-01 01:57:40 +00:00
parent f62b9a81d4
commit 90d7fbd4a8
3 changed files with 92 additions and 49 deletions
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27
subsystems/ntvdm/ntvdm.c
View file

@ -140,35 +140,20 @@ INT wmain(INT argc, WCHAR *argv[])
/* 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;
}

112
subsystems/ntvdm/timer.c
View file

@ -146,7 +146,7 @@ VOID PitWriteData(BYTE Channel, BYTE Value)
}
}
VOID PitDecrementCount()
VOID PitDecrementCount(DWORD Count)
{
INT i;
@ -157,7 +157,12 @@ VOID PitDecrementCount()
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 @@ VOID PitDecrementCount()
case PIT_MODE_RATE_GENERATOR:
{
/* Decrement the value */
PitChannels[i].CurrentValue--;
BOOLEAN Reloaded = FALSE;
/* Did it fall to zero? */
if (PitChannels[i].CurrentValue != 0) break;
while (Count)
{
if ((Count > PitChannels[i].CurrentValue)
&& (PitChannels[i].CurrentValue != 0))
{
/* Decrease the count */
Count -= PitChannels[i].CurrentValue;
/* Yes, raise the output line and reload */
if (i == 0) PicInterruptRequest(0);
PitChannels[i].CurrentValue = PitChannels[i].ReloadValue;
/* 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;
INT ReloadCount = 0;
WORD ReloadValue = PitChannels[i].ReloadValue;
/* Did it fall to zero? */
if (PitChannels[i].CurrentValue != 0) break;
/* The reload value must be even */
ReloadValue &= ~1;
/* Yes, toggle the flip-flop */
PitChannels[i].OutputFlipFlop = !PitChannels[i].OutputFlipFlop;
/* Did this create a rising edge in the signal? */
if (PitChannels[i].OutputFlipFlop)
while (Count)
{
/* Yes, IRQ 0 if this is channel 0 */
if (i == 0) PicInterruptRequest(0);
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++;
}
}
}
/* Reload the value, but make sure it's even */
if (PitChannels[i].ReloadValue % 2)
if (ReloadCount == 0) break;
/* Toggle the flip-flop if the number of reloads was odd */
if (ReloadCount & 1)
{
/* It's odd, reduce it by 1 */
PitChannels[i].CurrentValue = PitChannels[i].ReloadValue - 1;
PitChannels[i].OutputFlipFlop = !PitChannels[i].OutputFlipFlop;
}
else
/* Was there any rising edge on channel 0 ? */
if ((PitChannels[i].OutputFlipFlop || ReloadCount) && (i == 0))
{
/* It was even */
PitChannels[i].CurrentValue = PitChannels[i].ReloadValue;
/* Yes, IRQ 0 */
PicInterruptRequest(0);
}
break;

2
subsystems/ntvdm/timer.h
View file

@ -48,7 +48,7 @@ typedef struct _PIT_CHANNEL
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_