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[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). svn path=/branches/ntvdm/; revision=60816
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@ -140,35 +140,20 @@ INT wmain(INT argc, WCHAR *argv[])
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/* Main loop */
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while (VdmRunning)
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{
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/* Get the resolution of the system timer */
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DWORD TimerResolution = PitGetResolution();
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/* Get the current number of ticks */
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CurrentTickCount = GetTickCount();
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if (TimerResolution > 1000)
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{
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/* Get the current performance counter value */
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QueryPerformanceCounter(&Counter);
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/* Get the number of PIT ticks that have passed */
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TimerTicks = ((Counter.QuadPart - LastTimerTick.QuadPart)
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* PIT_BASE_FREQUENCY) / Frequency.QuadPart;
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}
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else
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{
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/* Use the standard tick count */
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Counter.QuadPart = CurrentTickCount;
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/* Get the number of PIT ticks that have passed */
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TimerTicks = ((Counter.QuadPart - LastTimerTick.QuadPart)
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* PIT_BASE_FREQUENCY) / 1000;
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}
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/* Update the PIT */
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if (TimerTicks > 0)
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{
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for (i = 0; i < TimerTicks; i++) PitDecrementCount();
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PitDecrementCount(TimerTicks);
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LastTimerTick = Counter;
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}
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@ -146,7 +146,7 @@ VOID PitWriteData(BYTE Channel, BYTE Value)
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}
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}
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VOID PitDecrementCount()
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VOID PitDecrementCount(DWORD Count)
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{
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INT i;
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@ -157,7 +157,12 @@ VOID PitDecrementCount()
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case PIT_MODE_INT_ON_TERMINAL_COUNT:
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{
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/* Decrement the value */
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PitChannels[i].CurrentValue--;
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if (Count > PitChannels[i].CurrentValue)
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{
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/* The value does not reload in this case */
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PitChannels[i].CurrentValue = 0;
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}
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else PitChannels[i].CurrentValue -= Count;
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/* Did it fall to the terminal count? */
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if (PitChannels[i].CurrentValue == 0 && !PitChannels[i].Pulsed)
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@ -171,47 +176,100 @@ VOID PitDecrementCount()
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case PIT_MODE_RATE_GENERATOR:
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{
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/* Decrement the value */
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PitChannels[i].CurrentValue--;
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BOOLEAN Reloaded = FALSE;
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while (Count)
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{
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if ((Count > PitChannels[i].CurrentValue)
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&& (PitChannels[i].CurrentValue != 0))
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{
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/* Decrease the count */
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Count -= PitChannels[i].CurrentValue;
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/* Reload the value */
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PitChannels[i].CurrentValue = PitChannels[i].ReloadValue;
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/* Set the flag */
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Reloaded = TRUE;
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}
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else
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{
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/* Decrease the value */
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PitChannels[i].CurrentValue -= Count;
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/* Clear the count */
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Count = 0;
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/* Did it fall to zero? */
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if (PitChannels[i].CurrentValue != 0) break;
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/* Yes, raise the output line and reload */
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if (i == 0) PicInterruptRequest(0);
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if (PitChannels[i].CurrentValue == 0)
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{
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PitChannels[i].CurrentValue = PitChannels[i].ReloadValue;
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Reloaded = TRUE;
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}
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}
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}
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/* If there was a reload on channel 0, raise IRQ 0 */
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if ((i == 0) && Reloaded) PicInterruptRequest(0);
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break;
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}
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case PIT_MODE_SQUARE_WAVE:
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{
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/* Decrement the value by 2 */
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PitChannels[i].CurrentValue -= 2;
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INT ReloadCount = 0;
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WORD ReloadValue = PitChannels[i].ReloadValue;
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/* Did it fall to zero? */
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if (PitChannels[i].CurrentValue != 0) break;
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/* The reload value must be even */
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ReloadValue &= ~1;
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/* Yes, toggle the flip-flop */
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PitChannels[i].OutputFlipFlop = !PitChannels[i].OutputFlipFlop;
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/* Did this create a rising edge in the signal? */
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if (PitChannels[i].OutputFlipFlop)
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while (Count)
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{
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/* Yes, IRQ 0 if this is channel 0 */
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if (i == 0) PicInterruptRequest(0);
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}
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/* Reload the value, but make sure it's even */
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if (PitChannels[i].ReloadValue % 2)
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if (((Count * 2) > PitChannels[i].CurrentValue)
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&& (PitChannels[i].CurrentValue != 0))
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{
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/* It's odd, reduce it by 1 */
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PitChannels[i].CurrentValue = PitChannels[i].ReloadValue - 1;
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/* Decrease the count */
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Count -= PitChannels[i].CurrentValue / 2;
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/* Reload the value */
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PitChannels[i].CurrentValue = ReloadValue;
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/* Increment the reload count */
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ReloadCount++;
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}
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else
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{
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/* It was even */
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PitChannels[i].CurrentValue = PitChannels[i].ReloadValue;
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/* Clear the count */
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Count = 0;
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/* Decrease the value */
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PitChannels[i].CurrentValue -= Count * 2;
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/* Did it fall to zero? */
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if (PitChannels[i].CurrentValue == 0)
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{
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/* Reload the value */
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PitChannels[i].CurrentValue = ReloadValue;
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/* Increment the reload count */
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ReloadCount++;
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}
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}
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}
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if (ReloadCount == 0) break;
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/* Toggle the flip-flop if the number of reloads was odd */
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if (ReloadCount & 1)
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{
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PitChannels[i].OutputFlipFlop = !PitChannels[i].OutputFlipFlop;
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}
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/* Was there any rising edge on channel 0 ? */
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if ((PitChannels[i].OutputFlipFlop || ReloadCount) && (i == 0))
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{
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/* Yes, IRQ 0 */
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PicInterruptRequest(0);
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}
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break;
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@ -48,7 +48,7 @@ typedef struct _PIT_CHANNEL
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VOID PitWriteCommand(BYTE Value);
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BYTE PitReadData(BYTE Channel);
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VOID PitWriteData(BYTE Channel, BYTE Value);
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VOID PitDecrementCount();
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VOID PitDecrementCount(DWORD Count);
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DWORD PitGetResolution(VOID);
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#endif // _TIMER_H_
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