reactos/subsystems/ntvdm/clock.c

   1 /*
   2  * COPYRIGHT:       GPL - See COPYING in the top level directory
   3  * PROJECT:         ReactOS Virtual DOS Machine
   4  * FILE:            clock.c
   5  * PURPOSE:         Clock for VDM
   6  * PROGRAMMERS:     Aleksandar Andrejevic <theflash AT sdf DOT lonestar DOT org>
   7  *                  Hermes Belusca-Maito (hermes.belusca@sfr.fr)
   8  */
   9
  10 /* INCLUDES *******************************************************************/
  11
  12 #define NDEBUG
  13
  14 #include "emulator.h"
  15
  16 // #include "clock.h"
  17
  18 #include "hardware/cmos.h"
  19 #include "hardware/ps2.h"
  20 #include "hardware/timer.h"
  21 #include "hardware/vga.h"
  22
  23 /* DEFINES ********************************************************************/
  24
  25 /*
  26  * Activate IPS_DISPLAY if you want to display the
  27  * number of instructions per second, as well as
  28  * the computed number of ticks for the PIT.
  29  */
  30 // #define IPS_DISPLAY
  31
  32 /*
  33  * Activate WORKING_TIMER when the PIT timing problem is fixed.
  34  */
  35 // #define WORKING_TIMER
  36
  37
  38 /* Processor speed */
  39 #define STEPS_PER_CYCLE 256
  40 #define KBD_INT_CYCLES 16
  41
  42 /* VARIABLES ******************************************************************/
  43
  44 LARGE_INTEGER StartPerfCount, Frequency;
  45
  46 LARGE_INTEGER LastTimerTick, LastRtcTick, Counter;
  47 LONGLONG TimerTicks;
  48 DWORD StartTickCount, CurrentTickCount;
  49 DWORD LastClockUpdate;
  50 DWORD LastVerticalRefresh;
  51 INT KeyboardIntCounter = 0;
  52
  53 #ifdef IPS_DISPLAY
  54     DWORD LastCyclePrintout;
  55     DWORD Cycles = 0;
  56 #endif
  57
  58 /* PUBLIC FUNCTIONS ***********************************************************/
  59
  60 VOID ClockUpdate(VOID)
  61 {
  62     extern BOOLEAN CpuSimulate;
  63     UINT i;
  64
  65 #ifdef WORKING_TIMER
  66     DWORD PitResolution = PitGetResolution();
  67 #endif
  68     DWORD RtcFrequency = RtcGetTicksPerSecond();
  69
  70     /* Get the current number of ticks */
  71     CurrentTickCount = GetTickCount();
  72
  73 #ifdef WORKING_TIMER
  74     if ((PitResolution <= 1000) && (RtcFrequency <= 1000))
  75     {
  76         /* Calculate the approximate performance counter value instead */
  77         Counter.QuadPart = StartPerfCount.QuadPart
  78                            + (CurrentTickCount - StartTickCount)
  79                            * (Frequency.QuadPart / 1000);
  80     }
  81     else
  82 #endif
  83     {
  84         /* Get the current performance counter value */
  85         QueryPerformanceCounter(&Counter);
  86     }
  87
  88     /* Get the number of PIT ticks that have passed */
  89     TimerTicks = ((Counter.QuadPart - LastTimerTick.QuadPart)
  90                  * PIT_BASE_FREQUENCY) / Frequency.QuadPart;
  91
  92     /* Update the PIT */
  93     if (TimerTicks > 0)
  94     {
  95         PitClock(TimerTicks);
  96         LastTimerTick = Counter;
  97     }
  98
  99     /* Check for RTC update */
 100     if ((CurrentTickCount - LastClockUpdate) >= 1000)
 101     {
 102         RtcTimeUpdate();
 103         LastClockUpdate = CurrentTickCount;
 104     }
 105
 106     /* Check for RTC periodic tick */
 107     if ((Counter.QuadPart - LastRtcTick.QuadPart)
 108         >= (Frequency.QuadPart / (LONGLONG)RtcFrequency))
 109     {
 110         RtcPeriodicTick();
 111         LastRtcTick = Counter;
 112     }
 113
 114     /* Check for vertical retrace */
 115     if ((CurrentTickCount - LastVerticalRefresh) >= 15)
 116     {
 117         VgaRefreshDisplay();
 118         LastVerticalRefresh = CurrentTickCount;
 119     }
 120
 121     if (++KeyboardIntCounter == KBD_INT_CYCLES)
 122     {
 123         GenerateKeyboardInterrupts();
 124         KeyboardIntCounter = 0;
 125     }
 126
 127     /* Horizontal retrace occurs as fast as possible */
 128     VgaHorizontalRetrace();
 129
 130     /* Continue CPU emulation */
 131     for (i = 0; VdmRunning && CpuSimulate && (i < STEPS_PER_CYCLE); i++)
 132     {
 133         EmulatorStep();
 134 #ifdef IPS_DISPLAY
 135         Cycles++;
 136 #endif
 137     }
 138
 139 #ifdef IPS_DISPLAY
 140     if ((CurrentTickCount - LastCyclePrintout) >= 1000)
 141     {
 142         DPRINT1("NTVDM: %lu Instructions Per Second; TimerTicks = %I64d\n", Cycles, TimerTicks);
 143         LastCyclePrintout = CurrentTickCount;
 144         Cycles = 0;
 145     }
 146 #endif
 147 }
 148
 149 BOOLEAN ClockInitialize(VOID)
 150 {
 151     /* Initialize the performance counter (needed for hardware timers) */
 152     if (!QueryPerformanceFrequency(&Frequency))
 153     {
 154         wprintf(L"FATAL: Performance counter not available\n");
 155         return FALSE;
 156     }
 157
 158     /* Find the starting performance and tick count */
 159     StartTickCount = GetTickCount();
 160     QueryPerformanceCounter(&StartPerfCount);
 161
 162     /* Set the different last counts to the starting count */
 163     LastClockUpdate = LastVerticalRefresh =
 164 #ifdef IPS_DISPLAY
 165     LastCyclePrintout =
 166 #endif
 167     StartTickCount;
 168
 169     /* Set the last timer ticks to the current time */
 170     LastTimerTick = LastRtcTick = StartPerfCount;
 171
 172     return TRUE;
 173 }