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 #include "cpu/cpu.h"
  16
  17 // #include "clock.h"
  18
  19 #include "hardware/cmos.h"
  20 #include "hardware/ps2.h"
  21 #include "hardware/timer.h"
  22 #include "hardware/vga.h"
  23
  24 /* DEFINES ********************************************************************/
  25
  26 /*
  27  * Activate IPS_DISPLAY if you want to display the
  28  * number of instructions per second, as well as
  29  * the computed number of ticks for the PIT.
  30  */
  31 // #define IPS_DISPLAY
  32
  33 /*
  34  * Activate WORKING_TIMER when the PIT timing problem is fixed.
  35  */
  36 // #define WORKING_TIMER
  37
  38
  39 /* Processor speed */
  40 #define STEPS_PER_CYCLE 256
  41 #define IRQ1_CYCLES     16
  42 #define IRQ12_CYCLES    16
  43
  44 /* VARIABLES ******************************************************************/
  45
  46 LARGE_INTEGER StartPerfCount, Frequency;
  47
  48 LARGE_INTEGER LastTimerTick, LastRtcTick, Counter;
  49 LONGLONG TimerTicks;
  50 DWORD StartTickCount, CurrentTickCount;
  51 DWORD LastClockUpdate;
  52 DWORD LastVerticalRefresh;
  53
  54 UINT Irq1Counter = 0;
  55 UINT Irq12Counter = 0;
  56
  57 #ifdef IPS_DISPLAY
  58     DWORD LastCyclePrintout;
  59     DWORD Cycles = 0;
  60 #endif
  61
  62 /* PUBLIC FUNCTIONS ***********************************************************/
  63
  64 VOID ClockUpdate(VOID)
  65 {
  66     extern BOOLEAN CpuRunning;
  67     UINT i;
  68
  69 #ifdef WORKING_TIMER
  70     DWORD PitResolution = PitGetResolution();
  71 #endif
  72     DWORD RtcFrequency = RtcGetTicksPerSecond();
  73
  74     /* Get the current number of ticks */
  75     CurrentTickCount = GetTickCount();
  76
  77 #ifdef WORKING_TIMER
  78     if ((PitResolution <= 1000) && (RtcFrequency <= 1000))
  79     {
  80         /* Calculate the approximate performance counter value instead */
  81         Counter.QuadPart = StartPerfCount.QuadPart
  82                            + (CurrentTickCount - StartTickCount)
  83                            * (Frequency.QuadPart / 1000);
  84     }
  85     else
  86 #endif
  87     {
  88         /* Get the current performance counter value */
  89         QueryPerformanceCounter(&Counter);
  90     }
  91
  92     /* Get the number of PIT ticks that have passed */
  93     TimerTicks = ((Counter.QuadPart - LastTimerTick.QuadPart)
  94                  * PIT_BASE_FREQUENCY) / Frequency.QuadPart;
  95
  96     /* Update the PIT */
  97     if (TimerTicks > 0)
  98     {
  99         PitClock(TimerTicks);
 100         LastTimerTick = Counter;
 101     }
 102
 103     /* Check for RTC update */
 104     if ((CurrentTickCount - LastClockUpdate) >= 1000)
 105     {
 106         RtcTimeUpdate();
 107         LastClockUpdate = CurrentTickCount;
 108     }
 109
 110     /* Check for RTC periodic tick */
 111     if ((Counter.QuadPart - LastRtcTick.QuadPart)
 112         >= (Frequency.QuadPart / (LONGLONG)RtcFrequency))
 113     {
 114         RtcPeriodicTick();
 115         LastRtcTick = Counter;
 116     }
 117
 118     /* Check for vertical retrace */
 119     if ((CurrentTickCount - LastVerticalRefresh) >= 15)
 120     {
 121         VgaRefreshDisplay();
 122         LastVerticalRefresh = CurrentTickCount;
 123     }
 124
 125     if (++Irq1Counter == IRQ1_CYCLES)
 126     {
 127         GenerateIrq1();
 128         Irq1Counter = 0;
 129     }
 130
 131     if (++Irq12Counter == IRQ12_CYCLES)
 132     {
 133         GenerateIrq12();
 134         Irq12Counter = 0;
 135     }
 136
 137     /* Horizontal retrace occurs as fast as possible */
 138     VgaHorizontalRetrace();
 139
 140     /* Continue CPU emulation */
 141     for (i = 0; VdmRunning && CpuRunning && (i < STEPS_PER_CYCLE); i++)
 142     {
 143         CpuStep();
 144 #ifdef IPS_DISPLAY
 145         Cycles++;
 146 #endif
 147     }
 148
 149 #ifdef IPS_DISPLAY
 150     if ((CurrentTickCount - LastCyclePrintout) >= 1000)
 151     {
 152         DPRINT1("NTVDM: %lu Instructions Per Second; TimerTicks = %I64d\n", Cycles * 1000 / (CurrentTickCount - LastCyclePrintout), TimerTicks);
 153         LastCyclePrintout = CurrentTickCount;
 154         Cycles = 0;
 155     }
 156 #endif
 157 }
 158
 159 BOOLEAN ClockInitialize(VOID)
 160 {
 161     /* Initialize the performance counter (needed for hardware timers) */
 162     if (!QueryPerformanceFrequency(&Frequency))
 163     {
 164         wprintf(L"FATAL: Performance counter not available\n");
 165         return FALSE;
 166     }
 167
 168     /* Find the starting performance and tick count */
 169     StartTickCount = GetTickCount();
 170     QueryPerformanceCounter(&StartPerfCount);
 171
 172     /* Set the different last counts to the starting count */
 173     LastClockUpdate = LastVerticalRefresh =
 174 #ifdef IPS_DISPLAY
 175     LastCyclePrintout =
 176 #endif
 177     StartTickCount;
 178
 179     /* Set the last timer ticks to the current time */
 180     LastTimerTick = LastRtcTick = StartPerfCount;
 181
 182     return TRUE;
 183 }