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Extension Examples->Counters 0 and 1->Extension Source Code

/*
* This single file is a complete extension, written in C, for the Crossware 8051 Virtual Workshop.
* It increments counter 0 every 5 machine cycles and increments counter 1 every 50 machine cycles.
*
* As written (ie using DllExport), it will compile with the Microsoft Visual C++ compiler.
*
* Copyright (c) 1998 Crossware Products.
*
* This source code is provided as an example to complement the Crossware 8051 Virtual Workshop.
*/

#define DllExport __declspec( dllexport )

#define LONG long
#define BYTE unsigned char

#define TRUE 1
#define FALSE 0

LONG g_nMachineCycles;
LONG g_nCounter0Cycles;
LONG g_nCounter1Cycles;

LONG* g_pnError;    // placing a non-zero value in here will halt the simulator

DllExport LONG Initialise(LONG* pnError)
{
    g_pnError = pnError;    // save the address of the simulators error indicator
    return 1;    // must return a non-zero value otherwise extension will be ignored
}

DllExport void SetMachineCycles(LONG nExtensionState, LONG nCycles)
{
    g_nMachineCycles = nCycles;
}

DllExport void IncMachineCycles(LONG nExtensionState, LONG nCycles)
{
    // we need to keep track of the machine cycles so intercept this call
    g_nMachineCycles += nCycles;
}

DllExport void GetPortPins(LONG nExtensionState, BYTE nPortAddress, BYTE* pnPins, BYTE* pnHandledPins, LONG bSimulating)
{
    // Clear or set only the pins relevant to this extension
    // If you set or clear any of the pins, then set the corresponding bit in pnHandledPins
    if (nPortAddress == 0XB0)
    {
        // Port 3
        // one count every 5 machine cycles
        if (g_nMachineCycles - g_nCounter0Cycles > 5)
        {
            *pnPins &= ~0X10;    // clear the pin P3.4 to trigger counter 0
            g_nCounter0Cycles = g_nMachineCycles;
        }
        else
            *pnPins |= 0X10;    // set the pin
        *pnHandledPins |= 0X10;    // tell the simulator that we have handled this pin

        // one count every 50 machine cycles
        if (g_nMachineCycles - g_nCounter1Cycles > 50)
        {
            *pnPins &= ~0X20;    // clear the pin P3.5 to trigger counter 1
            g_nCounter1Cycles = g_nMachineCycles;
        }
        else
            *pnPins |= 0X20;    // set the pin
        *pnHandledPins |= 0X20;    // tell the simulator that we have handled this pin
    }
}

DllExport void ResetState(LONG nExtensionState)
{
    // simulator is being reset, reset our own variables
    g_nMachineCycles = 0;
    g_nCounter0Cycles = 0;
    g_nCounter1Cycles = 0;
}