lpt.c

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/*******************
* Function: line parallel port driver
* compiler: vc++ 6.0
*
* author: book
* date : 2009.03.20
********************
*/
#include "includes.h"

int validPpt; 

int GetValidPpt(void)
{
    // code can't use
    /*unsigned int *PtrAddr;
    unsigned int LptAddress;

    PtrAddr=(unsigned int *)0x00000408;
    LptAddress=*PtrAddr;
    printf("\n 1. %8x found at 0x%8x\n",(U32)LptAddress,(U32)PtrAddr);
    PtrAddr++;
    LptAddress=*PtrAddr;
    printf("\n 2. %8x found at 0x%8x\n",(U32)LptAddress,(U32)PtrAddr);
    PtrAddr++;
    LptAddress=*PtrAddr;
    printf("\n 3. %8x found at 0x%8x\n",(U32)LptAddress,(U32)PtrAddr);
    */
    // search for valid parallel port
    _outp(LPT1, 0x55);
    if((int)_inp(LPT1) == 0x55)
        return LPT1;
    
    _outp(LPT2, 0x55);
    if((int)_inp(LPT2) == 0x55)
        return LPT2;
    
    _outp(LPT3, 0x55);
    if((int)_inp(LPT3) == 0x55)
        return LPT3;
    
    return 0;   
}

#define ECP_ECR          (0x402)
#define ECR_STANDARD     (0x0)
#define ECR_DISnERRORINT (0x10)
#define ECR_DISDMA       (0x0)
#define ECR_DISSVCINT    (0x4)

void SetPptCompMode(void)
{
    //configure the parallel port at the compatibility mode.
    _outp(validPpt+ECP_ECR,(ECR_STANDARD | ECR_DISnERRORINT | ECR_DISDMA | ECR_DISSVCINT));
}

int InstallGiveIo(void)
{
    HANDLE h;
    OSVERSIONINFO osvi;
    
    osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
    GetVersionEx(&osvi);
    
    if(osvi.dwPlatformId == VER_PLATFORM_WIN32_NT)
    {
    //OS=NT/2000
    h = CreateFile("\\\\.\\giveio", GENERIC_READ, 0, NULL,
            OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
    CloseHandle(h);
    if(h == INVALID_HANDLE_VALUE)
            return 0;
    else
        return 0x2000;
    }
    else
    {   //OS=WIN98
    return 0x0098;
    }
}

void OpenLpt(void)
{
    if(!InstallGiveIo())
    {
        printf("ERROR: Couldn't open giveio.sys\n");
        exit(0);
    }

    validPpt = GetValidPpt();
    if(!validPpt)
    {
    printf("ERROR: Unable to find a parallel port\n");
    exit(0);
    }
    SetPptCompMode();   
}

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