From: Alun Carp [alun@des.co.uk]
Sent: Tuesday, February 27, 2001 11:52 AM
To: NT Developers Interest List
Subject: [ntdev] RE: How to write port?

Here is a simplified copy of a port write routine we use for putting data
onto an LPT port:

notes - 
lpPortInfo paramter points to a structure containing data about the LPT port
in question, the MappedAddress member is a PHYSICAL_ADDRESS structure filled
in with a call to HalTranslateBusAddress, it contains the memory mapped
address of the physical hardware port.
PortRegister indicates which LPT register to write to, this is either 0, 1
or 2 and is used as an index into the Offsets array (member of lpPortInfo)
which contains the actual offsets to use for the registers. We have some
custom hardware which combines the status and control registers.
Data - this is the actual data byte to write to the port.


typedef struct _tPortInfo
{
    DWORD               LptNum;             // LPT Port number
    PHYSICAL_ADDRESS    DataReg;            // The Lpt Port address ie
0x378, 0x278
    PHYSICAL_ADDRESS    MappedAddress;      // The Mapped Port address
    ULONG               PortType;           // Port type - IO or Memory
    ULONG               IsPcmcia;           // Is it a PCMCIA Card?
    PHYSICAL_ADDRESS    ECPDataReg;         // The ECP Port Address
    PHYSICAL_ADDRESS    ECPMappedAddress;   // The ECP Mapped port address
    WORD                Offsets[3];         // LPT port register offsets
    struct _tPortInfo * nextPort;           // next item in the list
} PORTINFO,* PPORTINFO,FAR * LPPORTINFO;

#define DATA_OFFSET     0
#define STATUS_OFFSET   1
#define CONTROL_OFFSET  2

void PortWrite ( LPPORTINFO lpPortInfo, WORD PortRegister, BYTE Data )
{
    if( lpPortInfo )
    {
        if( PortRegister > CONTROL_OFFSET )
            PortRegister = DATA_OFFSET;
        if( lpPortInfo->PortType == 1 )
            WRITE_PORT_UCHAR( (PUCHAR) (lpPortInfo->MappedAddress.LowPart +
lpPortInfo->Offsets[PortRegister]), Data );
        else
            WRITE_REGISTER_UCHAR( (PUCHAR)
(lpPortInfo->MappedAddress.LowPart + lpPortInfo->Offsets[PortRegister]),
Data );
    }
}

Hope this helps

Alun Carp
Driver Development Team Leader
Data Encryption Systems Limited

-----Original Message-----
From: ecriee [mailto:ecriee@2911.net]
Sent: 26 February 2001 17:01
To: NT Developers Interest List
Subject: [ntdev] How to write port?


ntdev
Hi,
	I'm a beginner for writing driver in NT/2000.
	My driver works in X86 platform,so I guess I can use
WRITE_PORT_UCHAR directly,
	just like this:
				PUCHAR Port;
				UCHAR Port1,byte;

				Port1 = 0x70;
				Port = &Port1;
				byte = 0x30;

				WRITE_PORT_UCHAR( Port, byte);

	I want to write data to port 70H , but it doesn't work.
	And I think  the port maybe need to be mapped into memory space.
	Please someone tell me why & how to do it?
	Thanks for a lot.


            ecriee
            ecriee@2911.net


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