2.9.WD_Transfer()

Purpose

Executes a single read/write instruction to an I/O port or to a memory address.

Prototype
DWORD WD_Transfer(
    HANDLE hWD,
    WD_TRANSFER *pTrans);
Parameters
NameTypeInput/Output
hWDHANDLEInput
pTransWD_TRANSFER*
cmdTransDWORDInput
pPortKPTRInput
dwBytesDWORDInput
fAutoincDWORDInput
dwOptionsDWORDInput
Dataunion
*ByteBYTEInput/Output
*WordWORDInput/Output
*DwordUINT32Input/Output
*QwordUINT64Input/Output
*pBufferPVOIDInput/Output
Description
NameDescription
hWDHandle to WinDriver's kernel-mode driver as received from WD_Open()[5.2]
pTransPointer to a transfer information structure:
cmdTrans

A value indicating the type of transfer to perform — see definition of the WD_TRANSFER_CMD enumeration in windrvr.h.

In calls to WD_Transfer() the transfer command should be a read/write transfer command that conforms to the following format: <dir><p>_[S]<size>
Explanation:
<dir>: R for read, W for write
<p>: P for I/O, M for memory
<S>: signifies a string (block) transfer, as opposed to a single transfer
<size>: BYTE, WORD, DWORD or QWORD .

pPort

The memory or I/O address to access.

For a memory transfer, use the kernel-mapping of the base address received from WD_CardRegister()[2.6] in pCardReg->Card.Item[i]I.Mem.pTransAddr (where 'i' is the index of the relevant memory item) + the desired offset from the beginning of the address range.

For an I/O transfer, use the base address received from WD_CardRegister()[2.6] in pCardReg->Card.Item[i]I.IO.pAddr (where 'i' is the index of the relevant I/O item) + the desired offset from the beginning of the address range.

dwBytes Used in string transfers — number of bytes to transfer
fAutoinc Used for string transfers.
If TRUE, I/O or memory address should be incremented for transfer.
If FALSE, all data is transferred to the same port/address.
dwOptionsMust be set to 0
Data The transfer data — input for read transfers, output for write transfers:
*Byte Used for 8-bit transfers
*WordUsed for 16-bit transfers
*DwordUsed for 32-bit transfers
*QwordUsed for 64-bit transfers
*pBufferUsed for string (block) transfers
Return Value

Returns WD_STATUS_SUCCESS (0) on success, or an appropriate error code otherwise[A].

Remarks
Example
WD_TRANSFER Trans;
BYTE read_data;

BZERO(Trans);
Trans.cmdTrans = RP_BYTE; /* Read Port BYTE */
Trans.pPort = 0x210;
WD_Transfer(hWD, &Trans);
read_data = Trans.Data.Byte;