VDDRequestDMA

DWORD VDDRequestDMA(hVDD, iChannel, Buffer, length)
IN HANDLE  hVDD;
WORD  iChannel;
PVOID  Buffer;
DWORD  length;

VDDRequestDMA requests a DMA transfer from a VDD.

Parameters

hVDD

Identifies the VDD.

iChannel

Specifies the DMA channel for the transfer operation.

Buffer

Points to the buffer to or from which the data is transferred.

length

Specifies the size in bytes of the transfer count. If length is 0, the current transfer count is returned.

Return Value

VDDRequestDMA returns the number of bytes transferred. If zero is returned and GetLastError (see the Win32 SDK) is set, then the operation failed. If zero is returned and GetLastError is clear, then the DMA transfer count was zero.

The extended error codes is ERROR_INVALID_ADDRESS which identifies an invalid channel.

Comments

VDDs that need to carry out DMA operations but that do not need to deal with all DMA registers should call this function.

Using this function is slower than using VDDQueryDMA and VDDSetDMA.

See Also

VDDQueryDMA, VDDSetDMA