WDC_DMASGBufLock()

DWORD DLLCALLCONV WDC_DMASGBufLock	(	_In_ WDC_DEVICE_HANDLE	hDev,
		_In_ PVOID	pBuf,
		_In_ DWORD	dwOptions,
		_In_ DWORD	dwDMABufSize,
		_Outptr_ WD_DMA **	ppDma
	)

Locks a pre-allocated user-mode memory buffer for DMA and returns the corresponding physical mappings of the locked DMA pages.

On Windows the function also returns a kernel-mode mapping of the buffer.

Parameters

[in]	hDev	Handle to a WDC device, returned by WDC_xxxDeviceOpen()
[in]	pBuf	Pointer to a user-mode buffer to be mapped to the allocated physical DMA buffer(s)
[in]	dwOptions	A bit mask of any of the following flags (defined in an enumeration in windrvr.h): DMA_FROM_DEVICE: Synchronize the DMA buffer for transfers from the device to memory. DMA_TO_DEVICE: Synchronize the DMA buffer for transfers from memory to the device. DMA_TO_FROM_DEVICE: Synchronize the DMA buffer for transfers in both directions i.e., from the device to memory and from memory to the device (<=> DMA_FROM_DEVICE | DMA_TO_DEVICE). DMA_ALLOW_CACHE: Allow caching of the memory. DMA_ALLOW_64BIT_ADDRESS: Allow allocation of 64-bit DMA addresses.
[in]	dwDMABufSize	The size (in bytes) of the DMA buffer.
[out]	ppDma	Pointer to a pointer to a DMA buffer information structure, which is allocated by the function. The pointer to this structure (*ppDma) should be passed to WDC_DMABufUnlock() when the DMA buffer is no longer needed.

Returns

Returns WD_STATUS_SUCCESS (0) on success, or an appropriate error code otherwise

For more detailed usage of the WDC Scatter/Gather DMA implementaiton, please refer to 11.2.1. Implementing Scatter/Gather DMA