ADLINK Technology NuDAQ User Manual

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ADLINK Technology NuDAQ User Manual Manual pdf 67 page image

C/C++ Libraries 555.13 _7200_Alloc_DMA_Mem@ DescriptionContact the Windows 95/98 system to allocate a block of contigu-ous memory for single-buffered DMA transfer. This function is onlyavailable in Windows 95/98.@ SyntaxVisual C++ (Windows 95)int W_7200_Alloc_DMA_Mem (U32 *buff, U32 *handle,U32 buf_size, U32 *actual_size)Visual Basic (Windows 95)W_7200_Alloc_DMA_Mem (buff As Long, handle AsLong, ByVal buf_size As Long, actual_size AsLong ) As Long@ Argumentbuff: The start address of the user buffer for DMA data transfer.This buffer will be attached to the DMA memory allocated by thisfunction. When using this DMA memory handle as an argument ofthe W_7200_DI_DMA_Start function, DI data will be copied to thisbuffer. When using this DMA memory handle as an argument ofthe W_7200_DO_DMA_Start function, the data stored in thisbuffer will be the DO data.handle: The handle of system DMA memory returned from sys-tem. Use this handle in _7200_DI_DMA_Start or_7200_DO_DMA_Start.buf_size: Bytes to allocate. Please be careful, the unit of thisparameter is BYTE, not SAMPLE.actual_size:The actual size system allocate for DMA memory.The unit is BYTE. If system is not able to get a block of contiguousmemory of specified buf_size, it will allocate a block of memory aslarge as it can. In this case, this function returnsERR_SmallerDMAMemAllocated, and actual_size denotes theactual size of allocated memory.