ADLINK PCI-7200 - Manual (Page 70)

58 C/C++ Libraries
5.15 _7200_Alloc_DBDMA_Mem
@ Description
Contact Windows 95/98 system to allocate a block of contiguous
memory as circular buffer for double-buffered DMA DI transfer.
This function is only available in Windows 95/98 version. For dou-
ble-buffered transfering, please refer to Section 6 “Double Buff-
ered Mode Principle”.
@ Syntax
Visual C++ (Windows 95)
int W_7200_Alloc_DBDMA_Mem (U32 *buff,U32
*handle, U32 buf_size, U32 *actual_size)
Visual Basic (Windows 95)
W_7200_Alloc_DBDMA_Mem (buff As Long, handle As
Long, ByVal buf_size As Long, actual_size As
Long) As Long
@ Argument
buff: There is a dummy buffer attached to the DMA memory this
function will allocate. But this buffer needs to have size equal to or
more than buf_size bytes.
handle: The handle of system DMA memory returned from sys-
tem. Use this handle in _7200_DI_DMA_Start.
buf_size: Bytes to allocate. This is the half size of circular buffer
in byte. That is, this is the size of each half buffer in byte.
actual_size: The actual DMA memory size system allocate for
each half buffer. If system is not able to get a block of contiguous
memory of specified buf_size, it will allocate the largest block of
memory possible. In this case, this function returns
ERR_SmallerDMAMemAllocated, and actual_size denotes the
actual size of allocated memory for each half of circular buffer.
@ Return Code
ERR_NoError
ERR_SmallerDMAMemAllocated