Help: ICE_ICELIB_PIC_MAPFILE

Prepares a Midas file/buffer for DMA transfers

Function PIC_MAPFILE - Prepares a Midas file/buffer for DMA transfers

PIC	p	Handle to Device 
DMAMAP	map	DMAMAP structure to contain virtual and physical pointers
HEADER	hcb	Header Control Block of a Midas file
int	mode	Access mode (1=allocate, -1=deallocate)

Prepares a Midas file for DMA transfers.  It the file is on a RAMDISK the 
start and count map to the actual disk address.  If not, a memory buffer
matching the file size is allocated and mapped to DMA address space.  
If memory is not mappable (or mode=2,-2) paddr is set to zero and a
virtual buffer is allocated but not mapped.  This buffer is usable for 
non-DMA access which limits speeds to ~10Mby/sec.

The map structure is inputs to the PIC_DMASETUP routine.  These numbers
are checked by the driver to ensure the addresses are valid before the DMA is
started.