Alt_avalon_sgdma_construct_mem_to_stream_desc() – Altera Embedded Peripherals IP User Manual
Page 212
Description:
This function constructs a single SG-DMA descriptor in the memory specified in
alt_avalon_sgdma_descriptor
*desc for an Avalon-ST to Avalon-MM
transfer. The source (read) data for the transfer comes from the Avalon-ST
interface connected to the SG-DMA controller's streaming read port.
The function sets the OWNED_BY_HW bit in the descriptor's control field,
marking the completed descriptor as ready to run. The descriptor is processed
when the SG-DMA controller receives the descriptor and the RUN bit is 1.
The next field of the descriptor being constructed is set to the address in *next.
The OWNED_BY_HW bit of the descriptor at *next is explicitly cleared. Once
the SG-DMA completes processing of the *desc, it does not process the
descriptor at *next until its OWNED_BY_HW bit is set. To create a descriptor
chain, you can repeatedly call this function using the previous call's *next pointer
in the *desc parameter.
You must properly allocate memory for the creation of both the descriptor under
construction as well as the next descriptor in the chain.
Descriptors must be in a memory device mastered by the SG-DMA controller’s
chain read and chain write Avalon master ports. Care must be taken to ensure
that both *desc and *next point to areas of memory mastered by the controller.
alt_avalon_sgdma_construct_mem_to_stream_desc()
Prototype:
void alt_avalon_sgdma_construct_mem_to_stream_desc(alt_sgdma_descriptor
*desc, alt_sgdma_descriptor *next, alt_u32 *read_addr, alt_u16 length, int read_
fixed, int generate_sop, int generate_eop, alt_u8 atlantic_channel)
Thread-safe:
Yes.
Available
from ISR:
Yes.
Include:
<altera_avalon_sgdma.h>, <altera_avalon_sgdma_descriptor.h>, <altera_
avalon_sgdma_regs.h>
UG-01085
2014.24.07
alt_avalon_sgdma_construct_mem_to_stream_desc()
21-21
Scatter-Gather DMA Controller Core
Altera Corporation