RELEASED
PM7380 FREEDM-32P672
DATA SHEET
PMC-1990262
ISSUE 5
FRAME ENGINE AND DATA LINK MANAGER 32P672
Receive Packet Descriptor Reference Ready (RPDRR) queue and the Receive
Packet Descriptor Reference Small and Large Buffer Free (RPDRF) queues.
The RMAC672 copies packet data to data buffers in host memory. The RPD,
RPDR, RPDRR queue, and Small and Large RPDRF queues are data structures
which are used to transfer host memory data buffer information. All five data
structures are manipulated by both the RMAC672 and the host computer. The
RPD holds the data buffer size, data buffer address, and packet status
information. The RPDR is a pointer which is used to index into a table of RPDs.
The RPDRR queue and RPDRF queues allow the RMAC672 and the host to
pass RPDRs back and forth. These data structures are described in more detail
in the following sections.
Receive Packet Descriptor
The Receive Packet Descriptors (RPDs) pass buffer and packet information
between the RMAC672 and the host. Both the RMAC672 and the host read and
write information in the RPDs. The host writes RPD fields which describe the
size and address of data buffers in host memory. The RMAC672 writes RPD
fields which provide number of bytes used in each data buffer, RPD link
information, and the status of the received packet. RPDs are stored in host
memory in a Receive Packet Descriptor Table which is described in a later
section. The Receive Packet Descriptor structure is shown in Figure 5.
Figure 5 – Receive Packet Descriptor
Bit 31
0
Data Buffer Start Address [31:0]
Status [5:0]
Reserved (7)
Bytes In Buffer [15:0]
RCC[9:0]
Reserved (16)
Offset[1:0]
CE
Reserved (6)
Res (1)
Next RPD Pointer [14:0]
Receive Buffer Size [15:0]
Table 6 – Receive Packet Descriptor Fields
Field
Description
Data Buffer Start
The Data Buffer Start Address[31:0] bits point to the data
buffer in host memory. This field is expected to be
configured by the Host during initialisation.
Address[31:0]
The Data Buffer Start Address field is valid in all RPDs.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA,INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
47
PMC [ PMC-SIERRA, INC ]
