
DATA SHEET
PM7367 FREEDM-32P32
ISSUE 2
PMC-1991499
FRAME ENGINE AND DATA LINK MANAGER
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMER’S INTERNAL USE
37
Packet Descriptor Reference Ready (RPDRR) queue and the Receive Packet
Descriptor Reference Small and Large Buffer Free (RPDRF) queues.
The RMAC 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 RMAC 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 RMAC 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 RMAC and the host. Both the RMAC 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 RMAC 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 4.
Figure 4 – Receive Packet Descriptor
Reserved (18)
CE
Next RPD Pointer [13:0]
Status [5:0]
RCC [6:0]
Data Buffer Start Address [31:0]
Receive Buffer Size [15:0]
0
Bit 31
Bytes In Buffer [15:0]
Reserved (16)
Offset[1:0]
Table 6 – Receive Packet Descriptor Fields
Field
Data Buffer Start
Address[31:0]
Description
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.
The Data Buffer Start Address field is valid in all RPDs.