
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
44
Although a STATUS+RPDR only totals to 16 bits, each queue entry is a dword,
i.e. 32 bits. When the RMAC block writes a STATUS+RPDR to the ready queue,
it sets the third byte to 0 and the fourth (most significant) byte is unmodified.
Figure 7 – RPDRR Queue Operation
Rx Packet Descriptor Reference Ready Queue
Bit 0
Bit 31
STATUS + RPDR
STATUS + RPDR
STATUS + RPDR
RPDRRQ_START_ADDR
RPDRRQ_END_ADDR
RPDRRQ_READ_ADDR
RPDRRQ_WRITE_ADDR
RPD - 16 bytes
RPD - 16 bytes
RPD - 16 bytes
RPD - 16 bytes
RPD - 16 bytes
buffer
-packet M
buffer
-packet N
buffer
-start of
packet O
buffer
-middle of
packet O
buffer
-end of
packet O
Receive Channel Descriptor Reference Table
On a per-channel basis, the RMAC caches information such as the current DMA
information in a Receive Channel Descriptor Reference (RCDR) Table. The
RMAC can process 32 channels and stores three dwords of information per
channel. This information is cached internally in order to decrease the number
of host bus accesses required to process each data packet. The structure of the
RCDR table is shown in Figure 8.