Analog Devices ADSP-SC58 Series Hardware Reference Manual page 3085

PKTE_CDRBASE_ADDR
CD0
CD1
CD2
CD3
Descriptor size
CD4
is 8 dwords
PKTE_RDRBASE_ADDR
RD0
RD1
RD2
RD3
RD4
Figure 44-3: Descriptor Rings in Autonomous Ring Mode
Description and Use of the SA Record and State Record Structure
The SA record is a packed structure that contains the remainder of the information needed by the packet engine to
process a packet. Most of the information fields in the SA record, such as the key and encryption mode, are static for
the lifetime of the association. The fields do not require frequent manipulation by the host processor. The SA record
non-static fields are the sequence number and sequence number mask.
The SA record can have a corresponding state record that is used to save results from the current operations that can
be used for future operations. The state record can hold the IV, the hash byte count, and the intermediate hash
digest.
If an SA record is used for operations that use ARC4 processing in stateful mode, it has a corresponding ARC4 state
record that holds the ARC4 State.
In this manual, the state record and the ARC4 state record are referred to as state record.
There is no practical limit to how many SA records and corresponding state records the packet engine can support.
In the autonomous ring mode and target command mode, once the packet engine has validated a command descrip-
tor, it automatically fetches the SA record and optional state record. After processing, the packet engine updates the
stateful fields in the SA record and state record in the host processor memory.
In direct host mode, after the descriptor is validated, the host must write the SA record directly into the internal
registers of the packet engine. After processing, the host reads the stateful fields from the SA registers of the packet
engine and saves them back to the SA record in the host processor memory.
SA Record Structure
The SA Record Structure table shows the structure for an SA Record. When using direct host mode, the correspond-
ing elements are accessed directly with the registers. When using autonomous ring mode or target command mode,
the SA Record is defined, configured and accessed in host memory.
ADSP-SC58x/ADSP-2158x SHARC+ Processor Hardware Reference
SRC
POINTER 0
SOURCE
PACKET 0
Descriptor Ring Size
PKTE_RING_CFG[9:0]
SOURCE
SRC
POINTER 2 PACKET 2
SRC
POINTER 1
SOURCE
PACKET 1
SOURCE
Descriptor Ring Size
PACKET 3
PKTE_RING_CFG[9:0]
SRC PACKETS, DEST. PACKETS AND
SAs CAN BE IN ANY ORDER IN
HOST MEMORY.
DEST
POINTER 0
DEST.
SA
PACKET 0 POINTER 0
DEST
DEST.
SA
POINTER 1
POINTER 1
PACKET 1
DEST
DEST.
POINTER 2
PACKET 2
DEST.
PACKET 3
SA
POINTER 1
PKTE Programming Concepts
FIXED
SA 0
SIZE
SA 1
SA 3
SA 2
44–37