Freescale Semiconductor MPC8313E PowerQUICC II Pro Family Reference Manual page 659

Bit # 0
SEGLEN
Bits Name
0–15 SEGLEN Length. When N=0, a number in the range 1–65535, specifying the number of bytes in the memory
segment. pointed to by SEGADR. A value of 0 will cause an error state to be set in the channel pointer
status register—G-STATE for a gather operation or S-STATE for a scatter operation (see
"Crypto-Channel Pointer Status Register
When N = 1, must be 0.
16–21 — Reserved
22 R Return. When N=0:
0 No special action.
1 This is the last entry in the chain of link tables. If this entry does not specify the right number of bytes
to complete the last data parcel, a G-STATE or S-STATE error will be set in the channel pointer status
register (see
When N = 1, ignored.
23 N Next
0 No special action.
1 This is the last long word in the current link table. The SEGADR field is the address of the next link
table in the chain.
24-31 — Reserved
32–63 SEGADR Segment address. A memory address.
For any sequence of data parcels accessed by a link table or chain of link tables, the combined lengths of
the parcels (the sum of their LENGTH and/or EXTENT fields) must equal the combined lengths of the link
table memory segments (SEGLEN fields). Otherwise the channel sets the appropriate error state in the
channel pointer status register—G-STATE for gather error or S-STATE for scatter error (see
Section 14.5.1.2, "Crypto-Channel Pointer Status Register
Example (from
type calls for the channel to read a data parcel using Pointer3 and Extent3 fields, and assume that
J3 = 1. Due to the J3 value, Pointer3 is not used as a data address but instead used as the address
of a link table. The channel begins by reading the first four long words starting at Pointer3 into an
internal 'gather table buffer.'
Using the first entry of the gather table buffer, the channel starts accessing the data parcel by
reading SEGLEN bytes beginning at SEGADR. If the required data parcel size (Extent3) is greater
than this first SegLen, the channel moves on to the next entry of the gather table buffer, and reads
SEGLEN bytes starting at SEGADR. While there are more bytes to be read in the data parcel, this
process continues. If the channel's gather table buffer is exhausted, the channel reads the next four
long words of the link table into its gather table buffer. If a gather table buffer entry is encountered
in which the N bit is set, the channel uses the SEGADR field in that word to find the next link table
in the chain. The last byte of the required parcel size (Extent3) must coincide with the last byte of
a memory segment, or unpredictable results may occur.
MPC8313E PowerQUICC™ II Pro Integrated Processor Family Reference Manual, Rev. 2
Freescale Semiconductor
15 16 21 22
— R
Figure 14-6. Link Table Entry
Table 14-9. Link Table Field Definitions
Section 14.5.1.2, "Crypto-Channel Pointer Status Register
)
Figure 14-6 : To demonstrate use of a link table, assume that the current descriptor
23 24 31
N —
Description
(CCPSR)").
(CCPSR)").
Security Engine (SEC) 2.2
32
SEGADR
Section 14.5.1.2,
(CCPSR)").
63
14-17