How to use Single CRC crcu with sec engine 3.3 at platform P1020?

[quanliwang]

Hi,

  I am using crcu with sec engine 3.3 at platform P1020 and I have a question, see the following.

  Accoring to the doc 'AN3645.pdf' (SEC 2/3x Descriptor Programmer’s Guide), &3.2 Descriptor Type 0001_0: common_nonsnoop (P20 ), see Single CRC at Table 12, there are 4 items:

1. 'Primary EU Context In' at L1

2. 'Data In ' at L3

3. 'CRC In' at E4

4. 'CRC Out' at L5

I don't clear what these words means.

When I do crc, I use 3 items as input and get 1 output.

3 input-items include: input-data, polynomial, and init-crc-in

1 outpu item: crc-out, as result

What's the relation between them?

Could you please give a detail about 4 items about Single CRC in  'AN3645.pdf'.

Also, what's the difference using Outbound or Inbound to do single crc ?

Thanks

[r8070z · Accepted solution]

Have a great day,

'Primary EU Context In' and 'CRC In' are shaded in the Table 9 and Table 12 of the 'AN3645.pdf’. As explained before Table 9  an optional fields are shaded (i.e. shaded field may not be required).

Table 8. Common Descriptor Fields of the 'AN3645.pdf’ explains 'Primary EU Context In'. It may be needed only in a continuing descriptor to load the intermediate output by a previous descriptor. “CRC In” the Table 9 and 12 are the same as “RICV In” in the Table 8. I.e. if CRC checking is selected, this field in the descriptor is used to identify the received CRC so that it can be compared to the internally computed CRC.

Hence if you are going to calculate the CRC you may need only for “Data in” (input data length and input data pointer) and “CRC out” (length=4 and pointer for calculated CRC).

> Also, what's the difference using Outbound or Inbound to do single crc

It is not clear what do you mean. If you refer to the DIR bit then see section 2.4 Direction Bit in 'AN3645.pdf'. For description type 0001_0: common_nonsnoop this bit is ignored.

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