SPRUJ17H March 2022 – October 2024 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1
The 4-byte checksum encapsulation word is included as the first 4-bytes of the receive packet data when SOP buffer descriptor CHKSUM_ENCAP is set. The PACKET_LENGTH includes the four encapsulation bytes.
31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 |
CHECKSUM_RESULT | CHECKSUM_START_BYTE | ||||||||||||||
15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
CHKSUM_INV | RESERVED | CHECKSUM_BYTECOUNT |
Bit | Field | Description |
---|---|---|
31-24 | CHECKSUM_RESULT | Checksum Result Byte Location. This is the packet byte number where the checksum result will be placed in the egress packet. The first packet byte which is the first byte of the destination address is byte 1 (not byte zero). |
23-16 | CHECKSUM_START_BYTE | Checksum Start Byte. This is the packet byte number to start the checksum calculation on. The first packet byte is byte 1. |
15 | CHKSUM_INV | Checksum Invert Zero. When set, a zero checksum value will be inverted and sent as 0xFFFF. |
14 | RESERVED | Reserved |
13-0 | CHECKSUM_BYTECOUNT | Checksum Byte Count. This is the number of bytes to calculate the checksum on. The outgoing Ethernet packet will have a checksum inserted when this value is non-zero. |