Maxim Integrated 78Q8430 Software Driver - Manual (Page 33)

UG_8430_004 78Q8430 Software Driver Development Guidelines
Rev. 1.0 33
Data Mask 0xFF
Previous Hit Match 0x7B
Previous Hit Mask 0x7F
Byte Offset 0x01 (to skip over the TTL field and look at Protocol)
Interrupt Retain default: 0
Control Logic Action NOP
RCR
Match Control MD
STEP 4: Set CAM rule 0x79 to verify the protocol is ICMP.
Reg. Field Value to write
CAR ADDR 0x79
Data Match 0x01
Data Mask 0xFF
Previous Hit Match 0x7A
RMR
Previous Hit Mask 0x7F
Byte Offset 0x3F (to skip over the IP header)
Interrupt Retain default: 0
Control Logic Action NOP
RCR
Match Control MD
STEP 5: Set rule 0x78 to verify the ICMP type is echo request.
Reg. Field Value to write
CAR ADDR 0x78
Data Match 0x08
Data Mask 0xFF
Previous Hit Match 0x79
RMR
Previous Hit Mask 0x7F
Byte Offset 0x00
Interrupt Retain default: 0
Control Logic Action NOP
RCR
Match Control DONE
Process the ICMP Echo Reply
Use the following procedure to transmit an ICMP echo reply in response to an ICMP echo request:
STEP 1: Check that the classification result is 0x78.
The RPSR Classification field value is 0x78 when the frame is an ICMP echo request.
STEP 2: Read the QUE 0 QLFR to obtain the BLOCK number for the ICMP echo request frame.
When the ICMP request is the next frame in the receive QUE, the QUE 0 QFLR First field contains
the BLOCK number of the frame.
STEP 3: Configure SNOOP to access the ICMP request frame.
Write the value contained in the QFLR First field to the SNCR BLOCK field to configure the SNOOP
interface to access the ICMP frame.