microcontroller router in micro C 16f887

[zemzela]

program the PIC to work as a Super Router, and reading the serial
port frame, forwards them to the standard, or rejected. The next message
format:
First Destination MAC, 6 bytes fixed - variable value for each frame
Second TTL, 1 byte fixed - variable value for each frame
Third Length, 1 byte fixed - variable value for each frame
4th Data, [1, 16] bytes - variable value, variable length for each frame
5th Error Code, 1 byte fixed - sum of all units in the field 1-4
And process the PIC as follows:
First Checking the MAC address.
- If it is rejected and the LCD display reads in two lines - "Primiv
ramka sto ne e za mene ".
- If it is addressed, go to step 2
Second Checking the Error Code.
- If the frame is error, rejecting the LCD screen and write in two rows -
"Primiv ramka sto gresna".
- If the frame is not an error, go to step 3
Third Check the TTL.
- If the TTL is 0, the frame is discarded and the LCD display reads in two rows -
"Primiv ramka sto TTL = 0".
- If TTL> 0, go to step 4.
4th Creating a framework for sending.
- In the Dest. MAC value is entered as DestMac own arbitrary will
create it as a variable
- TTL field is reduced by 1 from the received frame
- Length field remains the same
- Data remains the same field
- Calculate new value for the Error Code field
After creating the frame, it sends the serial port, and write the first row of the LCD
- "Prativ ramka:", second row area Data
After sending, wait for a new framework. Assume that in the meantime not to arrive
new framework


This is my project, please help me...