RE: [ethmac] CRC

["Illan Glasner" <iglasner@zumanetworks.com>]

   Hi,

      Assuming all you want to do is test the packet you received have a correct crc you shouldn't need to make any specail case for the crc word simple pass it as you did with all the other data nibble and see that at the end you get the "magic-number".

also don't forget to initial the 32FF in the crc to all "1" for each new packet.

the only time you need to do some "modification" is when you generate crc as than you do need to swap the bits as well as invert them before attaching the crc to the back of the packet.

have a nice day

   Illan


-----Original Message-----
From: eddie_7_taylor@hotmail.com [mailto:eddie_7_taylor@hotmail.com]
Sent: Wednesday, April 24, 2002 4:43 AM
To: ethmac@opencores.org
Subject: [ethmac] CRC


Having developed a custom MAC with Dual RX FIFO memories, I have 
taken just the CRC generator section (eth_crc) to use in our design.

I wanted to know whether there was anything special I need to do in 
order to get CRC agreement other than this:

- Feed the CRC from the raw MII nibbles, with the bits transposed in the 
RX_MAC module (0 -> 3, 1-> 2, 2-> 1, 3->0)

- Initialise on the first true data nibble after SFD.

Ed
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