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about SetInvalidSymbol
by ybhuang on Mar 11, 2004
ybhuang
Posts: 1
Joined: Mar 25, 2011
Last seen: Sep 22, 2023
Hi,
I find in module eth_macstatus.v ,we define

assign SetInvalidSymbol = MRxDV & MRxErr & MRxD[3:0] == 4'he;

but in IEEE Std 802.3, 2000 Edition ,it suggest if MRXDV assert and MRXERR assert ,
the packet is invalid. why in this module ,you must add " MRxD[3:0] == 4'he"





======= 2004-03-01 18:28:00 ÄúÔÚÀ´ÐÅÖÐдµÀ£º=======

Hi, I'm in the process of writing a HDLC mapper and I looked into the mailing list and found the discussion attached below. My question is, if you do not know what length the packet is in advance, how do you solve the initialization problem ? I do not wish to buffer the entire packet before I can calculate the CRC on it. Is there a solution to that, or am I completly on the wrong track ? Thanks, Erez. Attached msg below: Mathew Hi, The idea behind unaligned width is that indeed as you understood we pad with "enough" "same pattern" to fill and align the width. now that we have the padding you data is align so this part is solved. the problem you need now to solve is that you don;t really want to calculate the crc of the padding as this is just for alignment purpose. and so the solution is that you do "back calculation" of the crc and find the initial crc value that once tha padding pass through it you get all "1" and so your crc machine caluclate in reality only the data. this way you get calculation of only the real data as well as your data is align. I'm off for almost 4 weeks, so if you have more question I'm sure other can also help and if not once I'm back I will try to answer what still is not clear. good luck and have fun with your crc machines. Illan _______________________________________________ http://www.opencores.org/mailman/listinfo/ethmac
= = = = = = = = = = = = = = = = = = = = ¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡Ö Àñ£¡ ¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡ybhuang ¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡ybhuang@fiberhome.com.cn ¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡2004-03-11
about SetInvalidSymbol
by Unknown on Mar 11, 2004
Not available!
We are talking here about invalid symbol, not invalid packet.

Invalid symbol is when only half of byte (one nibble) is received.
It is reported by the PHY by sending 4'he.


Regards,
Igor



-----Original Message----- From: ethmac-bounces@opencores.org
[mailto:ethmac-bounces@opencores.org]
On Behalf Of ybhuang
Sent: Thursday, March 11, 2004 7:32 AM
To: List about open source Ethernet MAC core
Subject: [ethmac] about SetInvalidSymbol

Hi,
I find in module eth_macstatus.v ,we define

assign SetInvalidSymbol = MRxDV & MRxErr & MRxD[3:0] == 4'he;

but in IEEE Std 802.3, 2000 Edition ,it suggest if MRXDV assert and
MRXERR assert ,
the packet is invalid. why in this module ,you must add " MRxD[3:0]

==
4'he"





======= 2004-03-01 18:28:00 ÄúÔÚÀ´ÐÅÖÐдµÀ£º=======

>Hi,
>
> I'm in the process of writing a HDLC mapper and I looked into the

mailing
>list and found the discussion attached below.
>
> My question is, if you do not know what length the packet is in

advance, how
>do you solve the initialization problem ? I do not wish to buffer the

entire
>packet before I can calculate the CRC on it.
>
> Is there a solution to that, or am I completly on the wrong track ?
>
> Thanks,
> Erez.
>
>Attached msg below:
>
>
> Mathew Hi,
>
> The idea behind unaligned width is that indeed as you understood

we
>pad with "enough" "same pattern" to fill and align the width.
>
>now that we have the padding you data is align so this part is

solved.
>
>the problem you need now to solve is that you don;t really want to

calculate
>the crc of the padding as this is just for alignment purpose.
>
>and so the solution is that you do "back calculation" of the crc and

find
>the initial crc value that once tha padding pass through it you get

all
"1"
>and so your crc machine caluclate in reality only the data.
>
>this way you get calculation of only the real data as well as your

data
is
>align.
>
>I'm off for almost 4 weeks, so if you have more question I'm sure

other
can
>also help and if not once I'm back I will try to answer what still is

not
>clear. > >good luck and have fun with your crc machines. > > Illan > >_______________________________________________ >http://www.opencores.org/mailman/listinfo/ethmac
= = = = = = = = = = = = = = = = = = = = ¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡Ö Àñ£¡ ¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡ybhuang ¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡ybhuang@fiberhome.com.cn ¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡2004-03-11 _______________________________________________ http://www.opencores.org/mailman/listinfo/ethmac




about SetInvalidSymbol
by Unknown on Mar 11, 2004
Not available!
Hi igor,


Is this core takes care of clock frequency variation i.e. 25MHz +/- 100ppm ???

By chance if u receive extra byte, Is that frame is discarded???


Karthik D.





"Igor Mohor(opencores)" igorm@opencores.org> 03/11/04 02:03PM >>>

We are talking here about invalid symbol, not invalid packet.

Invalid symbol is when only half of byte (one nibble) is received.
It is reported by the PHY by sending 4'he.


Regards,
Igor



-----Original Message----- From: ethmac-bounces@opencores.org
[mailto:ethmac-bounces@opencores.org]
On Behalf Of ybhuang
Sent: Thursday, March 11, 2004 7:32 AM
To: List about open source Ethernet MAC core
Subject: [ethmac] about SetInvalidSymbol

Hi,
I find in module eth_macstatus.v ,we define

assign SetInvalidSymbol = MRxDV & MRxErr & MRxD[3:0] == 4'he;

but in IEEE Std 802.3, 2000 Edition ,it suggest if MRXDV assert and
MRXERR assert ,
the packet is invalid. why in this module ,you must add " MRxD[3:0]

==
4'he"





======= 2004-03-01 18:28:00 ???????:=======

>Hi,
>
> I'm in the process of writing a HDLC mapper and I looked into the

mailing
>list and found the discussion attached below.
>
> My question is, if you do not know what length the packet is in

advance, how
>do you solve the initialization problem ? I do not wish to buffer the

entire
>packet before I can calculate the CRC on it.
>
> Is there a solution to that, or am I completly on the wrong track ?
>
> Thanks,
> Erez.
>
>Attached msg below:
>
>
> Mathew Hi,
>
> The idea behind unaligned width is that indeed as you understood

we
>pad with "enough" "same pattern" to fill and align the width.
>
>now that we have the padding you data is align so this part is

solved.
>
>the problem you need now to solve is that you don;t really want to

calculate
>the crc of the padding as this is just for alignment purpose.
>
>and so the solution is that you do "back calculation" of the crc and

find
>the initial crc value that once tha padding pass through it you get

all
"1"
>and so your crc machine caluclate in reality only the data.
>
>this way you get calculation of only the real data as well as your

data
is
>align.
>
>I'm off for almost 4 weeks, so if you have more question I'm sure

other
can
>also help and if not once I'm back I will try to answer what still is

not
>clear. > >good luck and have fun with your crc machines. > > Illan > >_______________________________________________ >http://www.opencores.org/mailman/listinfo/ethmac
= = = = = = = = = = = = = = = = = = = = ? ?! ybhuang ybhuang@fiberhome.com.cn 2004-03-11 _______________________________________________ http://www.opencores.org/mailman/listinfo/ethmac
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