[Oberon] Low-Level Tricks - was: Volatile variables in Oberon

[Skulski, Wojciech]

Bernhard:

  thank you for the pointer to this code. I would not suspect it was a good source for answering my FPGA questions. You need to know the answer in order to appreciate this example contains the answer ;-)

It is also interesting to see that the TCP/IP was coded in Oberon. In principle it is not difficult to design an FPGA board using the AX88180 (in order to avoid paying big bucks to Xilinx for their firmware MAC). This chip has a decent gigabit performance. The TCP/IP code base seems to exist.

Wojtek

Wojtek

________________________________________
From: Treutwein Bernhard [Bernhard.Treutwein at Verwaltung.Uni-Muenchen.DE]
Sent: Tuesday, August 2, 2016 3:06 AM
To: 'ETH Oberon and related systems'
Subject: Low-Level Tricks - was: [Oberon] Volatile variables in Oberon

Hi Wojtek,

> I quickly scanned the Project Oberon from the NW website looking for
> implementation hints which you outlined. I did not find this discussion

I don't know if these dirty tricks are written down somewhere, but you
see them in many low-level driver modules, e.g. the 3Com EtherLink XL
driver, see line 59, 74 and 520ff :
trac.inf.ethz.ch/trac/lecturers/a2/browser/trunk/source/Ethernet3Com90x.Mod
--
  Bernhard

>-----Original Message-----
>From: Skulski, Wojciech [mailto:skulski at pas.rochester.edu]
>Sent: Tuesday, August 02, 2016 7:34 AM
>To: Treutwein Bernhard; 'ETH Oberon and related systems'
>Cc: joerg.straube at iaeth.ch
>Subject: RE: [Oberon] Volatile variables in Oberon
>
>Joerg and Bernhard:
>
>thank you for the very helpful discussion. I duly saved your e-mails for future
>reference. I would not decipher these tricks from the SYSTEM description in
>the language report. Your insight was very helpful.
>
>I quickly scanned the Project Oberon from the NW website looking for
>implementation hints which you outlined. I did not find this discussion
>anywhere (excuse me if I skipped it). The NW book does not go into this level
>of implementation detail. I would be great if a short app note was available
>illustrating HW access via volatile memory structures using your examples.
>
>Thank you for your help.
>
>Wojtek
>
>________________________________________
>From: Treutwein Bernhard [Bernhard.Treutwein at Verwaltung.Uni-
>Muenchen.DE]
>Sent: Monday, August 1, 2016 6:46 AM
>To: 'ETH Oberon and related systems'
>Subject: RE: [Oberon] Volatile variables in Oberon
>
>Hi Wojciech,
>
>> a high level Oberon array carries the hidden memory tag.
>
>Yes, but as far as I know all recent implementation have the hidden
>type tags at negative address offsets. You must know these
>implementation details and you are absolutely correct that these are
>dirty tricks. Therefore the IMPORT SYSTEM is essential, but I think these
>tricks are essential for hardware programming.
>
>--
>  Bernhard