[Oberon] Fw: FPGA - Bitmaps.Mod

[Tomas Kral]

Hi,

I am not getting much response re below forward.
I try now to formulate my question better.

[a]
I realised I cannot use this construct under V07
SYSTEM.NEW(addr, size);
Correct?

[b]
I tried to typecast it with SYSTEM.VAL
NEW(SYSTEM.VAL(addr, size));

But type cast is not allowed, possible reason as this would get
difficult job for the garbage collector?

Perhaps it is right ater all, I can use fix bitmap size flavours, 1/1
or 1/2 or 1/4 size of the left display viewer. As the purpose of a
bitmap is to show it in the viewer in the end anyway, clipped to a
visible area.  

[c]
That brings another question of SYSTEM function procedure
SYSTEM.VAL. Is it a type cast similar to Pascal ^((type) (variable))?
Need to understand better.

Many thanks
Tomas  


Begin forwarded message:

Date: Wed, 5 Apr 2017 17:59:27 +0200
From: Tomas Kral <thomas.kral at email.cz>
To: <oberon at lists.inf.ethz.ch>
Subject: Re: [Oberon] FPGA - Bitmaps.Mod


Hi Wojciech,

Yes, I agree.

But, I do not know, how to allocate dynamic structures on Oberon
V07. As an example I am looking into the `Pictures.Mod' code, taken from
ETH Oberon.

This dynamic allocation.
...
TYPE Addr = POINTER TO RECORD END;
     refr : Addr;
VAR size: LONGINT;
...
size := P.wth * P.height;
SYSTEM.NEW(P.refr, size+10);
P.address := SYSTEM.VAL(ADDRESS,P.refr);
NEW(P.bitmap);
Bitmaps.Define(P.bitmap,P.width,P.height,P.depth,P.address);
...

How I could allocate dynamically in Oberon07, NEW(v) allows for v as
variable?

Tomas 

On Wed, 5 Apr 2017 12:16:29 +0000
"Skulski, Wojciech" <skulski at pas.rochester.edu> wrote:

> > I am looking for a better way, as I believe the size needed can be
> > calculated from Width, Height of the bitmap.
> 
> Yes. The size of the display should not be fixed with inline numbers.
> I am thinking that a usable System can be deployed with 800x600
> display. In general, the size of the display can/ should be changed
> either on the fly or during compilation, which probably is not very
> difficult to implement in a simple design which the FPGA Oberon
> really is.
> 
> W.
> ________________________________________
> From: Oberon [oberon-bounces at lists.inf.ethz.ch] on behalf of Tomas
> Kral [thomas.kral at email.cz] Sent: Wednesday, April 5, 2017 5:26 AM
> To: Oberon at lists.inf.ethz.ch
> Subject: [Oberon] FPGA - Bitmaps.Mod
> 
> Hi,
> 
> As part of my exercise I have converted ETH `Bitmaps.Mod' to V07. It
> should be the basis for a bit map editor - `Paint.Mod' - next exercise
> of mine.
> 
> It is far from perfect, just made it to compile under V07, without
> much thoughts.
> 
> Few notes>>>
> 
> [a] Bitmaps.DisplayBlock* is just copied from Display.CopyBlock*
> with source and destination addresses modified as thus:
> 
> sa := B.address + u0*4 + sy*128; da := Display.Base + v0*4 + dy*128;
> 
> I am looking for a better idea, as I believe bitmap needs to be
> clipped to fit into a visible area of a target frame.
> 
> [b] New bitmap is allocated as a constant buffer
> CONST
>   BufSize = 10000H;
> ...
> BEGIN
>   NEW(buffer)
> END Bitmaps.
> 
> I am looking for a better way, as I believe the size needed can be
> calculated from Width, Height of the bitmap.
> 
> TYPE
>   Bitmap* = POINTER TO BitmapDesc;
>   BitmapDesc* = RECORD  (* cf. Display.DisplayBlock  *)
>     width*, height*, depth*: INTEGER;  (* offset 0, 2, 4 *)
>     wth*, address*: LONGINT;  (* offset 8, 12 *)
>     size: LONGINT
> END;
> 
> [c] Bitmaps are allocated as an array of CHAR's. Is it a good idea to
> use BYTE's instead?
> 
> P.S. I could enclose the whole module, but I am not sure if it is
> allowed by the list server.
> 
> Many thanks
> Tomas
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