Re: [Amforth-devel] .s on 1284p

[Marcin C. <sa...@sa...>]

On Sun, 29 Aug 2010, pito wrote:

> Marcin, when I do .s I see an address higher then 16383 (16557). So
> it is an indication for me something must be wrong there. Matthias
> sent the .s definition, from what I can see is he prints out the
> address (of RAM - I do assume - when talking data stack), and as I
> have shown the number is 16557.. So outside the RAM space. Maybe I
> am mistaken.. Just explain to me plz.. Assembly listing of what,
> please? P.

Please see m1264Pdef.inc file in your AVRASM directory:

---8<------------------------------
.equ    SRAM_START      = 0x0100
.equ    SRAM_SIZE       = 16384
.equ    RAMEND  = 0x40ff
.equ    XRAMEND = 0x0000
---8<------------------------------

RAM begins at $0100 and ends at $40ff.

So you have in your listing:

00002a ff 40         .dw rstackstart  ; USER_RP^M
00002c af 40         .dw stackstart   ; USER_SP0^M
00002e af 40         .dw stackstart   ; USER_SP^M

Your return stack starts at $40ff and grows down 
and your data stack starts at $40af and grows down.

Most ATmegas have stack at $0100, but some AVR
CPUs have it at $0040, $0060 or $0200.

My ATmega164P has RAM from $0100 until $08ff,
so my rstack starts at $08ff and my data stack
grows down from $08af.

Hope it helps!

--Marcin