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Forum: Coders. Tutorials 08 December 2018, 00:02
Replies: 111
Views: 29,686
Posted By ross
Yes, my first thought was for dbeq then i...

Yes, my first thought was for dbeq then i realized i had to keep a0 :D
Forum: Coders. Tutorials 07 December 2018, 22:36
Replies: 111
Views: 29,686
Posted By ross
Yes. I'm sorry but your code style is so...

Yes.


I'm sorry but your code style is so wrong for so much reasons (at least for the 68k architecture). Why mixing code/data and mess with stack and alignment?
Even understanding what you want...
Forum: Coders. Tutorials 07 December 2018, 10:29
Replies: 111
Views: 29,686
Posted By ross
Or if you care only about extract high bits you...

Or if you care only about extract high bits you can do:

move.w d0,-(sp)
move.b (sp)+,d0 *

16 cycles.

[* based on 68k stack auto-align property :)]
Forum: Coders. Tutorials 06 December 2018, 22:52
Replies: 111
Views: 29,686
Posted By ross
Shift and rotate it's not meant to be used...

Shift and rotate it's not meant to be used extensively with memory directly.
So an instruction like lsr <ea> can shift one bit only and the operand size is restricted to word (so you can think of it...
Forum: Coders. Tutorials 02 December 2018, 12:04
Replies: 111
Views: 29,686
Posted By ross
It is urgent that you understand how CIAs work. ...

It is urgent that you understand how CIAs work.
This chip is a 8-bits legacy and (like others CIA registers) at the $d location there are two memory cells, one read-only and one write-only.

It's...
Forum: Coders. Tutorials 02 December 2018, 11:39
Replies: 111
Views: 29,686
Posted By ross
:p Well, this is the reason why, if I do not...

:p

Well, this is the reason why, if I do not forget, I use brackets :D (and also a)
movea.l (level2_vector),a2

So to remember to myself that I want the memory content and all previous...
Forum: Coders. Tutorials 30 November 2018, 12:55
Replies: 111
Views: 29,686
Posted By ross
For some reason (that I don't remember precisely...

For some reason (that I don't remember precisely anymore) was a problem for me using a whole program in SuperState() mode.
Probably something to do with KS1.x dos.library (Tripos legacy..) that...
Forum: Coders. Tutorials 29 November 2018, 22:41
Replies: 111
Views: 29,686
Posted By ross
If you want a generic way that work on every 68k...

If you want a generic way that work on every 68k use the exec function SetSR
oldSR = SetSR(newSR, mask)
D0 D0 D1

To get the current SR:
currentSR = SetSR(0,0);
Or for the...
Forum: Coders. Tutorials 24 November 2018, 21:32
Replies: 111
Views: 29,686
Posted By ross
Or you can use copper to sync to DIW registers...

Or you can use copper to sync to DIW registers and gain COLOR0 for copper gradient.
A more advanced technique, used in some games masterpiece.


And always remember that you have to handle the...
Forum: Coders. Tutorials 24 November 2018, 21:16
Replies: 111
Views: 29,686
Posted By ross
ahem.. I dont want to be rude but too much to...

ahem.. I dont want to be rude but too much to correct here, better if you stop a bit and re-start studying 68k base properties.
And maybe forget what you have learned for other processors that does...
Forum: Coders. Tutorials 24 November 2018, 20:45
Replies: 111
Views: 29,686
Posted By ross
Yes, BASEREG is powerful, but be warned, a6 in...

Yes, BASEREG is powerful, but be warned, a6 in Amiga is used for library call.
Anyway define an address register used to access a heap with near displacement.

So you generally does lea haep,a4...
Forum: Coders. Tutorials 24 November 2018, 18:41
Replies: 111
Views: 29,686
Posted By ross
You have used -m68000. tab is a 32 bit address. ...

You have used -m68000. tab is a 32 bit address.
How this can be used for a 16 bit displacement?
Remove SECTION directive and use pc relative or better rethink your code :)
Forum: Coders. Tutorials 21 November 2018, 16:43
Replies: 111
Views: 29,686
Posted By ross
No. Color registers are R(4)G(4)B(4) so 4096...

No.
Color registers are R(4)G(4)B(4) so 4096 tone is the absolute maximum.
An halfbrite color is simply a R(x>>1)G(x>>1)B(x>>1) color, with the 'carry' bit discarded.


A register change every 8...
Forum: Coders. Tutorials 18 November 2018, 23:07
Replies: 111
Views: 29,686
Posted By ross
And this is perfectly accettable, in reality you...

And this is perfectly accettable, in reality you can also want to write your OS from scratch.
But if you want to write code in an active AmigaOS environment you need to know a bare minumum on how it...
Forum: Coders. Tutorials 18 November 2018, 14:44
Replies: 111
Views: 29,686
Posted By ross
Why you assumed that at $20000 and up you have...

Why you assumed that at $20000 and up you have free and usable memory locations?
In Amiga there is only ONE fixed memory location: ($4 aka execbase).
Everything else is dynamic, derive from...
Forum: Coders. Tutorials 17 November 2018, 20:23
Replies: 111
Views: 29,686
Posted By ross
You need to properly disable sprites.

You need to properly disable sprites.
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