The Sinclair QL Forum

t0nyt wrote:Thanks Tofro, but I still don't understand some of it - sorry

NormanDunbar wrote: Fri Feb 23, 2024 12:47 pm

t0nyt wrote:Thanks Tofro, but I still don't understand some of it - sorry

The following might help you out with regard to the QDOS/SMSQ internals of jobs etc.

My somewhat irregular QL Assembly Language eMagazine: https://github.com/NormanDunbar/QLAssem ... e/releases there are 11 issues available for download.

My QL Assembly Language eBook. Originally serialised over numerous years in QL Today magazine. https://github.com/NormanDunbar/QLAssem ... tober-2020. It's been updated since the demise of said magazine and rejigged as an eBook.

Somewhere in amongst all that lot there should be details on how a QDOS/SMSQ job is set up and the registers involved and what they are used for,


HTH

And apologies if "granny already knows how to suck eggs"!

Cheers,
Norm.

t0nyt wrote: Fri Feb 23, 2024 4:17 pm As a quick and dirty test I put code in the timerTick routine to change the screen mode

As hoped the screen mode continually get's reset, which to my mind means the routine is being called as it should

My problem now is that I replaced that code with a line to add 1 to a counter location (which I initialised previously to 0) but whatever I try I can't use that counter in the main program loop to block for a time. It's like it's not incrementing.

The journey continues I guess

Could anyone confirm how many times a second the timerTick routine should be getting called please?

Many thanks

tofro wrote: Thu Feb 22, 2024 5:26 pm Don't use OFFSET.

Here's what I do:

• All of my program code goes into a SECTION code
• All of my data goes into a SECTION DATA

If you start a new section, the assembler re-sets all the addresses it generates to 0.
By setting a6 to the data space base adress at the beginning of the program and indexing by the labels in the data section, the assembler will manage the proper addresses:

Code: Select all

    SECTION data
a: DS.L    1
b: DS.L    1
c: DS.W   1
buffer:   ds.b 100

After this, the assembler will assign 0 to the a offset, 4 to b, 8 to c and 12 to buffer. In your code, do

Code: Select all

    SECTION code
    lea.l 0(a6,a4),a6     ; let a6 point to the bottom of the data space
    move.l #100,a(a6)    ; moves 100 to a6+a
    move.l #200,b(a6)   ;  same for b
    move.w #100-1,d0
loop:
    clr.b buffer(a6,d0.w)    ; clear the buffer
    dbra d0,loop
    

Thus, you don't really care where your variables are - they are always relative to a6, and where a6 points to was allocated by QDOS. You simply use the names.

If you write your code in multiple source files, the code that defines what's going on in your data space typically goes into an include file, that is INCLUDEd in all your code files.