QMAC Assembler

[Martin_Head]

I was trying to do something in QMAC, but I could not get it to work. I don't know if I am just doing something wrong, or if it's just not possible.

I want to assemble a program to create a ROM image. So it needs to be 16384 bytes long .

What I was trying to do, was to have a DS.B instruction at the end of the program to automatically pad out the assembly file to 16384 bytes.

I tried things like

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label ds.b 16384-label

and

Code: Select all

label equ *
      ds.b  16384-label

But whatever I tried, It would not assemble without error.

[Pr0f]

I've seen similar fill's in the Minerva source - not sure if that helps at all - at work so I don't have access to any notes / info to assist further.

[tofro]

I tried things like

Code: Select all

label ds.b 16384-label

and

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label equ *
      ds.b  16384-label

But whatever I tried, It would not assemble without error.

You are actually trying to get a reloctable program into the format of an absolute one. You may be better off starting a program targetted to ROM with an

Code: Select all

ORG 0

and end it with an

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ORG 16383
DC.b 0

and the linker will fill the space automatically. I have found that RORG works best for me, however (see below).

If you absolutely don't want to use the ORG directive, maybe something like

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          SECTION   code
          OFFSET 32767
codeend:  DS.B      0

might do the trick (OFFSET forces the next label to be at exactly that position in the relocatable section). The problem is that OFFSET doesn't allow you anything but allocation of space, so this might only work in data sections.

If that doesn't work, simply use the RORG directive to place a label at an exact offset to the beginning of a SECTION (I have found that works best for me):

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        RORG 32767
        dc.b 0

[Derek_Stewart]

I was trying to do something in QMAC, but I could not get it to work. I don't know if I am just doing something wrong, or if it's just not possible.

I want to assemble a program to create a ROM image. So it needs to be 16384 bytes long .

What I was trying to do, was to have a DS.B instruction at the end of the program to automatically pad out the assembly file to 16384 bytes.

I tried things like

Code: Select all

label ds.b 16384-label

and

Code: Select all

label equ *
      ds.b  16384-label

But whatever I tried, It would not assemble without error.

Hi Martin,

What is the error message?

[Mark Swift]

Hi Martin,

I've not checked the syntax, but I usually do something like this to pad to the nearest 16K...

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BASE:
	DC.B	'Put your code here',$A,$0

PAD16K:
	DCB.W ((0-(PAD16K-BASE))&$3FFF)/2,$4E71

[Martin_Head]

Thanks for the response's

Hi Martin,

What is the error message?

I can't remember exactly offhand. But I think it's something to do with relocatable objects.

I'm still fairly new to using QMAC (I'm used to the Talent/Quanta Assembler Workbench). I have not delved into things like linking or macros. I just assemble with the -NOLINK option.

The QMAC manual's not too helpful, if you don't know what you are doing in the first place.

Now I know it can be done, I will have a further play with the suggestions made. I think Mark Swifts solution looks like a good bet. I take it, that it just pads out with NOP's.

[Martin_Head]

I tried Mark's solution and it works fine.

I wondered why the calculation looked so complicated. So I tried to simplify it, but I got the errors back on trying to assemble it

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5016                          
5017 00 000022F4 31820000     cg_pat2a move.w   d2,(a0,d0.w)                  ;set instruction
5018                          
5019                          
5020                          
5021 00 000022F8 7000         cg_exit2 moveq    #$00,d0                       ;exit with no error
5022 00 000022FA 4E75                  rts
5023                          
5024                          
5025                          ; **************************************************
5026                          ; Uncomment the following when creating a ROM image
5027                          
5028                          ;prog_end dcb.w    ((0-(prog_end-start))&$3fff)/2,$4e71
5029                          
5030 00 000022FC              prog_end dcb.w    (16384-prog_end)/2,$4e71
                                                                |
****** ERROR 14 -- line 5030 -    0 - relocatable value not allowed here
5031                          ; **************************************************
5032                          
5033                                   
5034                                   end
****** TOTAL ERRORS    1 (line 5030)
**** TOTAL WARNINGS    0 (line    0)
       memory usage   71 kbytes

Both calculations give the same result - $1D04. I don't know what the first calculation doe's that's different. Unless the 16384 looks like some kind of forward reference.

[Silvester]

Isn't it because prog_end-start can be resolved immediately as an absolute number. But 16384-prog_end can't because prog_end position can't be resolved until linking/assembly? (16384 seen as fixed address, thus dcb.w size can't be resolved). QMAC manual page 29 Relocation factors: +1-1 (=0 absolute), +1 (+1 simple relocatable).

Edit: Just tried this and it also worked

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 prog_end   dcb.w    (16384-(prog_end-start))/2,$4e71

BTW for ROM shouldn't it be pad with $FF ?