CODEWITHSUNDEEP
assemblycpu-registersmotorola68000
J Tarantino
J Tarantino

Reputation: 75

Output is being recorded with garbage assembly Motorola 68K

I am having problem getting rid of the trailing trash in memory when logging my output.

I have a number n in my D1 and another one in D2.

Whenever I log them, the appear like this:

1-20012

but I just want the 1-2

I would just like to know how would I be able to select certain bytes of my Data Registers and put them in memory (in a ds.b declared storage with label result with size of 40 bytes).

Say, if I store the 1 in the starting address of my label "result" ($0000 2450), the '1' would only take up 1 byte, so will the '-' sign, as well as the '2'. So these contents would be stored in the range $0000 2450 - $0000 2452. The thing is that the following byte addresses contain garbage from previous operations and I am not allowed to clear them manually. I need to develop a method to clear them during runtime.

How would I ignore the following garbage bytes that are logged all together with my '1-2' print?

Thank you for your help!

Upvotes: 0

Views: 66

Answers (1)

Lars Brinkhoff
Lars Brinkhoff

Reputation: 14325

Like @Jester suggested, maybe you should terminate the string with a NUL character.

move.l #result,a0
move.b d1,(a0)+     ;Or maybe call a subroutine to convert from decimal?
move.b #'-',(a0)+
move.b d2,(a0)+
clr.b (a0)          ;Clear last byte.

Or if you want to use the number of bytes written:

move.b #result,a0
move.b d1,(a0)+
move.b #'-',(a0)+
move.b d2,(a0)+
sub.l #result,a0    ;A0 is now the number of bytes to log.

Upvotes: 1

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