sstack equ $30000
ustack equ $20000

org $10000
memd0 ds.b $a5


START ORG $1000
lea sstack,A7
andi.w #$dfff,SR
lea ustack,a7
jsr init
move.b #3,d0
jsr delay
move.b #3,d0
jsr ldelay

trap #15

org $2000
init move.b #0,D0
move.b d0,memd0
rts

delay sub.b #1,d0
bne delay
rts

ldelay move.b d0,memd0
move.b #3,d0
jsr delay
move.b memd0,d0
sub.b #1,d0
bne ldelay
rts

sub.b #1,d1

END START

This is a subroutine code. I need to draw a flow chart on this but I really have no idea how to do it. Can anyone help me please?

 

That's putting the carriage before the horse. One does not build a house and draw the plans after.

Flowchart comes before the code. Flowchart dictates the code. Not the other way around.

 

But this is my lab work. We are asked to make a flow chart. I don't really understand some of the parts and when I tried to ask, our lecturer doesn't want to answer them until the deadline is over. I need to submit it by tomorrow =(

 

Too bad, your instructor has it backwards and does not understand Top-Down design.

 

But can't anyone help me on this? I need it urgently...

 

So what would you learn from this exercise if someone did it for you?

 

After submitting it, I can ask the lecturer on all the parts I don't understand ...

 

So you just want the marks.

 

marks before understanding it. i don't have a choice.

 

Well, what have you learned or read about flow charts so far?

 

I know it started with initialize sstack, clear SR, initialize ustack, followed by subroutine, move 03 to d0 means delaying 3 seconds (not sure if this is right), then subroutine again and again move 03 to d0 and I'm stuck because subroutine started and before it ends, another subroutine started.

 

What do you mean by subroutine started and before it ends?

 

its like jsr,jsr then rts. normally it should be jsr, rts, jsr, rts right?

 

No. The rts is in the subroutine.

 

INSTRUCTION
lea sstack, A7
Andi.w #$dfff,SR
lea ustack, a7
jsr init
move.b #0,D0
move.b d0,memd0
rts
move.b #3,d0
jsr delay
sub.b #1,d0
bne delay
sub.b #1,d0
bne delay
sub.b #1,d0
bne delay
rts
move.b #3,d0
jsr delay
move.b d0,memd0
move.b #3,d0
jsr delay
sub.b #1,d0
bne delay
sub.b #1,d0
bne delay
sub.b #1,d0
bne delay
rts
move.b d0,memd0
sub.b #1,d0
bne 1delay
move.b d0,memd0
move.b #3,d0
jsr delay
sub.b #1,d0
bne delay
sub.b #1,d0
bne delay
sub.b #1,d0
bne delay
rts
move.b d0,memd0
sub.b #1,d0
bne delay
move.b d0,memd0
move.b #3,d0
jsr delay
sub.b #1,d0
bne delay
sub.b #1,d0
bne delay
sub.b #1,d0
bne delay
rts
move.b d0,memd0
sub.b #1,d0
bne 1delay
rts
trap #15

I dont understand the part highlighted in red.

 

No. You can't do that. You've mess up the original code.

 

but we were asked to trace the code this way ...

 

What do you mean by trace the code?

 

But this is my lab work. We are asked to make a flow chart. I don't really understand some of the parts and when I tried to ask, our lecturer doesn't want to answer them until the deadline is over. I need to submit it by tomorrow =(

He's a cobbler.

 

trace the code by jotting down the instructions, cycle, stack pointer, memory everytime we execute them