Simple code that won't work.

velocityxlrg · 2006-12-23 05:36

Can someone help me figure out why this short bit of code won't work?
I'm trying to display a variable on the TV screen, pause 3 seconds,
then start an assembly cog to add one to the variable, wait 3 more seconds,
and display the new value.

Paul Baker · 2006-12-23 05:53

Can you describe what does occur, do you see the first part?
Also a DAT long is an inline data assignment, change memory to res 1.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Christof Eb. · 2006-12-23 11:02

I am not shure, but I assume:
rdlong temp,memory
should be: mov temp,memory

because during startup of the new cog the location "memory" has been copied to this cog's ram and
mov memory,PAR
refers to the cog "memory" location and not to the main memory location.

Christof

Luis Digital · 2006-12-23 14:13

velocityxlrg said...
Can someone help me figure out why this short bit of code won't work?
I'm trying to display a variable on the TV screen, pause 3 seconds,
then start an assembly cog to add one to the variable, wait 3 more seconds,
and display the new value.

Assembly      mov       memory,PAR           
              rdlong    temp,memory
              add       temp,#1           
              wrlong    temp,memory
[b]             mov PAR, memory 'Maybe?[/b]

I do not have still [noparse]:([/noparse] my Propeller, so only is theory.

velocityxlrg · 2006-12-23 18:01

Paul Baker (Parallax) said...
Can you describe what does occur, do you see the first part?
Also a DAT long is an inline data assignment, change memory to res 1.

The TV screen displays the "variable=1234" then pauses 3 seconds.

The screen then gets some garbage characters then completely gets garbled up and quits.

I tried changing the DAT data assignment to memory RES 1, but that did not change anything.

velocityxlrg · 2006-12-23 18:07

Christof Eb. said...
I am not shure, but I assume:
rdlong temp,memory
should be: mov temp,memory

because during startup of the new cog the location "memory" has been copied to this cog's ram and
mov memory,PAR
refers to the cog "memory" location and not to the main memory location.

Christof

I'm quite sure that when you "mov memory,PAR" you are only copying the main memory location to
the new cog's variable called memory. So to read the value store in the main memory at that location
you need to rdlong temp,memory which transfers a copy of the main memory content to the cog's
memory variable called temp. But I could be wrong - my code doesn't work!

Mike Green · 2006-12-23 18:27

DAT
                    org       0
Assembly      rdlong    temp,PAR  ' You're only referencing one location,
                    add       temp,#1    ' so you can use PAR directly and keep
                    wrlong    temp,PAR ' things simpler.
                    cogid      temp        ' Always best to stop the program when
                    cogstop  temp        ' it's done

temp            res 1

Another thing I noticed. The TV base pin is 25. This needs to be a multiple of 4
as I understand it.

velocityxlrg · 2006-12-23 18:35

Mike Green said...

DAT
                    org       0
Assembly      rdlong    temp,PAR  ' You're only referencing one location,
                    add       temp,#1    ' so you can use PAR directly and keep
                    wrlong    temp,PAR ' things simpler.
                    cogid      temp        ' Always best to stop the program when
                    cogstop  temp        ' it's done

temp            res 1

Another thing I noticed. The TV base pin is 25. This needs to be a multiple of 4
as I understand it.

Good catch Mr. Green. The problem was that the cog wasn't stopping and must of been stomping
all over the memory. As far as I can tell, the TV base pin doesn't care about being a
multiple of 4 - I've had it in a number of places on my breadboard.

Luis Digital · 2006-12-23 21:00

Now I understand "memory" and "PAR" are Pointers.

Then the problem was that in Spin a program finalizes when there is not more lines, but in ASM the counter of the program (PC) continues the execution to the end ("executing" even data)?

Also:

:loop jmp #:loop

work?
Clearly it would be an expense to leave the Cog running.

Mike Green · 2006-12-23 21:24

Luis,
"memory" and "PAR" are memory locations which are used as pointers by the "RDxxx" and "WRxxx" instructions.

You're correct, ":loop jmp #:loop" would also work, but leave the cog running.
Mike

Simple code that won't work.

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