[Coco] os9/drivewire driver problems

[Aaron Wolfe]

Thanks for the response Boisy.  Your name is becoming a very common
sight on my screen as I look through the NitrOS9 and drivewire
modules.. is there anything you didn't write or improve? :)

I tried removing the A from the PULS but got the same results.  I am
failing to understand something about how the data is returned from
the DWSUB to the calling routine.  The reason I was pulling A, was I
thought the byte read by DWSUB,READ would be on the stack.. because I
thought I was putting a pointer to my stack in X prior to calling
DWSUB.  But I must be getting this wrong, either in concept or
implementation.  I apologize, my assembler skill was never very good
and I'm very rusty.  Trying to learn as I go here.

What is the proper way to get 1 byte of data from DWSUB into A?  I see
that when the rbfdw driver reads in a block, it puts a pointer to
PD.BUF in X prior to the read call, I am guessing this is where OS9
expects the block to be returned.

* Get 256 bytes of sector data
         ldx   5,s
         ldx   PD.BUF,x                 get buffer pointer into X
         ldy   #$0100
         jsr   3,u

when the clock2_dw gets time, I see:

         ldx   #D.Year
         ldy   #$0005
         jsr   3,u

So X is the constant D.Year, $53 from the coco OS9Defs file, I am
guessing this is writing the returned bytes directly into OS9's "whats
the current time" area?

Eventually I'd like to read a variable amount of data from the server,
but for now I am trying to just get one character at a time (the
server additions I've made have a buffer that can make this work sort
of OK).
So.. if I just want to get one byte into the A register..  can anyone
point out where my code or comments are wrong?  I'm sure I'm
misunderstanding something.  I've found what I think are some other
problems in my code, but still I get the same behavior, constant calls
back and forth to read and write with null results.
Current attempt:

Read    equ  *
        lda   #OP_SERREAD    ; put opcode for read in A
        pshs  a  ;  put A on stack
        leax  ,s  ;  put pointer to top of stack in X
        ldy   #$0001  ; put 1 in Y because we want to send 1 byte
        ldu   >D.DWSUB   ; put addr of DWSUB in U
        jsr   6,u  ;  call write routine, it should send one byte to
server asking for a character
*       puls  a   ;  was removing it, but I think I need to leave a
byte there so we have room for incoming byte and don't clobber other
contents?
        ldy   #$0001   ;  we want to read 1 byte back
        leax  ,s  ;  and put it on our stack, in place of A/the opcode
used in previous call
        jsr   3,u  ;  call DWSUB to read 1 byte
        puls  a,pc ; pull that byte and the pc off stack (pc now sends
us back to calling routine?)

I am guessing the address I'm supposed to return  to is already on the
stack when Read gets called?  Lots of example seem to pull PC of the
stack when they are ready to return but I haven't found where this is
documented so not entirely sure.

Well.. something is wrong with my code, any clues are much appreciated.
-Aaron



On Sun, Nov 8, 2009 at 8:37 AM, Boisy G. Pitre <boisy at tee-boy.com> wrote:
>
> On Nov 8, 2009, at 5:58 AM, Aaron Wolfe wrote:
>
>> First, please don't laugh, I am new and surely making many simple mistakes
>> here.
>> Second, I cannot say thank you enough to everyone who has made
>> NitrOS9, the toolshed and drivewire possible.  I'm very impressed by
>> how well the tools work.
>
> I think it's awesome that someone is taking the reigns and doing something
> like this.  Good going.
>
>> I am trying to add to drivewire the ability to act as a serial port
>> under NitrOS9.  I've managed to setup a build environment and create a
>> device descriptor and driver for the new device.  I added the op codes
>> and handling routines on the server side, etc.   I have write working,
>> but that's the easy part since the dw printer driver already did that
>> and I mostly just copied it.
>>
>> So, I can do things like:  LIST STARTUP > /T2
>> and everything works great.
>
> Good so far.
>
>> However, read is another story.  I can't seem to get anything working
>> properly and after several hours I am stumped.
>>
>> Here's what I think I've figured out about how dw works, I might have
>> some things wrong.
>> To read a character, I think I am supposed to put my opcode in A,
>> pointer for the incoming data in X (usually my stack, i think?), the
>> number of bytes to read in Y.
>> Then, jsr to the DWSUB and let the magic happen?  At least this is
>> what I think I've gleaned from the source of other modules.
>> According to the OS9 dev manual, the Read routine should return a
>> character in reg A.
>
> This all sounds correct.
>
>> So, my first attempt was:
>>
>> Read
>>       lda   #OP_SERREAD
>>       pshs  d
>>       leax  ,s
>>       ldy   #$0001
>>       ldu   >D.DWSUB
>>       jsr   6,u
>>      ldy   #$0001
>>      leax  ,s
>>      jsr   3,u
>>      puls  d,a,pc
>>
>> I may be doing stupid things here, I haven't done 6809 assembler in
>> many years.  I'm not sure what the 6, and 3, in the JSRs is for, it
>> seems like every write uses 6 and read uses 3 in the other modules.. ?
>
> the jsr 6,u says: "save the address of the next instruction on the stack,
> then obtain the two byte location 6 bytes from the U register and jump to
> that location."   The 6 jumps into the WRITE section of the DWSUB routine,
> and the 3 jumps into the READ routine.
>
>> This "works" in the sense that the server sees the call and sends back
>> a byte.  However, I've botched something because the process calling
>> read always gets a null character.  If I spawn a shell on /T2, it
>> reads and writes bytes constantly (I think it's echoing the character
>> it thinks I typed) but its all null chars.
>
> Your last line needs to read:  puls d,pc
>
> You don't want to pull A off the stack because you haven't pushed it on
> prior to the call.  I think you will find that it works after that.
>
> Note that you should be checking for a timeout error after the jsr 3,u and
> load B with an error if so, but get this working first.
>
>> So, I thought to test I would just:
>>
>> Read
>>       lda   #OP_SERREAD
>>       clrb
>>
>> (#OP_SERREAD is the character 'C').  I was hoping then that something
>> like LIST /T2 would give me a stream of Cs.  But instead I get Error
>> 208,  Illegal service request.
>
> Error #208 is an illegal service request.  I suspect you aren't implementing
> something in your getstat or setstat routine; I don't remember the exact
> issue here, and I'm not at my CoCo at the moment to test this out and
> remember.
>
> Try the fix above with your shell test and see if something happens.  Let us
> know.
>
>
>> Hopefully this makes some kind of sense, I'm sure I've done something
>> silly but if I make Read just put a constant in A and clear B (no
>> errors), shouldn't I get a character every time I call Read?
>
>
>> Thanks for any pointers
>> -Aaron
>>
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>> http://five.pairlist.net/mailman/listinfo/coco
>
>
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