[Coco] A bug in Basic09/RunB

[Gene Heskett]

On Sunday 06 December 2009, Wayne Campbell wrote:
>Gene,
>
>As I said before, I can't be certain this problem didn't exist before the
> modifications. For all the work I did developing DCom, I don't recall
> looking that deeply into what was being passed. I assumed it would be
> correct.
>
>Therefore, the bug may go all the way back to Basic09 1.00.00 and was never
> caught. It is possible.
>
>Wayne
>
>
>
>
>________________________________
>From: Gene Heskett <gene.heskett at verizon.net>
>To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
>Sent: Sun, December 6, 2009 7:28:51 PM
>Subject: Re: [Coco] A bug in Basic09/RunB
>
>On Sunday 06 December 2009, Wayne Campbell wrote:
>>James,
>>
>>I would love to do that, but I have had a problem with booting the
>> original OS-9 Level 2. I get a black screen with a magenta cursor. I can
>> see that the system is booted and the startup file is being displayed by
>> the movements of the cursor. I can set date and time, though I can't see
>> what I'm typing. Using display commands from the command line yields no
>> change. Until I can fix that, I can't test anything.
>>
>>In addition to the previous post, there is a third bug. I had almost
>> entirely forgotten it. It also involves parameter passing, but deals with
>> passing fields of records. You can pass one level deep:
>>
>>RUN GFX2("FCOL",col.bl)
>>
>>but you cannot pass:
>>
>>RUN GFX2("FCOL",col.fg.bl)
>>
>>Basic09 does not return a compiler error, but the value passed during
>> execution is incorrect.
>>
>>Since all 3 of these bugs are related to parameter passing, I think the
>> routines dealing with establishment of the pointers in the list should be
>> looked at first, and then the parameter counter for receiving parameters
>> into called procedures to see why it's miscounting them.
>>
>>Wayne
>>
>>
>>
>>________________________________
>>From: "jdaggett at gate.net" <jdaggett at gate.net>
>>To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
>>Sent: Sun, December 6, 2009 5:56:32 PM
>>Subject: Re: [Coco] A bug in Basic09/RunB
>>
>>Wayne
>>
>>One way of determing whether the original Basic09 has this bug or was
>> introduced in later modifications is to run you tests on the stock
>> version Basic09. Instead of booting with the newer NitrOS9, just boot up
>> your system with the orignal OS9 Level II disks and with Basic09
>>
>>just my thoughts
>>james
>>
>>On 6 Dec 2009 at 17:49, Wayne Campbell wrote:
>>> When I first learned Basic09, I did not possess the knoweledge and
>>> experience that I now have. There were many things that were overlooked
>>> in DCom, simply because I did not understand the function. Now, I know
>>> more about the function.
>>>
>>> I believe I have found a bug in Basic09. With all of the modifications
>>> that were made to Basic09 between 2002 and 2006, I cannot be certain
>>> that this bug did not exist prior to the modifications. However, if
>>> experience is any guide, it may well have gotten broken during the
>>> modification process and was never discovered.
>>>
>>> The bug is in the way parameters are passed to called procedures. First,
>>> any simple variable type (other than boolean) can be passed by value
>>> using +0 on the byte, int and real variables, and +"" on strings. To
>>> pass a boolean value, use TRUE or FALSE.
>>>
>>> Second, as long as the receiving variable is of the correct size, it
>>> doesn't matter what type or order you specify the parameter list in. It
>>> just has to match the size.
>>>
>>> The first bug occurs when you pass a byte by value:
>>>
>>> a:BYTE
>>> a:=1
>>> RUN myProc(a+0)
>>> END
>>>
>>> PROCEDURE myProc
>>> PARAM a:BYTE
>>>
>>> PRINT a
>>>
>>> END
>>>
>>> The result should be
>>>
>>> 1
>>>
>>> Instead,, it is
>>>
>>> 0
>>>
>>> The wrong byte is being retrieved. All BYTE variables are expanded into
>>> INTEGERs before being processed. In this case, the first byte of the
>>> integer is being read, not the second. I can never remember which order
>>> they are in, so I'm not certain which one is LSB and which one is MSB.
>>> To be clear:
>>>
>>>   +---+---+
>>>
>>>   | 1 | 2 |
>>>
>>>   +---+---+
>>>
>>> Byte 1 is being read, when byte 2 should be being read.
>>>
>>> The second bug occurs when you pass multiple variables into a single
>>> variable. Based on the fact that it works correctly, under the following
>>> conditions, on the first 2 elements of the receiving array, it should be
>>> working correctly for all of the parameters needed to equal its size.
>>> The test procedure passed 3 INTEGER variables into 1 3-element INTEGER
>>> array.
>>>
>>> PROCEDURE testParams
>>> DIM a,b,c:INTEGER
>>> a:=1 \b:=2 \c:=3
>>> RUN recPars(a,b,c)
>>> END
>>>
>>> PROCEDURE recPars
>>> DIM cntr:INTEGER
>>> PARAM d(3):INTEGER
>>>
>>> FOR cntr:=1 TO 3
>>> PRINT d(cntr)
>>> NEXT cntr
>>> END
>>>
>>> Results:
>>>
>>> 1
>>> 2
>>> 56 (Parameter Error)
>>>
>>> In addition, I added a fourth parameter, a second reference to a, and a
>>> 4th element to d. The error occurred in the same position in the array
>>> as before. Therefore, the accumulator that is supposed to count the
>>> parameter sizes is exiting before the final parameters are being
>>> processed.
>>>
>>> I do not know enough about assembly language to track down these bugs.
>>> Maybe someday, not not any time soon. If someone on this list wants to
>>> see if they can figure it out, the source to the modified Basic09 and
>>> RunB are on sourceforge.
>>>
>>> http://nitros9.cvs.sourceforge.net/viewvc/nitros9/nitros9/3rdparty/packa
>>>g es/basic09/?sortdir=down
>>>
>>> I'll report anything else I find out as I go.
>>>
>>> Wayne
>
>Wayne;  AFAIK, only 1 byte has been changed is both basic09 and in runb
> since the original distribution by Tandy.  I don't have access to it at
> the moment but a cmp should spit out the diff.
>
>If this is no longer true, then Robert or Boisy please pipe up and clarify.
>
I have an icon editor that passes params by the trainload, and I don't recall 
that I had any problems that resemble what you have described.  OTOH, since 
the serial mouse driver was removed from co80 or cc3io I haven't been able to 
use the mouse as I had before, and I've not had the time to run it down..  
Only the left mouse button works out of 3 now, and years ago all 3 buttons 
worked.  Button data is getting to the mouse packet, but is seemingly being 
ignored by gshell & multivue now.

-- 
Cheers, Gene
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