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Re: Different prerequisites for ProDOS 8 MLI API

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John Brooks wrote:
> On Monday, February 6, 2017 at 5:44:59 AM UTC-8, Benoit0123 wrote:
>> Hi all,
>> I am in the process of developing a ProDOS 8 utility, and am getting
>> getting
>> some weird results in some cases.
>> I got a look at two reference manuals available online, that is:
>> The ProDOS 8 TRM, and
>> Beneath Apple ProDOS by Don Worth and Peter Lechner.
>> 
>> The requirement being on the io_buffer address that should be passed to
>> the
>> OPEN MLI call.
>> The PRM states that the io_buffer address should point to a non allocated
>> 1024 bytes buffer beginning at a page address ("$XY00" address)
>> The Beneath Apple ProDOS states that the io_buffer address should point
>> to a
>> page with the same properties as stated above but in addition that the
>> page
>> number be *even* (I understand: divisible by 2). One block for the index
>> data storage, and the other block for the data storage itself.
>> 
>> For the time being the buffer setup start @ address $B900 and ends @
>> address
>> $BCFF and I am getting some weird result but not always.
>> My asking is: do you know from your experience if the requirement that
>> the
>> page # for specifying the buffer begin be even is a valid requirement or
>> not.
>> 
>> The buffers setup by BI (BASIC.SYSTEM) start @ adress $9600, $9200, ...
>> so
>> are always compliant with the stricter constraints quoted above.
>> 
>> Thank your for any information on this,
>> 
>> Anyway tonight I will reorganize my code and give it a try once I am back
>> @
>> home.
>> 
>> Regards,
>> Benoît
>> 
>> 
>> -- 
>> Growing old is mandatory..
>> growing up is optional..
>> But the other way round is as true.
> 
> In ProDOS 2.4.1, the 1KB 'open file' buffers only need to be page aligned.
> Perhaps an earlier version of ProDOS required even page alignment, but I
> see no such requirement in 2.4.1.
> 
> What kind of 'weird results' are you seeing when the buffer starts on an
> odd page?
> 
> -JB
> @JBrooksBSI
>
Hereby I can confirm that by embedding the MLI call between two code
segments LDA $49 PHA LDA $48 PHA and PLA STA $48 PLA STA $49, the issue is
solved, that is ProDOS MLI is using page zero locations $48 and $49 (as
quoted in paragraph 3.3.1) and not restoring them once the call is complete.
Just hoping that none of the page zero locations $40-$4E are to be made
persistent between two MLI calls by ProDOS kernel.
Regards,
Benoît



-- 
Growing old is mandatory..
growing up is optional..
But the other way round is as true.

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Different prerequisites for ProDOS 8 MLI API Benoit0123 <bgilon@free.fr> - 2017-02-06 13:43 +0000
  Re: Different prerequisites for ProDOS 8 MLI API John Brooks <jbrooks@blueshiftinc.com> - 2017-02-06 08:09 -0800
    Re: Different prerequisites for ProDOS 8 MLI API Benoit0123 <bgilon@free.fr> - 2017-02-12 10:35 +0000
    Re: Different prerequisites for ProDOS 8 MLI API Benoit0123 <bgilon@free.fr> - 2017-02-12 10:52 +0000
    Re: Different prerequisites for ProDOS 8 MLI API Benoit0123 <bgilon@free.fr> - 2017-02-12 14:02 +0000
      Re: Different prerequisites for ProDOS 8 MLI API John Brooks <jbrooks@blueshiftinc.com> - 2017-02-12 13:28 -0800

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