Re: Error in NatLib_InstallImmutableStateBlock??

Jonathan Sharret wrote:

>Hi,
>
>I think I found an error, or at least misleading information in the
>description for NatLib_InstallImmutableStateBlock.  In Native_API it
>states that the method simply outputs a 0 in the accumulator if there
>was no error.  It makes no mention of changing anything.  However, I
>found that the 2 data pointers used as input are not preserved across
>the method call.  
>
These pointers should probably be preserved. We will either document 
this behavior better or preserve these pointers for the next TINI SDK 
release.

>I wrote code that writes into an immutable state block
>with a LibraryID supplied by the user as input to the native method.  If
>the state block doesn't already exist, the method is supposed to malloc
>it, install it and then write into it.  I couldn't understand why the
>1st time I would write it wouldn't work but the second and all
>subsequent times did work until I noticed that
>NatLib_InstallImmutableStateBlock is screwing with the data pointers.
>Here is the debug information I got out of the diagnostic port.
>
>Data pointers into the NatLib_InstallImmutableStateBlock method:
>
>DPTR1:1C9A4A
>DPTR2:1C9A67
>
>Data pointers after the NatLib_InstallImmutableStateBlock method:
>DPTR1:1C9A52
>DPTR2:1CCA7C
>
>In order to get the program to work properly, I had to preserve DPTR1
>across the method call myself since otherwise I'd be writing into the
>wrong memory location.
>
>Is this an error?  Or am I just supposed to know to preserve things
>myself?
>
>Another question, is there a list of registers that are safe and those
>that are unsafe to manipulate in a native method?
>
See Native_Methods.txt

>  I tried copying into
>DPTR3 as slack space instead of pushing and popping off the stack and
>got very bizarre results which leads me to think DPTR3 is off limits.
>  
>
 From Native_Methods.txt:
    The contents of the additional pair of DPTRs on the DS80C400
    must be preserved.

>Is this true?  What about other registers.
>
>Thanks,
>Jonathan Sharret
>
>TELEGRID Technologies, Inc.
>Email: j.sharret-vt2K7lilQm9Wk0Htik3J/[email protected]
>
>  
>


-- 
Thomas Chenot

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