Re[2]: [cc65] Atari file i/o functions

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From: groepaz (groepaz_at_gmx.net)
Date: 2002-04-24 13:54:58


Hello Ullrich,

Wednesday, April 24, 2002, 1:50:10 PM, you wrote:


UvB> On Wed, Apr 24, 2002 at 01:38:39PM +0200, Adam Dunkels wrote:
>> I can only agree with groepaz - cool! This would make it easier to support
>> dynamic applications in uIP as well!

UvB> Yes. But as I said before, writing modules in C has some overhead. The reason
UvB> for this is that the loader does not use the symbols from the o65 file for
UvB> runtime linking, because of the overhead. By using import/export name tables,
UvB> it would be possible to link a C module so that it uses the runtime routines
>>from the main module. But this would require a large name table in the
UvB> application, because the application must know at runtime, which functions
>>from the runtime library are available and at which address. Both operating
UvB> systems using the o65 format (OS/A65 and Lunix) don't do that for the same
UvB> reason (too much overhead).

UvB> Instead of using dynamic linking by name, modules are supposed to have a jump
UvB> table at the start address of the code segment - I think we can live with
UvB> that, especially for drivers, which will have a fixed set of API functions
UvB> anyway.

UvB> So a loaded module written in C must contain all the runtime stuff by itself,
UvB> even if the same routines are also linked to the main program. This will lead
UvB> to some overhead (how much this is exactly depends on the module in question).

aint going to be THAT much of a problem though i'd guess... like you
said, anything that can be considered "driver" wouldnt suffer much,
and anything else would be a special-case anyway (somehow ;=P)


-- 
Best regards,
 groepaz                            mailto:groepaz_at_gmx.net


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