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Old 03 November 2011, 14:24   #1
mikro
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How do the non-i/o functions work?

Hello,

I hope this is a right place to ask, I'm curious about one thing. I understand the concept of WHDLoad, how it replaces disk access, fixes cache stuff etc but I can't understand how the other functions work when the OS is disabled.

FAQ/doc mentions memory allocation or disk access or some synchro functions (which can be NOP-ed) but what about the rest? Timers, palette setting, sound playback? I believe Amiga programmers have been very disciplined when it comes to system programming (i.e. not accessing hardware directly but calling OS functions instead) so ... how does this work in WHDLoad when no OS is present?

Every slave makes its own palette setting routines and replace the calls in the original binary? If so, what does this routine do? I can't believe it accesses HW directly, esp. when it is supposed to work on variety of AmigaOS flavors...

Can someone explain? Thanks in advance!
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Old 03 November 2011, 14:50   #2
S0ulA55a551n
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Nearly all games on the Amiga disable the OS and bang the hardware directly
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Old 03 November 2011, 15:21   #3
StingRay
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Quote:
Originally Posted by mikro View Post
Timers, palette setting, sound playback?
Almost all games have their own custom routines for these tasks.

Quote:
Originally Posted by mikro View Post
how does this work in WHDLoad when no OS is present?
If the game uses only a few system routines you can emulate them, i.e. recode them without using the OS. If there are lots of OS routines used, WHDLoad has its own "KickEmu" routines which emulate the OS.

Last edited by StingRay; 03 November 2011 at 15:38. Reason: typo
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Old 03 November 2011, 15:33   #4
mikro
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Ah, that's interesting. In Atari world, that's normal thing but since I've seen source code of some recent Amiga demos, I thought it's common practice for games since the beginning. Thanks for explanation!
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