Bocco's adventures

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Re: Bocco's adventures

Post by iss » Thu Aug 15, 2019 11:03 pm

Sizes cc65 vs (osdk):

_playerUpdate 3549 (7581)
_emenyLeftRightUpdate 1414 (3247)
_addObjectInEngine 81 (!?!) (3070)
_animator 1055 (2066)
_enemyUpDownUpdate 828 (1712)
_printKeysScreen 610 (1512)
_input 206 (1376)
_addObject 538 (1216)

Attached are sym+map files.
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Re: Bocco's adventures

Post by Dbug » Fri Aug 16, 2019 5:15 pm

That's a crazy size reduction.

Is it somewhat possible to compile CC65 to assembler source code so I can compare the results with what LCC is generating?
I think Fabrice would be interested :)

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Re: Bocco's adventures

Post by Chema » Sat Aug 17, 2019 8:28 pm

Crazy and quite unexplainable, if you ask me. I can't see how this can happen, unless everything is implemented as subroutines, with the consequent waste of time.

Other big cuts to code size could be achieved by adding constraints to the compiler. If you don't allow recursion or limit the number or type of the parameters in functions, but I doubt that is the case here.

I am curious indeed :)

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Re: Bocco's adventures

Post by retroric » Sun Aug 18, 2019 6:24 pm


If you look at the code on GitHub, you can see there are quite a lot of functions, many of them taking many parameters, even including "int" parameters for some of them... Yet, cc65 seems to generate code that is both quite compact and fast. On the latter point if would be interesting as well to compare the relative speeds of the game compiled with cc65 and OSDK...

Now, if you look at functions like animator() (in src/engine.c), where the generated code is twice as big for OSDK, you see it is composed mainly of conditionals, dereferencing arrays with pointers, integer computations, and only 4 calls to the same "printBG()' functions, so it looks like the difference between cc65 and lcc65 (OSDK) may not necessarily be in the calling of functions, but maybe rather in the way conditionals, tests, pointer operations and arithmetics is implemented.

Obviously, to be able to see exactly where cc65 is more efficient than lcc65 we would need to be able to compare generated assembly codes, as DBug pointed out..
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