Malloc sans Free

Nope... It''s up to you to do that. You misread the source code I''m sure because Carmack doesn''t make mistakes like that. Keep doing what you''re doing now.

BTW, it''s better to use new and delete if you''re not doing strict C because they are typesafe, init classes (if you use them), etc.

1. Any serious OS will free the memory used by a program once it''s killed, either by a normal exit or a crash.

2. In practice however, it doesn''t always work that well. NT based versions of Windows (NT/2k/XP) are ok with it but I''ve noticed several times that 9x based versions sometimes don''t properly release the memory, and you have to reboot your system once in a while. Since it''s pretty random and this can even append when you call free(), there''s not much you can do about it.

3. This apply to new/delete too, since they call malloc/free. However, although your memory will be freed, your object destructors won''t be automatically called. If you''re just freeing memory inside them it''s not that much of a problem (since it will be freed anyway), but it could be troublesome if you also do other things like writting to a log file in your destructor.

to prosper: yes, this is what I assumed but I just wanted to make sure and get some further info. thnks.

to heretic: hath I offended the god they call Carmack the Great?? the error function prints out a message then calls exit(1). this happens many times after allocation of memory. Misreading? I doubt it...

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Original post by Prosper/LOADED
2. In practice however, it doesn''t always work that well. NT based versions of Windows (NT/2k/XP) are ok with it but I''ve noticed several times that 9x based versions sometimes don''t properly release the memory, and you have to reboot your system once in a while. Since it''s pretty random and this can even append when you call free(), there''s not much you can do about it.

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This has to do with other flaws in the OS, and not malloc/free/new/delete.

You don''t need to worry about explicitly freeing malloc()''d memory if you''re exiting immediately.

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Original post by C-Junkie
You don''t need to worry about explicitly freeing malloc()''d memory if you''re exiting immediately.

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Which is why Carmack doesn''t, the exit points for errors are probably not where he can actually free() all the memory allocated, and he''s exiting with a non-zero exit code anyway, indicating failure.

Any memory allocated from the process heaps (e.g. using malloc, new, HeapAlloc) will be released automatically by the OS becuase it''s all virtual memory and only has relevence to your process - all pages for your process will automatically be wiped out.

However there ARE other types of allocations that DO have a system wide effect that you should be careful about:

- handles & other objects from system DLLs. A very common bug people do is not restoring the default pen/brush etc when they''ve been doing GDI stuff - the internal refcounting means the memory and handle stays allocated inside the GDI. Under Windows 9x if you do that too much the machine grinds to a halt and you get a blue screen or white Windows 3.1 style error box informing you that the system is low on resources.

- kernel memory (i.e. real blocks of memory) - certain functions that use hardware cause the drivers for that hardware to do things like allocate kernel memory buffers (e.g. you can only DMA with real addresses and true contiguous memory so drivers have to allocate physical memory).

- external resources. For example DirectDraw surfaces etc (although in that case, Ddhelp tries to tidy up, and the driver resets the state when a new context is created).

--
Simon O''Connor
Creative Asylum Ltd
www.creative-asylum.com

not to change the subject or anything, but this is sorta related...

out of curiosity, does anyone know (or is there a correct way) to reset the resolution after your game/app has changed the res to something other than the desktop setting? one thing i hate, esp. when done by commercial-level games, is when i have to re-stretch the wallpaper after i''ve exitted a game.

maybe it''s something that i''m doing or some setting i have enabled/disabled, but as an example i *always* have to re-stretch the wallpaper after quitting command and conquer generals.

carmack isn''t the only programmer at id

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Original post by petewood
carmack isn''t the only programmer at id

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I really dubt that Carmack is that much of a *programmer* he''s
a genius alright, he solves problems and invent stuff noone
else could even have imagined, he probably writes the meanest
code ever, yup, he''s a god in that sense alright...

But ohh mhyyy ghoood he could also enter any obfuscation
contest with his regular source... and win!!!

Really as far as idols goes he''s one of greatest but
after trying to dechiper some of the stuff Id have released
Im quite confident that I wouldn''t want to try to maintain
or modify anything he have written...

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Original post by jorgander
not to change the subject or anything, but this is sorta related...

out of curiosity, does anyone know (or is there a correct way) to reset the resolution after your game/app has changed the res to something other than the desktop setting? one thing i hate, esp. when done by commercial-level games, is when i have to re-stretch the wallpaper after i''ve exitted a game.

maybe it''s something that i''m doing or some setting i have enabled/disabled, but as an example i *always* have to re-stretch the wallpaper after quitting command and conquer generals.

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That sounds like the game in question using the desktop HWND as their parent (or even worse, main) window. i.e. a lame coding practice.

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I really dubt that Carmack is that much of a *programmer* he''s
a genius alright, he solves problems and invent stuff noone
else could even have imagined, he probably writes the meanest
code ever, yup, he''s a god in that sense alright...

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Not to sound too much of a cynic, but many of the techniques Carmack uses in his code are standard techniques / techniques invented by someone else that wrongly get attributed to him.

A recent example seems to be his fast inverse square root, which is a standard Newton Raphson method with a floating point hack apparently invented by some guy at NVidia.

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This is the tale of a Northern Soul, looking to find his way back home

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But ohh mhyyy ghoood he could also enter any obfuscation
contest with his regular source... and win!!!

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agreed :D

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Original post by Anonymous Poster
Windows is supposed to free all allocated memory on the heap and all the rest too. It doesn''t, we all now that.

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We do?

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A c++ memory q.
Allocataing a big hunch of memory with malloc and the handle the dynamic memory allocations yourself by taking parts of this pool can give large performance increases while using c. Is it possible to do this in c++?

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It''s certainly possible to try ... whether or not you actually see any performance increase depends on your code and your usage scenarions. For starters, you should have a look at custom allocators, overloaded new/delete operators, and placement new.