There are some kext were ported from Linux to Darwin.
Then why ASLA is not?

I don't have much knowledge about system programming, somebody please explain to me.

Thanks

thats a hard question

i dnt think alsa will be ported that well to darwin ppl could try i searched on google it seems to be in beta stage

alsa is a very wide range audio system depending on different audio codecs than darwin

i think audio card support would go down if it was supported in darwin

linux is not MacOSX and driver porting is impossible.
We can only understand how the linux driver works and then write new MacOSX driver from initial.

As you know, almost the things they are having to patch AppleHDA are all about codec/layout/node/verb which is solved already in ALSA driver.
Anyways, any1 has info about VoodooHDA?