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Altera_Forum's avatar
Altera_Forum
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21 years ago

io.h vs normal data access

Hi there, Maybe a silly question... What is the purpose of the io.h headerfile? A memory addressable device can be referenced as follows: data = *(INT32U*) 0x200000; or using...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
21 years ago

I'm guessing that you have a data cache in your system, which is why you're seeing strange results with your first example. The second example maps onto the ldxio assembly functions which bypass the cache. For more information you should read Writing Device Drivers (page 7-4) in the Nios II Software Developer's Handbook (n2sw_nii5v2.pdf)