[Asterisk-Dev] Patching flags to bitfield structs

[Andrew Thompson]

Kevin P. Fleming wrote:
> Andrew Thompson wrote:
> 
>> What they are talking about now, is putting all the variables that the 
>> flags were were supposed to represent back in as defined variables, 
>> but this time, using the variablename:X format to specify how many 
>> bits the variable should take up.
> 
> 
> Exactly. Let the compiler figure out how to combine 11 variables that 
> take up one or two bits each into storage in the struct, and let it 
> build the code to access them however it feels it best (as opposed to 
> using the existing macros). Where this really shines is in the cases 
> where have "flags" that have more than two values and require two bits 
> or more; the existing code for manipulating those is non-intuitive and 
> somewhat error-prone. Letting the compiler handle it would solve that 
> problem completely.

Please forgive the newbie question, but, what happens if you overflow 
one of these bitpacked/storage optimized/colon number variables?

Is the result undefined, or do they roll over like traditional 
variables? (I trust they won't screw up the next variable over in the 
structure, right?)

It would be up to the developer to make sure they don't assign a new 
value to a "flag" that is larger than it can store. I know this is a 
duh-like statement, but it's a lot more likely to occur, in this 
instance than with just "int use_new_doodad;".

-- 
Andrew Thompson
http://aktzero.com/
http://dev.asteriskdocs.org/