Re: [avr-gcc-list] accessing carry bit

[Dave N6NZ]

John Regehr wrote:
> > microcontroller compilers support - the ability to write things like 
> > "if (CARRY) ..." can be a big win for some code.
>
> A killer app for exposing some of the condition code flags to C may be 
> that this facilitates very efficient integer over/under flow detection. 
> Integer overflows are the source of many nasty security holes.

I missed the earlier comments on this, but isn't getting to the 
condition codes a simple library of inline asm functions? Am I 
over-simplifying?

Of course, there are plenty of ways that could screw up optimization 
(unless optimization is oblivious, in which case optimizer code motion 
destroys the flag you are after.)

-dave