In MATLAB, you can freely re-define pi and i. Setting pi=3D2 or 10 can make for some interesting debugging of code :) Sean On Tue, Aug 25, 2009 at 9:55 AM, M. Adam Davis wrote: > I was thinking something along those lines as well, but reduce the > probability of an error so it's less frequent and seemingly more > random: > > #define if(x) T0CON |=3D 0x80; if ((x) & (TMR0L & 0xF)) > > Would only have a 1 in 16 chance of affecting the if. =A0It wouldn't > mess up the timer unless they were turning the timer on and off inside > the program (usually it's either on or off for the entire program, if > it's off then they probably arent' using it, and if it's on our > statement doesn't affect that). > > Could go downhill from here, but of course the more we change each if > statement, the easier it'll be to see there's a big problem when > someone examines the compiler output. > > -Adam > > On Tue, Aug 25, 2009 at 9:18 AM, Philip Pemberton = wrote: >> Mark Rages wrote: >>> go for random failure: >>> >>> #define if(x) =A0if ((x) & PORTA) >> >> Or for even more fun, drive it off of TMR0: >> >> #define if(x) T0CON ^=3D 0x80; if ((x) & TMR0L) >> >> Or even: >> #define if(x) T0CON ^=3D 0x80; if ((x) & (TMR0L =3D=3D TMR0H)) >> >> Which toggles the timer on-state every time an 'if' statement rolls >> around. I'd file this under "absolutely evil" -- if the code makes use >> of TMR0 it's going to completely screw up the timing, if it doesn't... >> well... good luck figuring out what's going on, especially if TMR0L >> wasn't initialised to a defined value on boot (most 18Fs clear TMR0H to >> zero on any reset, but it's undefined on wakeup from SLEEP; TMR0L is >> undefined at any reset or wakeup). >> >> -- >> Phil. >> piclist@philpem.me.uk >> http://www.philpem.me.uk/ >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- = http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist