[ngc1977_81]

Hey everyone
I am doing some research on the R3000A instruction set for a college project, and I thought maybe somebody could help me with a question. Hopefully, one of the psx emu author's can answer it.
In the instruction set, the ADD and SUB instructions trap on integer overflow when they are adding/subtracting rs to rt. I was wondering if anyone could give an example of how that might be implemented in a language like C(basically a function that could test if a result has an arithmetic overflow). If anyone can help me out, it would be greatly appreciated
Thanks

 

[Ultragunner]

here's a text file with the info for your question, i think
hope it helps you though.........

 

[Xeven]

probably something like this? dunno squat btw..

temp = rs+rt;
if((rs^rt)>=0&&(rs^tmp)<0) exception_here();
else rd = temp;

its probably a crud of bull, i dunno dick.. hehe:evil::evil:


emu author's DONT KILL ME PLEASE.. :heh:

 

[PsYcHoJaK]

Download FPSE 0.08 Source Code. On the file 'CPU2.C' lookup for the 'ADD' opcode. You will see the exception there.

Btw, your college most probably rules. My university is all about 68000, old processor.

 

[CD]

Dude, the 68000 is great

 

[PsYcHoJaK]

Sure, no problem, but keep questions in general nature. Don't ever ask me for code, cause I've seen this before and I didn't like it at all.

Good Luck on the project,
pSyChOjAk

 

[PsYcHoJaK]

Heh, u seem alright. Anyway today I released the interpreter of PSinex on the public. I know its nothing special, but its always good to give info to the public. The public will appreciate your open source project a lot, believe me. Even if some people will steal your code, we (the authors) will always know how to make it better. Get my point? =)