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Leif: On Thu, 27 September 2001, "Leif Svalgaard" wrote: > Well, the RISC code to check if a pointer is valid is: > LQ R6, addr ; load pointer into R6, R7. set bit in exception reg if no tag > TXER nn ; trap if no tag > > to me that is software. The trap can be disabled by replacing the TXER > instruction by a NOOP. > > The overhead is the TXER instruction and is not unacceptable. I would expect a software function that tells me whether a pointer is valid. The alternative might be having to use the pointer to see if an exception is raised and then having to properly handle that exception. I'd find a software test very convenient. However, I'm not sure I see that this is really anything more than,... uh... well, a convenient way for a program to tell whether a pointer is valid. Tom Liotta (p.s. to anyone who's curious: Yes, I bought the book but haven't learned at all yet.) -- Tom Liotta The PowerTech Group, Inc. 19426 68th Avenue South Kent, WA 98032 Phone 253-872-7788 Fax 253-872-7904 http://www.400Security.com ___________________________________________________ The ALL NEW CS2000 from CompuServe Better! Faster! More Powerful! 250 FREE hours! Sign-on Now! http://www.compuserve.com/trycsrv/cs2000/webmail/
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