Path: csiph.com!eternal-september.org!feeder.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Keith Thompson Newsgroups: comp.lang.c Subject: Re: "Let's Stop Bashing C" Date: Thu, 08 Dec 2016 08:34:06 -0800 Organization: None to speak of Lines: 82 Message-ID: References: <8f359715-238c-42b4-b53f-5c5511725fdb@googlegroups.com> <87y3zsfnep.fsf@bsb.me.uk> <87fum0ezb6.fsf@bsb.me.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Info: mx02.eternal-september.org; posting-host="8f45946c30f4b59560518fab20622d5e"; logging-data="30454"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/S1ZqkBSge2n2+jEHJrbdN" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) Cancel-Lock: sha1:OpPXkHqXSB4S4NCcJyhmwD4mmuw= sha1:rFa0x0c0+nVhnza1bmBeya8lwUs= Xref: csiph.com comp.lang.c:98388 jacobnavia writes: > Le 08/12/2016 á 02:09, Keith Thompson a écrit : >> jacobnavia writes: >>> Le 08/12/2016 á 00:32, Keith Thompson a écrit : >>>> Sets what flag? My understanding (based mostly on reading this >>>> discussion) is that the Alpha doesn't have a hardware "overflow flag". >>> >>> No. Like many other processor it uses the opcodes to provoke an >>> exception, meaning that if you want overflow check with special >>> instructions, you have caught the overflow signal and have a routine >>> that could give some information like the line and file of the fault. >> >> Upthread, you said: "Any overflow trap sets that flag!" Was that >> statement incorrect? > > I think understanding that is beyond your abilities Thompson. Here we go again. > The only objective of your posts is to point out some imperfection in > what I write to ask with your habitual cynism: No, the objective of my post was to ask you a question, to clarify something you wrote earlier that I'm not sure I understood. What is beyond my understanding is why you insist on treating a simple question as an insult. > Did I understand incorrectly sir? Obviously. > Your were wrong there? What? >> In the past, you've talked about ways to give a C program access to an >> "overflow flag". Are you now talking more generally about ways to >> detect and handle overflow, without necessarily using an actual flag? > > With access to the overflow flag I was speaking about many processors > that have an actual flag. Yes, and I was asking about machines that don't have an actual flag. > RISC machines generate traps or whatever. That was never the point. The > point is to give access to the programmer to handling that situation. Fine, how do you propose to give that access on a system that doesn't have an actual flag? Given a compiler that provides the features you suggest, can I write code that will work correctly on, say, both x86 and alpha? >> Or do you propose to create a flag in software on systems that don't >> have it in hardware? > > I have mentioned the way it is done in lcc-win. If you've discussed it in detail, I don't recall. You've talked about setting a flag. How would that work on Alpha? >> If you're modifying what you said earlier, that's fine. I'm just trying >> to understand what you're saying. > > "I am just trying to understand"... since six and halmf years some > people here do not get it. No, I'm asking a specific question about something you wrote a few days ago. > I am wasting my time here. Stop being so damned paranoid. I am not your enemy. If you want to discuss this further, you can reply to the e-mail I sent you on November 18. I expect you'll continue to ignore it, but I'm prepared to be pleasantly surprised. -- Keith Thompson (The_Other_Keith) kst-u@mib.org Working, but not speaking, for JetHead Development, Inc. "We must do something. This is something. Therefore, we must do this." -- Antony Jay and Jonathan Lynn, "Yes Minister"