<html><head><base href="x-msg://75/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">But TInt will do what you want. You just need to check bounds. TInt does mean "target INTEGER": is the way one does arithmetic on a host that doesn't support the range of the target. You cannot do constant folding safely without checking for overflow otherwise you violate the intent of the language (i.e., that some targets might check for overflow...)<div><br><div>
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"><div><font class="Apple-style-span" color="#0000FF"><font class="Apple-style-span" face="Gill Sans"><span class="Apple-style-span" style="color: rgb(0, 0, 255); font-family: 'Gill Sans'; "><span class="Apple-style-span" style="color: rgb(0, 0, 255); font-family: 'Gill Sans'; ">Antony Hosking</span></span></font></font><font class="Apple-style-span" face="Gill Sans"><span class="Apple-style-span" style="font-family: 'Gill Sans'; "><span class="Apple-style-span" style="font-family: 'Gill Sans'; "><span class="Apple-converted-space"> </span>|<span class="Apple-converted-space"> </span></span></span><span class="Apple-style-span" style="font-family: 'Gill Sans'; "><span class="Apple-style-span" style="font-family: 'Gill Sans'; ">Associate Professor</span></span><span class="Apple-style-span" style="font-family: 'Gill Sans'; "><span class="Apple-style-span" style="font-family: 'Gill Sans'; "> | Computer Science | Purdue University</span></span></font></div><div><font class="Apple-style-span" face="GillSans-Light"><span class="Apple-style-span" style="font-family: GillSans-Light; 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<br><div><div>On 25 Feb 2010, at 18:18, Jay K wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div class="hmmessage" style="font-size: 10pt; font-family: Verdana; ">Ok, I think maybe I should go back to the version where the type carries precision and each function is a small wrapper over TInt where I extend, call TInt, and then checked truncate.<br>Or at least call TInt and checked truncate, maybe no need for extend.<br>Something like that.<br> <br> <br>That will still leave the hard work in TInt.<br> <br> <br>I had hoped TInt could do "everything" for me.<br>It is a little disappointing -- it was for doing "target math", which is what I want, but now it is just for doing 64bit math on any host. Probably should be called Int64..<br> <br> <br>On the other hand, m3back historically just did host INTEGER math, no overflow checks. So maybe ok asis.<br>Adding the overflow checks found overflow in user source though, so I think a good thing.<br>I'll probably just go back a day or so, as described, where each function in M3BackInt/M3BackWord is about one line. No need for th TInt/TWord changes then, even though they were acceptable.<br> <br> - Jay<br><br> <br><hr id="stopSpelling">From:<span class="Apple-converted-space"> </span><a href="mailto:hosking@cs.purdue.edu">hosking@cs.purdue.edu</a><br>Date: Thu, 25 Feb 2010 12:20:49 -0500<br>To:<span class="Apple-converted-space"> </span><a href="mailto:jay.krell@cornell.edu">jay.krell@cornell.edu</a><br>CC:<span class="Apple-converted-space"> </span><a href="mailto:m3devel@elegosoft.com">m3devel@elegosoft.com</a><br>Subject: Re: [M3devel] TInt/TWord/m3back<br><br>This all speaks to your trying to use TInt for purposes it was never intended. It is there in support of the compiler front-end not compiler back-ends.<div><div><div><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><div style="word-wrap: break-word; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><div><span class="ecxApple-style-span" style="font-size: medium; "><font class="ecxApple-style-span" color="#0000ff" face="'Gill Sans'"><br></font></span></div></span></span></span></span></span></span></span></span></div></span></span></div><div><div>On 25 Feb 2010, at 08:24, Jay K wrote:</div><br class="ecxApple-interchange-newline"><blockquote><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal medium/normal Helvetica; white-space: normal; letter-spacing: normal; word-spacing: 0px; "><div class="ecxhmmessage" style="font-family: Verdana; font-size: 10pt; ">Tony, it should now be much closer to your intent.<br> I grant maybe the constants are misplaced, and I should try again to use ToBytes.<br> <br> <br>I'm worried though.<br>It used to be I could do:<br> <br> <br>TInt.Add(Int{4,FF,FF,FF,7}, One)<br></div></span></blockquote><blockquote><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal medium/normal Helvetica; white-space: normal; letter-spacing: normal; word-spacing: 0px; "><div class="ecxhmmessage" style="font-family: Verdana; font-size: 10pt; ">and be told it overflowed, in 4 bytes of precision.<br></div></span></blockquote><div><br></div><div>You must check explicitly that there is no overflow. This is easy enough.</div><div><br></div><div>TInt.LT(result, Target.Int32.min) OR TInt.LT(Target.Int32.max, result)</div><br><blockquote><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal medium/normal Helvetica; white-space: normal; letter-spacing: normal; word-spacing: 0px; "><div class="ecxhmmessage" style="font-family: Verdana; font-size: 10pt; "> Now it'll just do it in 8 and no overflow.<br> <br> <br>And chop always succeeds.</div></span></blockquote><blockquote><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal medium/normal Helvetica; white-space: normal; letter-spacing: normal; word-spacing: 0px; "><div class="ecxhmmessage" style="font-family: Verdana; font-size: 10pt; "> <br>Maybe:<br> <br> <br>PROCEDURE CheckChop (VAR r: Int; n: CARDINAL) =<br> BEGIN<br> IF And (r [n-1], SignMask) = 0<br> THEN FOR i := n TO LAST(Int) DO IF r [i] # 0 THEN RETURN FALSE END; END;<br> ELSE FOR i := n TO LAST(Int) DO IF r [i] # Mask THEN RETURN FALSE END; END;<br> END;<br> RETURN TRUE;<br> END CheckChop;<br><br>?<br><br> - Jay<br></div></span></blockquote></div><br></div></div></div></span><br class="Apple-interchange-newline"></blockquote></div><br></div></body></html>