<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">This does not make sense:<div><br></div><div>Here is the compiler's definition of the builtin CARDINAL type:</div><div><br></div><div><div>MODULE Card;</div><div><br></div><div>IMPORT SubrangeType, Target, TInt, Tipe, Int;</div><div><br></div><div>PROCEDURE Initialize () =</div><div> BEGIN</div><div> T := SubrangeType.New (TInt.Zero, Target.Integer.max, Int.T, TRUE);</div><div> Tipe.Define ("CARDINAL", T, TRUE);</div><div> END Initialize;</div><div><br></div><div>BEGIN</div><div>END Card.</div><div><br></div><div><br></div><div>Notice that it is a subrange type [0..LAST(INTEGER)].</div></div><div><br><div>
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<br><div><div>On 16 Dec 2009, at 17:56, Rodney M. Bates wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div>Tony Hosking wrote:<br><blockquote type="cite">On 16 Dec 2009, at 15:48, Peter Eiserloh wrote:<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"> <br></blockquote><blockquote type="cite"><blockquote type="cite">Hi Gang,<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">0 - CARDINALs are an integral type defined by the language<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">spec to be from 0 (zero) to MAXINT (not MAXCARD). Recently,<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">a change was made to CM3 to extend the language it recognizes<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">beyond the original language spec (SPWM3), now CM3 understands<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">a LONGINT. <br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">Was there a corresponding LONGCARD defined?<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"> <br></blockquote></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">No. But you can write:<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">[0L..LAST(LONGINT)]<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">just as<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">CARDINAL=[0..LAST(INTEGER)]<br></blockquote><blockquote type="cite"> <br></blockquote>Actually, the line above was once true, long long ago, when dinosaurs<br>roamed unfettered. CARDINAL was changed to be "just like"<br>(but not equal to) [0..LAST(INTEGER)]. This would have been<br>maybe early 1990s. <br>It took me years to figure out what this actually meant, and more<br>years to figure out why, but I believe I now know. CARDINAL is not an<br>equal type to [0..LAST(INTEGER)], but otherwise has all the same<br>properties. This makes the two mutually assignable, which is close<br>enough to equal to not matter in most contexts. The exact consequences<br>follow from other language rules. <br>The motivation is this: [0..LAST(INTEGER)] on a 32-bit machine is not<br>equal to [0..LAST(INTEGER)] on a 64-bit machine (or any combination of<br>machines with different values of LAST(INTEGER)), because the numeric<br>value of LAST(INTEGER) is part of the expanded type. The one place this<br>matters is if you use pickles to transfer data between machines of different<br>word sizes. If the type is [0..LAST(INTEGER)], the type signature (a hash<br>of the complete, expanded type definition) is different on the two machines,<br>and values of or containing this type cannot be transferred. Exact type<br>signature matches are used in pickles to find corresponding types when<br>reading. <br>But pickles handle different sized INTEGER values fine, expanding/shortening<br>as needed. Being a leaf in a type definition, INTEGER is always the same<br>type on any machine. So CARDINAL was changed to be its own unique<br>type too, so it would be possible also to transfer CARDINAL values in pickles<br>between different word sizes. <br>So, we really should have a LONGCARD, parallel to CARDINAL.<br><br>Note that this also affects network objects, which use pickles to transfer<br>values of the objects.<br><br><br><blockquote type="cite"><br></blockquote><blockquote type="cite"> <br></blockquote><blockquote type="cite"><blockquote type="cite">Can is use all 64-bits, or is it restricted to 63, like<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">the CARDINAL is only 31-bits.<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"> <br></blockquote></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">63 bits, since its underlying base type is LONGINT.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"> <br></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">+--------------------------------------------------------+<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">| Peter P. Eiserloh |<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">+--------------------------------------------------------+<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"> <br></blockquote></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"> <br></blockquote></div></blockquote></div><br></div></body></html>