From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=BAYES_00,INVALID_DATE autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,2d886a1f8c2fd7b X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 1993-03-23 13:10:53 PST Newsgroups: comp.lang.ada Path: sparky!uunet!caen!sdd.hp.com!zaphod.mps.ohio-state.edu!uwm.edu!cs.utexas.edu!csc.ti.com!tilde.csc.ti.com!mksol!strohm From: strohm@mksol.dseg.ti.com (john r strohm) Subject: Re: How does Alsys index bit-arrays on Intel ? Message-ID: <1993Mar23.202742.26997@mksol.dseg.ti.com> Organization: Texas Instruments, Inc References: <1993Mar22.191652.16458@mksol.dseg.ti.com> <1993Mar23.023912.1083@rational.com> Distribution: inet Date: Tue, 23 Mar 1993 20:27:42 GMT Date: 1993-03-23T20:27:42+00:00 List-Id: In article ncohen@watson.ibm.com describes an Ada algorithm to determine which bit (most or least significant) is numbered how. The problem is that this tells only how that particular version of that particular compiler for that particular host and target numbers them. This does NOT give any assurance that a compiler from a competing vendor will do the same thing, nor does it even cover the case of another compiler from the same vendor, for the same host but a different target, or even (in a REALLY baroque scenario) for a subsequent release of the SAME compiler. The language of the standard allows the vendor to do what he/she wishes. This, in my personal opinion, is one of the few places where Ada goofs. Now, the flip side is that there is a good argument for making it implementation-dependent. Some machines still number bits left-to-right, while others number right-to-left, and we still have Endian problems every time we change processors (almost). Choosing one scheme and enforcing it is going to cause major heartburn for SOMEBODY, as they curse the standard because none of their databooks are useable: they all have the bits numbered backwards.