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=1.3 required=5.0 tests=BAYES_00,INVALID_MSGID, MSGID_RANDY autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,f495c7652c09dd8c X-Google-Attributes: gid103376,public From: Robert Dewar Subject: Re: Does this model work ? Date: 1999/05/17 Message-ID: <7hpdc9$jdt$1@nnrp1.deja.com>#1/1 X-Deja-AN: 478762576 References: <373e38e2.31311363@news2.ibm.net> <7hhj6q$cjn$1@nnrp1.deja.com> <7hmda1$khp$1@nnrp1.deja.com> <7hpbco$hsi$1@nnrp1.deja.com> X-Http-Proxy: 1.0 x22.deja.com:80 (Squid/1.1.22) for client 205.232.38.14 Organization: Deja.com - Share what you know. Learn what you don't. X-Article-Creation-Date: Mon May 17 15:42:01 1999 GMT Newsgroups: comp.lang.ada X-Http-User-Agent: Mozilla/4.04 [en] (OS/2; I) Date: 1999-05-17T00:00:00+00:00 List-Id: In article <7hpbco$hsi$1@nnrp1.deja.com>, jrcarter001@my-dejanews.com wrote: > In article <7hmda1$khp$1@nnrp1.deja.com>, > The code has timing requirements, and the Ada-83 compiler had > problems with low-level bit manipulation. Converting to > Boolean arrays was too slow This seems not a language issue at all. If for some reason your boolean data is in the form of integers, instead of packed bit arrays to start with, converting to packed bit arrays should require an unchecked conversion that takes zero time. Yes, you may have to parametrize endianess here, and so the one thing that was missing in Ada 83 was a standardized way to do this, but that is hardly fundamental. It just means you have one boolean constant that needs specialization. > More significantly, the Ada tasking implementation did not > allow them to use tasks and meet their timing requirements, > leading to OS calls Again, I would hesitate to say this is a language issue. A number of Ada 83 compilers provided passive tasks with actually slightly better performance than protected types (which have a bit too much baggage for really efficient implementation, unless you adopt the RP profile). It is most certainly the case that Ada 95 has improved the portability in some cases, and indeed these two features were provided with this in mind. What I am really pointing out is that it was not at all necessary, even in Ada 83, to give up on portability so quickly. It would just have taken a bit more care in compiler selection and coding style. Note that if performance is an issue, then you have to be careful about compiler selection anyway. There is nothing at all in the Ada 95 standard that says that protected types or modular logical operations have to be implemented efficiently. --== Sent via Deja.com http://www.deja.com/ ==-- ---Share what you know. Learn what you don't.---