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Groups > comp.lang.java.programmer > #32410
| From | Martin Gregorie <martin@address-in-sig.invalid> |
|---|---|
| Newsgroups | comp.lang.java.programmer |
| Subject | Re: is the java compiler written in c |
| Date | 2015-08-22 17:55 +0000 |
| Organization | A noiseless patient Spider |
| Message-ID | <mrad2k$468$1@dont-email.me> (permalink) |
| References | (2 earlier) <7b5d28de-2f30-4db7-aec7-03bd9ce81d00@googlegroups.com> <mr6j27$4et$1@dont-email.me> <mr8ni4$p8f$1@speranza.aioe.org> <mr9nqt$m9d$3@dont-email.me> <mr9oqe$mn$1@dont-email.me> |
On Sat, 22 Aug 2015 13:11:41 +0100, Eternal Hope wrote:
> On 22/08/2015 12:53, Martin Gregorie wrote:
>> On Fri, 21 Aug 2015 22:42:11 -0400, Arne Vajhøj wrote:
>>
>>> To write an OS you need to get real close to the hardware and allow a
>>> lot of funky stuff.
>>>
>> Hardware emulation too. I started to write a 6809 emulator in Java, but
>> moved the project to C when I discovered what a pain it was going to be
>> to emulate the registers (8 or 16 bit unsigned arithmetic but with the
>> option to treat the LHS bit as the sign) It was *much* easier to simply
>> declare the registers as 'unsigned short' or 'unsigned byte' than it
>> was to fight with Java's insistence on signed arithmetic.
>
>
> https://docs.oracle.com/javase/8/docs/api/java/lang/Integer.html
>
> unsigned ops agogo
Integer is a bit too long for what I need: all the 6809 registers are 8
or 16 bits. Byte and Short are the obvious Java classes to use but, then
again, Integer,Byte and Short all only do a subset of unsigned
arithmetic. Since none of them do unsigned addition or subtraction and
none of them have any facilities for treating the MSB as a sign or
reporting overflow - all of which are needed to emulate the registers, it
remains much easier to do it in C.
This is just an observation that Java is unsuitable for some
applications, not a criticism.
Yeah, I know I could use native code for this sort of stuff but, as much
of the reason for using Java was to make the emulator fully portable,
dropping bits of native C into the mix would probably have impacted that
aim.
Meanwhile C fits the bill very nicely.
--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
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is the java compiler written in c gdotone@gmail.com - 2015-08-19 12:41 -0700
Re: is the java compiler written in c Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-08-19 16:06 -0400
Re: is the java compiler written in c gdotone@gmail.com - 2015-08-19 16:12 -0700
Re: is the java compiler written in c Martin Gregorie <martin@address-in-sig.invalid> - 2015-08-20 11:08 +0000
Re: is the java compiler written in c Arne Vajhøj <arne@vajhoej.dk> - 2015-08-20 20:34 -0400
Re: is the java compiler written in c Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-08-20 07:44 -0400
Re: is the java compiler written in c e.d.programmer@gmail.com - 2015-08-20 06:36 -0700
Re: is the java compiler written in c gdotone@gmail.com - 2015-08-20 18:58 -0700
Re: is the java compiler written in c Arne Vajhøj <arne@vajhoej.dk> - 2015-08-20 22:13 -0400
Re: is the java compiler written in c g g <gdotone@gmail.com> - 2015-08-20 19:57 -0700
Re: is the java compiler written in c Arne Vajhøj <arne@vajhoej.dk> - 2015-08-21 21:25 -0400
Re: is the java compiler written in c Eternal Hope <laughingspam99@gmail.com> - 2015-08-21 08:15 +0100
Re: is the java compiler written in c e.d.programmer@gmail.com - 2015-08-21 06:56 -0700
Re: is the java compiler written in c Eternal Hope <laughingspam99@gmail.com> - 2015-08-21 15:32 +0100
Re: is the java compiler written in c BGB <cr88192@hotmail.com> - 2015-08-21 16:51 -0500
Re: is the java compiler written in c Martin Gregorie <martin@address-in-sig.invalid> - 2015-08-21 23:32 +0000
Re: is the java compiler written in c BGB <cr88192@hotmail.com> - 2015-08-21 23:35 -0500
Re: is the java compiler written in c Arne Vajhøj <arne@vajhoej.dk> - 2015-08-21 22:39 -0400
Re: is the java compiler written in c BGB <cr88192@hotmail.com> - 2015-08-21 22:42 -0500
Re: is the java compiler written in c Martin Gregorie <martin@address-in-sig.invalid> - 2015-08-22 11:41 +0000
Re: is the java compiler written in c BGB <cr88192@hotmail.com> - 2015-08-22 10:03 -0500
Re: is the java compiler written in c Arne Vajhøj <arne@vajhoej.dk> - 2015-08-30 22:03 -0400
Re: is the java compiler written in c BGB <cr88192@hotmail.com> - 2015-08-31 01:09 -0500
Re: is the java compiler written in c Arne Vajhøj <arne@vajhoej.dk> - 2015-09-03 20:46 -0400
Re: is the java compiler written in c BGB <cr88192@hotmail.com> - 2015-09-04 10:01 -0500
Re: is the java compiler written in c Martin Gregorie <martin@address-in-sig.invalid> - 2015-08-22 11:37 +0000
Re: is the java compiler written in c Eternal Hope <laughingspam99@gmail.com> - 2015-08-22 12:56 +0100
Re: is the java compiler written in c Martin Gregorie <martin@address-in-sig.invalid> - 2015-08-22 18:04 +0000
Re: is the java compiler written in c BGB <cr88192@hotmail.com> - 2015-08-22 14:27 -0500
Re: is the java compiler written in c Arne Vajhøj <arne@vajhoej.dk> - 2015-08-30 22:06 -0400
Re: is the java compiler written in c Eternal Hope <laughingspam99@gmail.com> - 2015-08-22 10:31 +0100
Re: is the java compiler written in c BGB <cr88192@hotmail.com> - 2015-08-23 01:31 -0500
Re: is the java compiler written in c Arne Vajhøj <arne@vajhoej.dk> - 2015-08-21 22:42 -0400
Re: is the java compiler written in c Martin Gregorie <martin@address-in-sig.invalid> - 2015-08-22 11:53 +0000
Re: is the java compiler written in c Eternal Hope <laughingspam99@gmail.com> - 2015-08-22 13:11 +0100
Re: is the java compiler written in c Martin Gregorie <martin@address-in-sig.invalid> - 2015-08-22 17:55 +0000
Re: is the java compiler written in c Eternal Hope <laughingspam99@gmail.com> - 2015-08-22 19:59 +0100
Re: is the java compiler written in c Gene Wirchenko <genew@telus.net> - 2015-08-26 09:44 -0700
Re: is the java compiler written in c Arne Vajhøj <arne@vajhoej.dk> - 2015-08-30 22:11 -0400
Re: is the java compiler written in c Arne Vajhøj <arne@vajhoej.dk> - 2015-08-19 19:35 -0400
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