Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.programming > #4771

Re: gcc-4.x.x and endianess

Show key headers only | View raw

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> On Sun, 14 Sep 2014 22:05:57 +0100, Ben Bacarisse wrote:
>
>> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
>> 
>>> On Sun, 14 Sep 2014 15:31:31 -0400, Bill Cunningham wrote:
>>>
>>>> I just write in C. With some 
>>>> machines you have to re-write code because of the machine's endianess. That 
>>>> might only be with assembley and old assemblers I don't know.
>>>
>>> That depends on how the code is written. With C chances are high, because
>>> it does not offer any means to handle endianness nor to declare types in a
>>> machine-independent way. But I guess people like C mostly for its
>>> deficiencies.
>> 
>> What means do other languages offer to handle endianness?
>
> 1. Types declared in problem space terms, when it is machine-independent
> and, thus, endianness-agnostic.

You seemed to draw a distinction between machine-independent types and
handling endianness.  The former I understand, it was the latter I was
unclear about.

> Like:
>
>    type Salary is range 0..1_000_000; -- I don't care about endianness

Are there any languages where the basic types *do* care about
endianness?  What would that look like from the point of view of the
program?

> [ which also presumes that the language does not provide means to expose
> endianness through legal operations defined on the type. E.g. whatever you
> write with the type the result would not depend on the endianness. In C you
> have shifts and type casts which expose endinness.

That's a common misconception about shifts in C.  It is also a common
misconception that casts expose endianness.  Obviously C *can* reveal
the representation of its types (though pointers and unions for
example) but casts are defined as value conversions in C.

> In a safe language such
> things if exist then guarded against unintentional use. ]
>
> 2. Control over the type representation aspects (endianness is one of them)
> when it must really be machine-dependent. E.g. see here
>
> http://en.wikibooks.org/wiki/Ada_Programming/Attributes/%27Bit_Order

I'm not sure which part of that page you are referring to because t does
not seem to be directly related to handling endianness.  In the end it
says:

  "The 'Bit_Order attribute is not intended to convert data between a
  big-endian and a little-endian machine (it affects bit numbering, not
  byte order)."

Could you give an example of an endianness problem that is solved using
this attribute?

-- 
Ben.

Back to comp.programming | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

gcc-4.x.x and endianess "Bill Cunningham" <nospam@nspam.invalid> - 2014-09-13 21:41 -0400
  Re: gcc-4.x.x and endianess "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2014-09-14 09:14 +0200
    Re: gcc-4.x.x and endianess "Bill Cunningham" <nospam@nspam.invalid> - 2014-09-14 15:31 -0400
      Re: gcc-4.x.x and endianess "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2014-09-14 21:38 +0200
        Re: gcc-4.x.x and endianess Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-09-14 22:05 +0100
          Re: gcc-4.x.x and endianess "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2014-09-15 09:40 +0200
            Re: gcc-4.x.x and endianess Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-09-15 11:51 +0100
              Re: gcc-4.x.x and endianess "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-09-15 13:49 +0100
              Re: gcc-4.x.x and endianess "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2014-09-15 17:16 +0200
                Re: gcc-4.x.x and endianess Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-09-15 22:23 +0100
                Re: gcc-4.x.x and endianess "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2014-09-16 10:44 +0200
                Re: gcc-4.x.x and endianess Kaz Kylheku <kaz@kylheku.com> - 2014-09-16 00:18 +0000
          Re: gcc-4.x.x and endianess BGB <cr88192@hotmail.com> - 2014-09-15 06:18 -0500
        Re: gcc-4.x.x and endianess "Bill Cunningham" <nospam@nspam.invalid> - 2014-09-15 14:23 -0400
          Re: gcc-4.x.x and endianess "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2014-09-15 21:08 +0200
            Re: gcc-4.x.x and endianess "Bill Cunningham" <nospam@nspam.invalid> - 2014-09-15 19:32 -0400
          Re: gcc-4.x.x and endianess Richard Heathfield <invalid@see.sig.invalid> - 2014-09-15 21:07 +0100
            Re: gcc-4.x.x and endianess "Bill Cunningham" <nospam@nspam.invalid> - 2014-09-15 21:48 -0400
  Re: gcc-4.x.x and endianess Jongware <jongware@no-spam.plz> - 2014-09-15 10:57 +0200
  Re: gcc-4.x.x and endianess "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-09-15 14:06 +0100
    Re: gcc-4.x.x and endianess "Bill Cunningham" <nospam@nspam.invalid> - 2014-09-15 21:50 -0400
      Re: gcc-4.x.x and endianess "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-09-17 09:54 +0100
        Re: gcc-4.x.x and endianess "Bill Cunningham" <nospam@nspam.invalid> - 2014-09-17 22:29 -0400

csiph-web