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Date: Tue, 05 Sep 2006 00:18:52 +0200
From: Gautier <gautier@fakeaddress.nil>
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Subject: Re: Q: Portable Ada floating-point binary I/O ?
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Date: 2006-09-05T00:18:52+02:00
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>>  > However, the problem is - what does "portable" mean here? Range and
>>  > precision cannot be portable, unless types aren't communicated as well.
>>
>> In my case, it should not be a problem; I have a deterministic file
>> format with some items expected as GL.Double, others as GL.Float. I
>> just want to ensure that the same file will be correctly read by a PC,
>> a Mac or a Playstation.

Stephen Leake:

> Those are all IEEE hardware, so all you need is byte-endianness
> conversions. See SAL http://stephe-leake.org/ada/sal.html for that, in
> particular sal-endianness_gnat_x86.ads, sal-network_order.ads, and
> sal-math_float-network_order.ads.

Thanks for the idea - however, for the project in question, I could restrict 
up to now the compiler and machine dependency to the bindings (GL,GLU,GLUT), 
and even there with very small differences. So I opted for a solution with 
attributes (Dmitry) where I split the value into integers (mantissa in 1 or 2 
parts, exponent), then slice them with a given endianess into bytes and merge 
them back for reading.

You can see the result there: http://www.mysunrise.ch/users/gdm/g3d.htm

Gautier
______________________________________________________________
Ada programming -- http://www.mysunrise.ch/users/gdm/gsoft.htm

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