Re: Reading Float Data from a binary file into ada

[Martin Dowie <martin.dowie@btopenworld.com.delete>]

frikk wrote:
[snip]
> Niklas - I think this is exactly what I need to do.
> 
> Martin - Thank you for the example. I will go through that and see 
> what I can use - it looks very useful though.  May I get some 
> clarification on exactly what this line does:
>     type FP is delta FP_Delta range -2.0**15 .. 2.0**15-FP_Delta;
>     for FP'Small use FP_Delta;
>     for FP'Size  use 32;
> 
> What is the delta used for?

The delta means the type is a 'fixed point' type (a real but not a 
'float'). It's an abstraction of an integer with a fractional LSB.

See http://www.adapower.com/rm95.php for a technical specification, or 
see 
http://www.adapower.com/launch.php?URL=http%3A%2F%2Fwww.it.bton.ac.uk%2Fstaff%2Fje%2Fadacraft%2F 
for an introduction to then.

With the 'delta' you specify the minimum "LSB" your willing to accept in 
terms of accuracy - the compiler is free to give you better! In practice 
the 'delta' is best defined as a power-of-2 (and a compiler isn't likely 
to change that!).

If you need an "LSB" that's a power-of-10, use a 'decimal type'. All 
covered in John's book.
Cheers
-- Martin