Re: Help with type conversion needed

[njb@res.eng.uiowa.edu (Nate Bohlmann)]

First of all, let me thank everyone who has been trying to help with this
problem.  This is an area of Ada I am not well versed in at all and I 
appreciate the willingness to wade through a poorly specified problem.

Robert Dewar (dewar@cs.nyu.edu) wrote:
: Geert suggests

:    function To_Unsigned_16_B(S : Signed_16) return Unsigned_16 is
:       type Modular_16 is mod 2**16;
:       function To_Modular is
:          new Unchecked_Conversion(Signed_16, Modular_16);
:       function To_Unsigned is
:          new Unchecked_Conversion(Modular_16, Unsigned_16);
:    begin
:       return To_Unsigned(To_Modular(S) xor 16#8000#);
:    end To_Unsigned_16_B;

: I find the use of xor obscure here, and it illustrates a danger of making
: such logical operations available, they tend to get overused.

: In the logical statement of the problem, the issue is to add 32768 to the
: result, so it is much clearer to write:

:       return To_Unsigned (To_Modular(S) + 32_768);


After twiddling with the bits, I now understand why this works.. :-) Thanks
again to everyone who helped out on this..

Nate

--
Nathan Bohlmann                           preferred->   njb@res.eng.uiowa.edu
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University of Iowa, Iowa City, IA                           njb@eng.uiowa.edu
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