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From: Hans-Bernhard Broeker <broeker@physik.rwth-aachen.de>
Newsgroups: comp.lang.ada,comp.arch.embedded
Subject: Re: Type-safe low-level programming?
Date: 18 Feb 2003 16:52:55 GMT
Organization: Aachen University of Technology (RWTH)
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In comp.arch.embedded Hans-Bernhard Broeker <broeker@physik.rwth-aachen.de> wrote:
> In comp.arch.embedded Bernd Trog <berndtrog@yahoo.com> wrote:

>> Now I wonder, if its possible to make 'Set_Bit' type-safe *without*
>> increasing the program memory size for every new register?

> The only way I see is to drop the idea of passing the register and the
> bit number inside that register as independent parameters 
[...]
>   Bit_A2 : constant Bit_Number := Register_A*8 + 1;

On second thinking, a better alternative is still possible.  But I'll
have to switch to C to explain it, because I don't speak Ada, so those
of you allergic to C may want shade their eyes....

typedef unsigned short   tByteNumber;
typedef unsinged char	 tBitNumber;

typedef struct {
	tByteNumber	byte_number;
	tBitNumber 	bit_number;
} tBitDefinition;

const tByteNumber Register_A = 8;
const bit_definition WhatEverThisDoes = {Register_A, 1};

inline void 
SetBit(tBitDefinition bit)
{
	USUAL_SETBIT_MACRO(bit.byte_number, bit.bit_number);
}
-- 
Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.