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From: berndtrog@yahoo.com (Bernd Trog)
Newsgroups: comp.lang.ada,comp.arch.embedded
Subject: Type-safe low-level programming?
Date: 17 Feb 2003 16:06:56 -0800
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Date: 2003-02-18T00:06:56+00:00
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Hi,
lets say I've something like this:

pragma No_Run_Time;

type Bit_Number is range 0 .. 7;
type Address_Type is range 0 .. 16#ff#;

Register_A : constant Address_Type := 1;
Bit_A1 : constant Bit_Number := 4;  --Register A, Bit 4
Bit_A2 : constant Bit_Number := 1;
Bit_A3 : constant Bit_Number := 7;

Register_B : constant Address_Type = 2;
Bit_B1 : constant Bit_Number :=4;
Bit_B2 : constant Bit_Number :=2;
Bit_B3 : constant Bit_Number :=5;
[...]
Register_Z : constant Address_Type = 2;
Bit_Z1 : constant Bit_Number :=6;
Bit_Z2 : constant Bit_Number :=0;
Bit_Z3 : constant Bit_Number :=5;

procedure Set_Bit( Adr : in Address_Type; Nr : in Bit_Number );
procedure Clear_Bit( Adr : in Address_Type; Nr : in Bit_Number );

On a not-so-good day I wrote:
Set_Bit( Register_A, Bit_B3 );
and found my error days later :-(

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


Bernd