Re: copying data between memory locations

[anon@anon.org (anon)]

-------------------------------------------
pragma Ada_83 ; -- limit GNAT to Ada 83. --
-------------------------------------------
with Interfaces ;
with System ;

procedure ytest is

   function Read_Memory ( Addr : System.Address ) 
                return Interfaces.Unsigned_8 is

     begin -- Read_Memory
       declare
         Mem : Interfaces.Unsigned_8 ;
         for Mem'Address use Addr ;
       begin
        return Mem ;
       end ;
     end Read_Memory ;

   procedure Write_Memory ( Addr : System.Address ; 
                            Data : Interfaces.Unsigned_8 ) is
     begin -- Write_Memory
       declare
         Mem : Interfaces.Unsigned_8 ;
         for Mem'Address use Addr ;
       begin
        Mem := Data ;
       end ;
     end Write_Memory ;


begin -- ytest
  null ;
end ytest ;

--
-- I think you can modify the code to fit your needs for records
--

In <1188809968.217323.145640@r29g2000hsg.googlegroups.com>,  jef.mangelschots@gmail.com writes:
>In our current design, we have a package that maintains a list of
>descriptors of various buffers in the application. We don't want to
>know their datatypes or how to write data into them. We only want to
>maintain a physical address of them and use that address to directly
>write data into these buffers (this data comes out incoming packets
>over the network).
>
>In C, this is very straightforward and use the address as a pointer
>and simply copy the packet into the memory location.
>I can't figure out a way to do this in Ada (at least not Ada83).
>
>suppose the following:
>
>type BUFFER_DETAILS_RECORD is
>record
>    num_bytes : integer;
>    start_address : system.address;
>end record;
>type BUFFER_DETAILS_ARRAY_TYPE is array(1..2) of
>BUFFER_DETAILS_RECORD;
>BUFFER_DETAILS : constant BUFFER_DETAILS_ARRAY_TYPE :=
>BUFFER_DETAILS_ARRAY_TYPE'(1 => (num_bytes => 100, start_address =>
>16#123# ),  1 => (num_bytes => 200, start_address => 16#456# ));
>
>procedure insert_block(idx : in integer; num_bytes : in integer;
>offset : in integer; data : BYTE_ARRAY_TYPE) is
>begin
>   ??? how do I copy the content of data into the memory pointed to by
>BUFFER_DETAILS(idx).start_address + offset
>end;
>