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From: jef.mangelschots@gmail.com
Newsgroups: comp.lang.ada
Subject: copying data between memory locations
Date: Mon, 03 Sep 2007 08:59:28 -0000
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Date: 2007-09-03T08:59:28+00:00
List-Id: <comp.lang.ada>

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;