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From: tmoran@bix.com
Subject: Re: Newbie question : types , representation
Date: 1999/08/24
Message-ID: <4Oyw3.549$W5.69009@typhoon-sf.snfc21.pbi.net>#1/1
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References: <37C1AA76.14D14819@tu-cottbus.de>
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 24 Aug 1999 08:23:44 PDT)
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NNTP-Posting-Date: Tue, 24 Aug 1999 08:23:44 PDT
Newsgroups: comp.lang.ada
Date: 1999-08-24T00:00:00+00:00
List-Id: <comp.lang.ada>

>From an old base64 decoder, slightly modified from Ada 83 to Ada 95:

  type bytes is mod 256;
  for bytes'size use 8;
  package out_io is new sequential_io(bytes);

  subtype base64s is integer range 0 .. 63;
  a_byte:bytes:=0;
  next_byte:bytes:=0;
  type slots is mod 4;
  pack_di:slots:=0;

  procedure put(n:in base64s) is
  begin
    case pack_di is
      when 0 => a_byte:=bytes(n)*4;
      when 1 => out_io.write(f_output, a_byte+bytes(n/16));
                a_byte:=bytes((n mod 16)*16);
      when 2 => out_io.write(f_output, a_byte+bytes(n/4));
                a_byte:=bytes(n mod 4)*64;
      when 3 => out_io.write(f_output, a_byte+bytes(n));
    end case;
    pack_di:=pack_di+1;
  end put;