⟦3ebf98c21⟧

E3 Source Code



with Arithmetic;
use Arithmetic;
with Vstring_Type;
use Vstring_Type;

------------------------------------------------------------------------------
-- Copyright 1988 - 1991 by Rational, Santa Clara, California.
--
--                  All Rights Reserved.
--
-- Permission to use, copy, modify, and distribute this software and its
-- documentation for any purpose and without fee is hereby granted,
-- provided that the above copyright notice(s) appear in all copies and that
-- both that copyright notice(s) and this permission notice appear in
-- supporting documentation, and that the name of Rational not be used in
-- advertising or publicity pertaining to distribution of the software
-- without specific, written prior permission.
--
-- Rational disclaims all warranties with regard to this software, including
-- all implied warranties of merchantability and fitness, in no event shall
-- Rational be liable for any special, indirect or consequential damages or
-- any damages whatsoever resulting from loss of use, data or profits, whether
-- in an action of contract, negligence or other tortious action, arising out
-- of or in connection with the use or performance of this software.
------------------------------------------------------------------------------

function Vstring_Hash (Vstr : Vstring_Data) return S_Natural is
------------------------------------------------------------------------------
--  Vstr        - Specifies the string to hash
--
-- Computes a numeric value based upon the contents of the Vstring.
------------------------------------------------------------------------------
    Hash : S_Natural := 0;
    Tmp  : S_Natural := 0;
    Pos  : S_Natural := 1;
begin

----Loop over the entire contents.  Take each character and add it into the
--  hash.  Take care not to overflow.

    while Pos < Vstr.Length loop
        if Tmp > (S_Natural'Last - Character'Pos (Character'Last)) / 3 then
            if S_Natural'Last - Hash < Tmp then
                Hash := Hash / 2 + Tmp;
            else
                Hash := Hash + Tmp;
            end if;
            Tmp := 0;
        end if;
        Tmp := Tmp * 3 + Character'Pos (Vstr.Chars (Pos));
        Pos := Pos + 1;
    end loop;

---Add in any remaining hash bits and return.

    if S_Natural'Last - Hash < Tmp then
        Hash := Hash / 2 + Tmp;
    else
        Hash := Hash + Tmp;
    end if;
    return Hash;

end Vstring_Hash;
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⟦3ebf98c21⟧ Ada Source

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E3 Source Code

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