raw
ffa_ch4_ffacalc.kv      1 ------------------------------------------------------------------------------
ffa_ch4_ffacalc.kv      2 ------------------------------------------------------------------------------
ffa_ch4_ffacalc.kv      3 -- This file is part of 'Finite Field Arithmetic', aka 'FFA'.               --
ffa_ch4_ffacalc.kv      4 --                                                                          --
ffa_ch4_ffacalc.kv      5 -- (C) 2017 Stanislav Datskovskiy ( www.loper-os.org )                      --
ffa_ch4_ffacalc.kv      6 -- http://wot.deedbot.org/17215D118B7239507FAFED98B98228A001ABFFC7.html     --
ffa_ch4_ffacalc.kv      7 --                                                                          --
ffa_ch4_ffacalc.kv      8 -- You do not have, nor can you ever acquire the right to use, copy or      --
ffa_ch4_ffacalc.kv      9 -- distribute this software ; Should you use this software for any purpose, --
ffa_ch4_ffacalc.kv     10 -- or copy and distribute it to anyone or in any manner, you are breaking   --
ffa_ch4_ffacalc.kv     11 -- the laws of whatever soi-disant jurisdiction, and you promise to         --
ffa_ch4_ffacalc.kv     12 -- continue doing so for the indefinite future. In any case, please         --
ffa_ch4_ffacalc.kv     13 -- always : read and understand any software ; verify any PGP signatures    --
ffa_ch4_ffacalc.kv     14 -- that you use - for any purpose.                                          --
ffa_ch4_ffacalc.kv     15 --                                                                          --
ffa_ch4_ffacalc.kv     16 -- See also http://trilema.com/2015/a-new-software-licensing-paradigm .     --
ffa_ch4_ffacalc.kv     17 ------------------------------------------------------------------------------
ffa_ch4_ffacalc.kv     18 ------------------------------------------------------------------------------
ffa_ch4_ffacalc.kv     19 
ffa_ch4_ffacalc.kv     20 package body FZ_Lim is
ffa_ch4_ffacalc.kv     21    
ffa_ch4_ffacalc.kv     22    -- Determine if a proposed FFA Bitness is valid.
ffa_ch4_ffacalc.kv     23    function FZ_Valid_Bitness_P(B : in Positive) return Boolean is
ffa_ch4_ffacalc.kv     24       Result   : Boolean := False;
ffa_ch4_ffacalc.kv     25       T        : Natural := B;
ffa_ch4_ffacalc.kv     26       PopCount : Natural := 0;
ffa_ch4_ffacalc.kv     27    begin
ffa_ch4_ffacalc.kv     28       -- Supposing we meet the minimal bitness:
ffa_ch4_ffacalc.kv     29       if B >= FZ_Minimal_Bitness then
ffa_ch4_ffacalc.kv     30          while T > 0 loop
ffa_ch4_ffacalc.kv     31             if T mod 2 = 1 then
ffa_ch4_ffacalc.kv     32                PopCount := PopCount + 1;
ffa_ch4_ffacalc.kv     33             end if;
ffa_ch4_ffacalc.kv     34             T := T / 2;
ffa_ch4_ffacalc.kv     35          end loop;
ffa_ch4_ffacalc.kv     36          
ffa_ch4_ffacalc.kv     37          -- Is B a power of 2?
ffa_ch4_ffacalc.kv     38          if PopCount = 1 then
ffa_ch4_ffacalc.kv     39             Result := True;
ffa_ch4_ffacalc.kv     40          end if;
ffa_ch4_ffacalc.kv     41       end if;
ffa_ch4_ffacalc.kv     42       
ffa_ch4_ffacalc.kv     43       return Result;
ffa_ch4_ffacalc.kv     44    end FZ_Valid_Bitness_P;
ffa_ch4_ffacalc.kv     45    
ffa_ch4_ffacalc.kv     46 end FZ_Lim;