1 ------------------------------------------------------------------------------ 2 ------------------------------------------------------------------------------ 3 -- This file is part of 'Finite Field Arithmetic', aka 'FFA'. -- 4 -- -- 5 -- (C) 2019 Stanislav Datskovskiy ( www.loper-os.org ) -- 6 -- http://wot.deedbot.org/17215D118B7239507FAFED98B98228A001ABFFC7.html -- 7 -- -- 8 -- You do not have, nor can you ever acquire the right to use, copy or -- 9 -- distribute this software ; Should you use this software for any purpose, -- 10 -- or copy and distribute it to anyone or in any manner, you are breaking -- 11 -- the laws of whatever soi-disant jurisdiction, and you promise to -- 12 -- continue doing so for the indefinite future. In any case, please -- 13 -- always : read and understand any software ; verify any PGP signatures -- 14 -- that you use - for any purpose. -- 15 -- -- 16 -- See also http://trilema.com/2015/a-new-software-licensing-paradigm . -- 17 ------------------------------------------------------------------------------ 18 ------------------------------------------------------------------------------ 19 20 package body FZ_Lim is 21 22 -- Determine if a proposed FFA Bitness is valid. 23 function FZ_Valid_Bitness_P(B : in Positive) return Boolean is 24 Result : Boolean := False; 25 T : Natural := B; 26 PopCount : Natural := 0; 27 begin 28 -- Supposing we meet the minimal bitness: 29 if B >= FZ_Minimal_Bitness then 30 while T > 0 loop 31 PopCount := PopCount + T mod 2; 32 T := T / 2; 33 end loop; 34 35 -- Is B a power of 2? 36 if PopCount = 1 then 37 Result := True; 38 end if; 39 end if; 40 41 return Result; 42 end FZ_Valid_Bitness_P; 43 44 end FZ_Lim;