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-- This file is part of 'Finite Field Arithmetic', aka 'FFA'.               --
--                                                                          --
-- (C) 2017 Stanislav Datskovskiy ( www.loper-os.org )                      --
-- http://wot.deedbot.org/17215D118B7239507FAFED98B98228A001ABFFC7.html     --
--                                                                          --
-- You do not have, nor can you ever acquire the right to use, copy or      --
-- distribute this software ; Should you use this software for any purpose, --
-- or copy and distribute it to anyone or in any manner, you are breaking   --
-- the laws of whatever soi-disant jurisdiction, and you promise to         --
-- continue doing so for the indefinite future. In any case, please         --
-- always : read and understand any software ; verify any PGP signatures    --
-- that you use - for any purpose.                                          --
--                                                                          --
-- See also http://trilema.com/2015/a-new-software-licensing-paradigm .     --
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with FZ_Type; use FZ_Type;


package FZ_Mul is
   
   pragma Pure;
   
   -- Karatsuba Threshhold - at or below this many words, we use Comba mult.
   Karatsuba_Thresh : constant Indices := 8;
   
   -- Multiply. (CAUTION: UNBUFFERED)
   procedure FZ_Multiply(X     : in  FZ;
                         Y     : in  FZ;
                         XY    : out FZ);
   pragma Precondition(X'Length = Y'Length and
                         XY'Length = (X'Length + Y'Length));
   
   -- Comba's multiplier. (CAUTION: UNBUFFERED)
   procedure FZ_Mul_Comba(X     : in  FZ;
                          Y     : in  FZ;
                          XY    : out FZ);
   pragma Precondition(X'Length = Y'Length and
                         XY'Length = (X'Length + Y'Length));
   
   -- Karatsuba's Multiplier. (CAUTION: UNBUFFERED)
   procedure Mul_Karatsuba(X  : in  FZ;
                           Y  : in  FZ;
                           XY : out FZ);
   pragma Precondition(X'Length = Y'Length and
                         XY'Length = (X'Length + Y'Length) and
                         X'Length mod 2 = 0);
   -- CAUTION: Inlining prohibited for Mul_Karatsuba !
   
   -- Multiplier. Preserves the inputs.
   procedure FZ_Mult(X     : in  FZ;
                     Y     : in  FZ;
                     XY_Lo : out FZ;
                     XY_Hi : out FZ);
   pragma Precondition(X'Length = Y'Length and
                         XY_Lo'Length = XY_Hi'Length and
                         XY_Lo'Length = ((X'Length + Y'Length) / 2));
   
end FZ_Mul;