File : w_mul.ads

   1 ------------------------------------------------------------------------------
   2 ------------------------------------------------------------------------------
   3 -- This file is part of 'Finite Field Arithmetic', aka 'FFA'.               --
   4 --                                                                          --
   5 -- (C) 2018 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 with Words; use Words;
  21 
  22 
  23 package W_Mul is
  24    
  25    pragma Pure;
  26    
  27    -- The bitness of a Half-Word
  28    HalfBitness : constant Positive := Bitness / 2;
  29    subtype HalfWord is Word range 0 .. 2**HalfBitness;
  30    
  31    -- The number of bytes in a Half-Word
  32    HalfByteness : constant Positive := Byteness / 2;
  33    
  34    -- Multiply half-words X and Y, producing a Word-sized product (Iron)
  35    function Mul_HalfWord_Iron(X : in HalfWord; Y : in HalfWord) return Word;
  36    pragma Inline_Always(Mul_HalfWord_Iron);
  37    
  38    -- Multiply half-words X and Y, producing a Word-sized product (Egyptian)
  39    function Mul_HalfWord_Soft(X : in HalfWord; Y : in HalfWord) return Word;
  40    pragma Inline_Always(Mul_HalfWord_Soft);
  41    
  42    -- Get the bottom half of a Word
  43    function BottomHW(W : in Word) return HalfWord;
  44    pragma Inline_Always(BottomHW);
  45    
  46    -- Get the top half of a Word
  47    function TopHW(W : in Word) return HalfWord;
  48    pragma Inline_Always(TopHW);
  49    
  50    -- Carry out X*Y mult, return lower word XY_LW and upper word XY_HW (Iron)
  51    procedure Mul_Word(X     : in Word;  Y     : in Word;
  52                       XY_LW : out Word; XY_HW : out Word);
  53    pragma Inline_Always(Mul_Word);
  54    
  55 end W_Mul;