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 with Words;   use Words;
  21 with FZ_Type; use FZ_Type;
  22 
  23 
  24 -- Fundamental Arithmetic operators on FZ:
  25 package FZ_Arith is
  26    
  27    pragma Pure;
  28    
  29    -- Destructive Add: X := X + Y; Overflow := Carry; optional OF_In
  30    procedure FZ_Add_D(X          : in out FZ;
  31                       Y          : in     FZ;
  32                       Overflow   : out    WBool;
  33                       OF_In      : in     WBool := 0);
  34    pragma Inline_Always(FZ_Add_D);
  35    
  36    -- Destructive Add: X := X + W; Overflow := Carry
  37    procedure FZ_Add_D_W(X        : in out FZ;
  38                         W        : in     Word;
  39                         Overflow : out    WBool);
  40    pragma Inline_Always(FZ_Add_D_W);
  41    
  42    -- Sum := X + Y; Overflow := Carry
  43    procedure FZ_Add(X          : in    FZ;
  44                     Y          : in    FZ;
  45                     Sum        : out   FZ;
  46                     Overflow   : out   WBool);
  47    pragma Inline_Always(FZ_Add);
  48    
  49    -- Gate = 1: Sum := X + Y; Overflow := Carry
  50    -- Gate = 0: Sum := X;     Overflow := 0
  51    procedure FZ_Add_Gated_O(X          : in  FZ;
  52                             Y          : in  FZ;
  53                             Gate       : in  WBool;
  54                             Sum        : out FZ;
  55                             Overflow   : out WBool);
  56    pragma Inline_Always(FZ_Add_Gated_O);
  57    
  58    -- Same as FZ_Add_Gated_O, but without Overflow output
  59    procedure FZ_Add_Gated(X          : in  FZ;
  60                           Y          : in  FZ;
  61                           Gate       : in  WBool;
  62                           Sum        : out FZ);
  63    pragma Inline_Always(FZ_Add_Gated);
  64    
  65    -- Destructive Subtract: X := X - Y; Underflow := Borrow
  66    procedure FZ_Sub_D(X          : in out FZ;
  67                       Y          : in     FZ;
  68                       Underflow  : out    WBool);
  69    pragma Inline_Always(FZ_Sub_D);
  70    
  71    -- Difference := X - W; Underflow := Borrow
  72    procedure FZ_Sub_W(X          : in  FZ;
  73                       W          : in  Word;
  74                       Difference : out FZ;
  75                       Underflow  : out WBool);
  76    pragma Inline_Always(FZ_Sub_W);
  77    
  78    -- Difference := X - Y; Underflow := Borrow
  79    procedure FZ_Sub(X          : in  FZ;
  80                     Y          : in  FZ;
  81                     Difference : out FZ;
  82                     Underflow  : out WBool);
  83    pragma Inline_Always(FZ_Sub);
  84    
  85    -- Destructive: If Cond is 1, NotN := ~N; otherwise NotN := N.
  86    procedure FZ_Not_Cond_D(N    : in out FZ;
  87                            Cond : in     WBool);
  88    pragma Inline_Always(FZ_Not_Cond_D);
  89    
  90    -- Subtractor that gets absolute value if underflowed, in const. time
  91    procedure FZ_Sub_Abs(X          : in FZ;
  92                         Y          : in FZ;
  93                         Difference : out FZ;
  94                         Underflow  : out WBool);
  95    pragma Inline_Always(FZ_Sub_Abs);
  96    
  97 end FZ_Arith;