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ffa_ch1_genesis.kv      1 ------------------------------------------------------------------------------
ffa_ch1_genesis.kv      2 ------------------------------------------------------------------------------
ffa_ch1_genesis.kv      3 -- This file is part of 'Finite Field Arithmetic', aka 'FFA'.               --
ffa_ch1_genesis.kv      4 --                                                                          --
ffa_ch1_genesis.kv      5 -- (C) 2017 Stanislav Datskovskiy ( www.loper-os.org )                      --
ffa_ch1_genesis.kv      6 -- http://wot.deedbot.org/17215D118B7239507FAFED98B98228A001ABFFC7.html     --
ffa_ch1_genesis.kv      7 --                                                                          --
ffa_ch1_genesis.kv      8 -- You do not have, nor can you ever acquire the right to use, copy or      --
ffa_ch1_genesis.kv      9 -- distribute this software ; Should you use this software for any purpose, --
ffa_ch1_genesis.kv     10 -- or copy and distribute it to anyone or in any manner, you are breaking   --
ffa_ch1_genesis.kv     11 -- the laws of whatever soi-disant jurisdiction, and you promise to         --
ffa_ch1_genesis.kv     12 -- continue doing so for the indefinite future. In any case, please         --
ffa_ch1_genesis.kv     13 -- always : read and understand any software ; verify any PGP signatures    --
ffa_ch1_genesis.kv     14 -- that you use - for any purpose.                                          --
ffa_ch1_genesis.kv     15 --                                                                          --
ffa_ch1_genesis.kv     16 -- See also http://trilema.com/2015/a-new-software-licensing-paradigm .     --
ffa_ch1_genesis.kv     17 ------------------------------------------------------------------------------
ffa_ch1_genesis.kv     18 ------------------------------------------------------------------------------
ffa_ch1_genesis.kv     19 
ffa_ch1_genesis.kv     20 with Word_Ops; use Word_Ops;
ffa_ch1_genesis.kv     21 
ffa_ch1_genesis.kv     22 -- Fundamental Arithmetic operators on FZ:
ffa_ch1_genesis.kv     23 package body FZ_Arith is
ffa_ch1_genesis.kv     24    
ffa_ch1_genesis.kv     25    -- Sum := X + Y; Overflow := Carry
ffa_ch1_genesis.kv     26    procedure FZ_Add(X          : in  FZ;
ffa_ch1_genesis.kv     27                     Y          : in  FZ;
ffa_ch1_genesis.kv     28                     Sum        : out FZ;
ffa_ch1_genesis.kv     29                     Overflow   : out WBool) is
ffa_ch1_genesis.kv     30       Carry : WBool := 0;
ffa_ch1_genesis.kv     31    begin
ffa_ch1_genesis.kv     32       for i in X'Range loop
ffa_ch1_genesis.kv     33          declare
ffa_ch1_genesis.kv     34             A : constant Word := X(I);
ffa_ch1_genesis.kv     35             B : constant Word := Y(I);
ffa_ch1_genesis.kv     36             S : constant Word := A + B + Carry;
ffa_ch1_genesis.kv     37          begin
ffa_ch1_genesis.kv     38             Sum(i) := S;
ffa_ch1_genesis.kv     39             Carry  := W_Carry(A, B, S);
ffa_ch1_genesis.kv     40          end;
ffa_ch1_genesis.kv     41       end loop;
ffa_ch1_genesis.kv     42       Overflow := Carry;
ffa_ch1_genesis.kv     43    end FZ_Add;
ffa_ch1_genesis.kv     44    pragma Inline_Always(FZ_Add);
ffa_ch1_genesis.kv     45    
ffa_ch1_genesis.kv     46    
ffa_ch1_genesis.kv     47    -- Difference := X - Y; Underflow := Borrow
ffa_ch1_genesis.kv     48    procedure FZ_Sub(X          : in  FZ;
ffa_ch1_genesis.kv     49                     Y          : in  FZ;
ffa_ch1_genesis.kv     50                     Difference : out FZ;
ffa_ch1_genesis.kv     51                     Underflow  : out WBool) is
ffa_ch1_genesis.kv     52       Borrow : WBool := 0;
ffa_ch1_genesis.kv     53    begin
ffa_ch1_genesis.kv     54       for i in 0 .. Word_Index(X'Length - 1) loop
ffa_ch1_genesis.kv     55          declare
ffa_ch1_genesis.kv     56             A : constant Word := X(X'First + i);
ffa_ch1_genesis.kv     57             B : constant Word := Y(Y'First + i);
ffa_ch1_genesis.kv     58             S : constant Word := A - B - Borrow;
ffa_ch1_genesis.kv     59          begin
ffa_ch1_genesis.kv     60             Difference(Difference'First + i) := S;
ffa_ch1_genesis.kv     61             Borrow := W_Borrow(A, B, S);
ffa_ch1_genesis.kv     62          end;
ffa_ch1_genesis.kv     63       end loop;
ffa_ch1_genesis.kv     64       Underflow := Borrow;
ffa_ch1_genesis.kv     65    end FZ_Sub;
ffa_ch1_genesis.kv     66    pragma Inline_Always(FZ_Sub);
ffa_ch1_genesis.kv     67    
ffa_ch1_genesis.kv     68 end FZ_Arith;