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ffa_ch3_shifts.kv       1 ------------------------------------------------------------------------------
ffa_ch3_shifts.kv       2 ------------------------------------------------------------------------------
ffa_ch3_shifts.kv       3 -- This file is part of 'Finite Field Arithmetic', aka 'FFA'.               --
ffa_ch3_shifts.kv       4 --                                                                          --
ffa_ch3_shifts.kv       5 -- (C) 2017 Stanislav Datskovskiy ( www.loper-os.org )                      --
ffa_ch3_shifts.kv       6 -- http://wot.deedbot.org/17215D118B7239507FAFED98B98228A001ABFFC7.html     --
ffa_ch3_shifts.kv       7 --                                                                          --
ffa_ch3_shifts.kv       8 -- You do not have, nor can you ever acquire the right to use, copy or      --
ffa_ch3_shifts.kv       9 -- distribute this software ; Should you use this software for any purpose, --
ffa_ch3_shifts.kv      10 -- or copy and distribute it to anyone or in any manner, you are breaking   --
ffa_ch3_shifts.kv      11 -- the laws of whatever soi-disant jurisdiction, and you promise to         --
ffa_ch3_shifts.kv      12 -- continue doing so for the indefinite future. In any case, please         --
ffa_ch3_shifts.kv      13 -- always : read and understand any software ; verify any PGP signatures    --
ffa_ch3_shifts.kv      14 -- that you use - for any purpose.                                          --
ffa_ch3_shifts.kv      15 --                                                                          --
ffa_ch3_shifts.kv      16 -- See also http://trilema.com/2015/a-new-software-licensing-paradigm .     --
ffa_ch3_shifts.kv      17 ------------------------------------------------------------------------------
ffa_ch3_shifts.kv      18 ------------------------------------------------------------------------------
ffa_ch3_shifts.kv      19 
ffa_ch2_logicals.kv    20 with Word_Ops; use Word_Ops;
ffa_ch2_logicals.kv    21 
ffa_ch2_logicals.kv    22 
ffa_ch2_logicals.kv    23 package body FZ_Basic is
ffa_ch2_logicals.kv    24    
ffa_ch2_logicals.kv    25    ---------------------------------------------------------------------------
ffa_ch2_logicals.kv    26    -- Fundamental Operations on FZ (finite integers)
ffa_ch2_logicals.kv    27    ---------------------------------------------------------------------------
ffa_ch2_logicals.kv    28    
ffa_ch5_egypt.kv       29    -- Determine the Bitness of N
ffa_ch5_egypt.kv       30    function FZ_Bitness(N : in FZ) return Bit_Count is
ffa_ch5_egypt.kv       31    begin
ffa_ch5_egypt.kv       32       return N'Length * Words.Bitness;
ffa_ch5_egypt.kv       33    end FZ_Bitness;
ffa_ch5_egypt.kv       34    
ffa_ch5_egypt.kv       35    
ffa_ch13_measure_...   36    -- Determine the Bitness of the given FZ's Length
ffa_ch13_measure_...   37    function FZ_Bitness_Log2(N : in FZ) return Positive is
ffa_ch13_measure_...   38       W : Bit_Count := N'Length;
ffa_ch13_measure_...   39       R : Positive  := 1;
ffa_ch13_measure_...   40    begin
ffa_ch13_measure_...   41       while W > 1 loop
ffa_ch13_measure_...   42          W := W / 2;
ffa_ch13_measure_...   43          R := R + 1;
ffa_ch13_measure_...   44       end loop;
ffa_ch13_measure_...   45       return R - 1;
ffa_ch13_measure_...   46    end FZ_Bitness_Log2;
ffa_ch13_measure_...   47    
ffa_ch13_measure_...   48    
ffa_ch2_logicals.kv    49    -- N := 0
ffa_ch2_logicals.kv    50    procedure FZ_Clear(N : out FZ) is
ffa_ch2_logicals.kv    51    begin
ffa_ch2_logicals.kv    52       N := (others => 0);
ffa_ch2_logicals.kv    53    end FZ_Clear;
ffa_ch2_logicals.kv    54    
ffa_ch2_logicals.kv    55    
ffa_ch4_ffacalc.kv     56    -- Set given FZ to a given truth value
ffa_ch4_ffacalc.kv     57    procedure WBool_To_FZ(V : in WBool; N : out FZ) is
ffa_ch4_ffacalc.kv     58    begin
ffa_ch4_ffacalc.kv     59       FZ_Clear(N);
ffa_ch4_ffacalc.kv     60       FZ_Set_Head(N, V);
ffa_ch4_ffacalc.kv     61    end WBool_To_FZ;
ffa_ch4_ffacalc.kv     62    
ffa_ch4_ffacalc.kv     63    
ffa_ch2_logicals.kv    64    -- First word of N := Source
ffa_ch2_logicals.kv    65    procedure FZ_Set_Head(N : out FZ; Source : in Word) is
ffa_ch2_logicals.kv    66    begin
ffa_ch2_logicals.kv    67       N(N'First) := Source;
ffa_ch2_logicals.kv    68    end FZ_Set_Head;
ffa_ch2_logicals.kv    69    
ffa_ch2_logicals.kv    70    
ffa_ch2_logicals.kv    71    -- First word of N
ffa_ch2_logicals.kv    72    function FZ_Get_Head(N : in FZ) return Word is
ffa_ch2_logicals.kv    73    begin
ffa_ch2_logicals.kv    74       return N(N'First);
ffa_ch2_logicals.kv    75    end FZ_Get_Head;
ffa_ch2_logicals.kv    76    
ffa_ch2_logicals.kv    77    
ffa_ch2_logicals.kv    78    -- Exchange X and Y
ffa_ch2_logicals.kv    79    procedure FZ_Swap(X : in out FZ; Y : in out FZ) is
ffa_ch3_shifts.kv      80       T : FZ(X'Range);
ffa_ch2_logicals.kv    81    begin
ffa_ch2_logicals.kv    82       T := X;
ffa_ch2_logicals.kv    83       X := Y;
ffa_ch2_logicals.kv    84       Y := T;
ffa_ch2_logicals.kv    85    end FZ_Swap;
ffa_ch2_logicals.kv    86    
ffa_ch2_logicals.kv    87    
ffa_ch2_logicals.kv    88    -- Constant-time MUX: Sel = 0: Result := X; Sel = 1: Result := Y
ffa_ch2_logicals.kv    89    procedure FZ_Mux(X : in FZ; Y : in FZ; Result : out FZ; Sel : in WBool) is
ffa_ch2_logicals.kv    90    begin
ffa_ch2_logicals.kv    91       for i in X'Range loop
ffa_ch2_logicals.kv    92          Result(i) := W_Mux(X(i), Y(i), Sel);
ffa_ch2_logicals.kv    93       end loop;
ffa_ch2_logicals.kv    94    end FZ_Mux;
ffa_ch2_logicals.kv    95    
ffa_ch2_logicals.kv    96 end FZ_Basic;