Data commit

Task/Pseudo-random-numbers-PCG32/Delphi/pseudo-random-numbers-pcg32.delphi

@@ -0,0 +1,120 @@
+program PCG32_test;
+
+{$APPTYPE CONSOLE}
+uses
+  System.SysUtils,
+  Velthuis.BigIntegers,
+  System.Generics.Collections;
+
+type
+  TPCG32 = class
+  public
+    FState: BigInteger;
+    FInc: BigInteger;
+    mask64: BigInteger;
+    mask32: BigInteger;
+    k: BigInteger;
+    constructor Create(seedState, seedSequence: BigInteger); overload;
+    constructor Create(); overload;
+    destructor Destroy; override;
+    procedure Seed(seed_state, seed_sequence: BigInteger);
+    function NextInt(): BigInteger;
+    function NextIntRange(size: Integer): TArray<BigInteger>;
+    function NextFloat(): Extended;
+  end;
+
+{ TPCG32 }
+
+constructor TPCG32.Create(seedState, seedSequence: BigInteger);
+begin
+  Create();
+  Seed(seedState, seedSequence);
+end;
+
+constructor TPCG32.Create;
+begin
+  k := '6364136223846793005';
+  mask64 := (BigInteger(1) shl 64) - 1;
+  mask32 := (BigInteger(1) shl 32) - 1;
+  FState := 0;
+  FInc := 0;
+end;
+
+destructor TPCG32.Destroy;
+begin
+
+  inherited;
+end;
+
+function TPCG32.NextFloat: Extended;
+begin
+  Result := (NextInt.AsExtended / (BigInteger(1) shl 32).AsExtended);
+end;
+
+function TPCG32.NextInt(): BigInteger;
+var
+  old, xorshifted, rot, answer: BigInteger;
+begin
+  old := FState;
+  FState := ((old * k) + FInc) and mask64;
+  xorshifted := (((old shr 18) xor old) shr 27) and mask32;
+  rot := (old shr 59) and mask32;
+  answer := (xorshifted shr rot.AsInteger) or (xorshifted shl ((-rot) and
+    BigInteger(31)).AsInteger);
+  Result := answer and mask32;
+end;
+
+function TPCG32.NextIntRange(size: Integer): TArray<BigInteger>;
+var
+  i: Integer;
+begin
+  SetLength(Result, size);
+  if size = 0 then
+    exit;
+
+  for i := 0 to size - 1 do
+    Result[i] := NextInt;
+end;
+
+procedure TPCG32.Seed(seed_state, seed_sequence: BigInteger);
+begin
+  FState := 0;
+  FInc := ((seed_sequence shl 1) or 1) and mask64;
+  nextint();
+  Fstate := (Fstate + seed_state);
+  nextint();
+end;
+
+var
+  PCG32: TPCG32;
+  i, key: Integer;
+  count: TDictionary<Integer, Integer>;
+
+begin
+  PCG32 := TPCG32.Create(42, 54);
+
+  for i := 0 to 4 do
+    Writeln(PCG32.NextInt().ToString);
+
+  PCG32.seed(987654321, 1);
+
+  count := TDictionary<Integer, Integer>.Create();
+
+  for i := 1 to 100000 do
+  begin
+    key := Trunc(PCG32.NextFloat * 5);
+    if count.ContainsKey(key) then
+      count[key] := count[key] + 1
+    else
+      count.Add(key, 1);
+  end;
+
+  Writeln(#10'The counts for 100,000 repetitions are:');
+
+  for key in count.Keys do
+    Writeln(key, ' : ', count[key]);
+
+  count.free;
+  PCG32.free;
+  Readln;
+end.