Merge pull request #11 from paweld/gus

improvement of the rng function

Author: gcarreno

generator/Common/generate.common.pas

@@ -17,6 +17,7 @@ interface
 
   TGenerator = class(TObject)
   private
+    rndState: Array [0..1] of Cardinal;
     FInputFile: String;
     FOutPutFile: String;
     FLineCount: Int64;
@@ -52,7 +53,7 @@ implementation
 ;
 
 const
-  cSeed: LongInt = 46668267; // '1BRC' in ASCII
+  cSeed = 46668267; // '1BRC' in ASCII
   linesPercent = 10;
   stationsCapacity = 50000;
   chunkBatch = 10000;
@@ -160,17 +161,15 @@ function TGenerator.GenerateProgressBar(APBPosition, APBMax, APBWIdth, AFileSize
 end;
 
 function TGenerator.Rng1brc(Range: longint): longint;
-const
-  state: Array [0..1] of DWord = (46668267, 7266);
 var
-  s0, s1, s2: DWord;
+  s0, s1, s2: Cardinal;
 begin
-  s0 := state[0];
-  s1 := state[1] xor s0;
-  s2 := RolDWord(s1 * 3, 5) * 7;
+  s0 := rndState[0];
+  s1 := rndState[1] xor s0;
+  s2 := ((s1 * 3) xor 5) * 7;
   Result := longint(Int64(s2 * range) shr 32);
-  state[0] := s2;
-  state[1] := s0 xor (s1 shl 9);
+  rndState[0] := s2;
+  rndState[1] := s0 xor (s1 shl 9);
 end;
 
 procedure TGenerator.Generate;
@@ -186,10 +185,9 @@ procedure TGenerator.Generate;
   chunkCount, chunkLen, stationsCount, temperaturesCount: Integer;
   start: TDateTime;
 begin
-  // Randomize sets this variable depending on the current time
-  // We just set it to our own value
-  RandSeed := cSeed;
-
+  //random init
+  rndState[0] := cSeed;
+  rndState[1] := 7266;
   // Build list of station names
   BuildStationNames;