Difference between revisions of "Delphi compatible LCG Random"
From Free Pascal wiki
Jump to navigationJump to search| Line 2: | Line 2: | ||
Many Freepascal programmers also maintain sourcecode in Delphi.<br> | Many Freepascal programmers also maintain sourcecode in Delphi.<br> | ||
Even if you have moved to Freepascal from Delphi you may have data that relies on Delphi's Random.<br> | Even if you have moved to Freepascal from Delphi you may have data that relies on Delphi's Random.<br> | ||
| − | Here are | + | Here are cross-platform functions that generate Delphi-identical pseudo-random numbers: |
<syntaxhighlight> | <syntaxhighlight> | ||
unit drandom; | unit drandom; | ||
Revision as of 15:30, 26 March 2017
Delphi compatible random numbers
Many Freepascal programmers also maintain sourcecode in Delphi.
Even if you have moved to Freepascal from Delphi you may have data that relies on Delphi's Random.
Here are cross-platform functions that generate Delphi-identical pseudo-random numbers:
unit drandom;
// Delphi compatible LCG random number generator routines for Freepascal.
// (c)2017, Thaddy de Koning. Use as you like
// Algorithm, Delphi multiplier and increment taken from:
// https://en.wikipedia.org/wiki/Linear_congruential_generator
// The default Delphi RandomSeed is determined as zero.
{$mode objfpc}
interface
function DelphiRandom: Double; overload;inline;
function DelphiRandom(range:integer):integer;overload;inline;
implementation
function IM:dword;inline;
begin
RandSeed := RandSeed * 134775813 + 1;
Result := RandSeed;
end;
function DelphiRandom: Double; overload;inline;
begin
Result := IM * 2.32830643653870e-10;
end;
function DelphiRandom(range:integer):integer;overload;inline;
begin
Result := IM * range shr 32;
end;
end.