Difference between revisions of "Delphi compatible LCG Random"
From Lazarus wiki
Jump to navigationJump to search| Line 14: | Line 14: | ||
interface | interface | ||
| − | function | + | function LCGRandom: extended; overload;inline; |
| − | function | + | function LCGRandom(const range:longint):longint;overload;inline; |
implementation | implementation | ||
| Line 25: | Line 25: | ||
end; | end; | ||
| − | function | + | function LCGRandom: extended; overload;inline; |
begin | begin | ||
Result := IM * 2.32830643653870e-10; | Result := IM * 2.32830643653870e-10; | ||
end; | end; | ||
| − | function | + | function LCGRandom(const range:longint):longint;overload;inline; |
begin | begin | ||
Result := IM * range shr 32; | Result := IM * range shr 32; | ||
Revision as of 17:37, 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 LCGRandom: extended; overload;inline;
function LCGRandom(const range:longint):longint;overload;inline;
implementation
function IM:cardinal;inline;
begin
RandSeed := RandSeed * 134775813 + 1;
Result := RandSeed;
end;
function LCGRandom: extended; overload;inline;
begin
Result := IM * 2.32830643653870e-10;
end;
function LCGRandom(const range:longint):longint;overload;inline;
begin
Result := IM * range shr 32;
end;
end.