Difference between revisions of "Delphi compatible LCG Random"
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Here are cross-platform functions that generate Delphi-identical pseudo-random numbers: | Here are cross-platform functions that generate Delphi-identical pseudo-random numbers: | ||
<syntaxhighlight> | <syntaxhighlight> | ||
− | unit | + | unit lcgrandom; |
// Delphi compatible LCG random number generator routines for Freepascal. | // Delphi compatible LCG random number generator routines for Freepascal. | ||
// (c)2017, Thaddy de Koning. Use as you like | // (c)2017, Thaddy de Koning. Use as you like |
Revision as of 17:38, 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 lcgrandom;
// 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.