Olive.Random/README.md

Free Pascal Random Bytes

This file is a part of Olive BBS.

This will only work with Free Pascal version 3+. I Think namespacing is a good idea, and FPC 3+ is not hard to get your hands on for any platform. In fact, I believe its the most cross platform program that I have ever found, including ScummVM.

Usage

Make sure to include {$mode objfpc}{$H+} in your header or compile with -S2 -Sh switches.

Program RandomTest;
{$mode objfpc}{$H+}

uses
  Olive.Random,
  Classes;

var
  R : TRandom;
  S : AnsiString;
  T : TBytes;
begin
  R := TRandom.Init;
  S := R.GetString(22);
  T := R.GetBytes(22);
  R.Free;

You can also use a custom random generator. It needs to implement Olive.Random.RandomInterface;

Program RandomTest;
{$mode objfpc}{$H+}

uses
  Olive.Random,
  MyCustomGenerator,
  Classes;

var
  R : TRandom;
  S : AnsiString;
  T : TBytes;
begin
  R := TRandom.Init;
  R.RandomGenerator := MyCustomGenerator.Create;
  S := R.GetString(22);
  T := R.GetBytes(22);
  R.SetDefaultGenerator; // To get back to the default Generator.
  S := R.GetString(22);
  T := R.GetBytes(22);
  R.Free;

• On Linux systems TRandom uses SYS_getrandom.
• On Windows systems TRandom uses Windows built in CryptGenRandom function.
• On BSD systems TRandom uses arc4random_buf this is the same on Mac systems, because Mac = FreeBSD).

TRandom will fall back on reading from /dev/urandom, then /dev/random, and finally Free Pascal's Random function which uses the Mersenne Twister algorithm to get random bytes.