hiraethbbs / renegade.random

Random functions using the current os's built in methods.

Free Pascal Random Bytes

This file is a part of Renegade 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.

From the Free Pascal website :

Free Pascal is a 32, 64 and 16 bit professional Pascal compiler. It can target many processor architectures: Intel x86 (including 8086), AMD64/x86-64, PowerPC, PowerPC64, SPARC, ARM, AArch64, MIPS and the JVM. Supported operating systems include Linux, FreeBSD, Haiku, Mac OS X/iOS/iPhoneSimulator/Darwin, DOS (16 and 32 bit), Win32, Win64, WinCE, OS/2, MorphOS, Nintendo GBA, Nintendo DS, Nintendo Wii, Android, AIX and AROS. Additionally, support for the Motorola 68k architecture is available in the development versions.

Usage

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

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

uses
  Renegade.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 Random.RandomInterface;

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

uses
  Renegade.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 trys to use syscall(SYS_getrandom) if that fails it reads from /dev/urandom and then /dev/random before failing.
• On Windows systems TRandom uses Windows built in CryptGenRandom function.
• On BSD systems TRandom uses arc4random_buf. (Done : read from arc4random_buf this is the same on Mac systems, because Mac = FreeBSD)

TRandom will fall back on Free Pascal's Random function which uses the Mersenne Twister algorithm to get random bytes.