64 lines
2.7 KiB
Markdown
64 lines
2.7 KiB
Markdown
# Free Pascal Random Bytes
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This file is a part of [Renegade BBS](http://renegade.cc "Renegade BBS").
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This will only work with [Free Pascal](http://freepascal.org "Free Pascal") version 3+. I Think [namespacing](http://wiki.freepascal.org/FPC_New_Features_3.0#Delphi-like_namespaces_units "Namespaces") 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](http://scummvm.org/ "ScummVM is a program which allows you to run certain classic graphical point-and-click adventure games, provided you already have their data files.")_.
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##### From the Free Pascal website :
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_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._
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### Usage
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Make sure to include ```{$mode objfpc}{$H+}``` in your header or compile with ```-S2 -Sh``` switches.
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```pascal
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Program RandomTest;
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{$mode objfpc}{$H+}
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uses
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Renegade.Random,
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Classes;
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var
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R : TRandom;
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S : AnsiString;
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T : TBytes;
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begin
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R := TRandom.Init;
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S := R.GetString(22);
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T := R.GetBytes(22);
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R.Free;
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```
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You can also use a custom random generator. It needs to implement Renegade.Random.RandomInterface;
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```pascal
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Program RandomTest;
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{$mode objfpc}{$H+}
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uses
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Renegade.Random,
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MyCustomGenerator,
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Classes;
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var
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R : TRandom;
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S : AnsiString;
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T : TBytes;
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begin
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R := TRandom.Init;
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R.RandomGenerator := MyCustomGenerator.Create;
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S := R.GetString(22);
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T := R.GetBytes(22);
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R.SetDefaultGenerator; // To get back to the default Generator.
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S := R.GetString(22);
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T := R.GetBytes(22);
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R.Free;
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```
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* On Linux systems TRandom uses SYS_getrandom.
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* On Windows systems TRandom uses Windows built in [CryptGenRandom](https://msdn.microsoft.com/en-us/library/windows/desktop/aa379942(v=vs.85).aspx "CryptGenRandom") function.
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* On BSD systems TRandom uses [arc4random_buf](https://www.freebsd.org/cgi/man.cgi?query=arc4random_buf&sektion=3 "arc4random_buf") this is the same on Mac systems, because Mac = FreeBSD).
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TRandom will fall back on reading from /dev/urandom, then /dev/random, and finally Free Pascal's [Random](http://www.freepascal.org/docs-html/rtl/system/random.html "Random") function which uses the [Mersenne Twister](https://en.wikipedia.org/wiki/Mersenne_Twister "Mersenne Twister") algorithm to get random bytes.
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