Helper.TBytes.md

Helper.TBytes

GetSize, SetSize, Size

function GetSize(): Integer;
procedure SetSize(aSize: Integer);
property Size: Integer read GetSize write SetSize;

• Function GetSize returns size of a byte's array,
• Procedure SetSize changes size of a byte's array to aSize bytes,
• Property Size allows to get or set size of byte array.

Sample:

var
  bytes: TBytes;
begin
  bytes := [1, 2, 3, 4, 5];
  writeln(bytes.GetSize);  // 5
  bytes.SetSize(20);
  writeln(bytes.GetSize);  // 20
  bytes.Size := 28;
  writeln(bytes.Size);     // 28
end;

Load, Save and initialize

procedure LoadFromStream(const aStream: TStream);
procedure LoadFromFile(const aFileName: string);
procedure SaveToStream(const aStream: TStream);
procedure SaveToFile(const aFileName: string);
procedure InitialiseFromBase64String(const aBase64Str: String);

• Procedures LoadFromStream and LoadFromFile allows to populate an array of bytes with data from a file or from a stream,
• Procedures SaveToStream and SaveToFile allows to write an array of bytes in a stream or in a file,
• Procedure InitialiseFromBase64String encodes provided string aBase64Str to an array of bytes using Base64 encoding algorithm.

Sample:

var
  bytes: TBytes;
  memorystream: TMemoryStream;
begin
  bytes := [1, 2, 3, 4, 5];
  memorystream:= TMemoryStream.Create();
  bytes.SaveToFile('numbers.dat');
  bytes := [6, 7];
  bytes.SaveToStream(memorystream);
  bytes.InitialiseFromBase64String('U2FtcGxlIHRleHQ=');
  writeln(BytesToUft8String(bytes));   // 'Sample text'
  bytes.LoadFromFile('numbers.dat');
  writeln(BytesToText(bytes));         // [1, 2, 3, 4, 5]
  memorystream.Position := 0;
  bytes.LoadFromStream(memorystream);
  writeln(BytesToText(bytes));         // [6, 7]
  memorystream.Free;
end;

Block readers

function GetSectorAsHex(aIndex: Integer = 0;  aLength: Integer = 100): string;
function GetSectorAsString(aIndex: Integer = 0;  aLength: Integer = 100): string;
function GetWord(aIndex: Integer = 0): Word;
function GetReverseWord(aIndex: Integer = 0): Word;
function GetLongWord(aIndex: Integer = 0): LongWord;
function GetReverseLongWord(aIndex: Integer = 0): LongWord;
function SubBytes(aIndex, aLength: Integer): TBytes;

• Function GetSectorAsHex reads block of bytes starting at aIndex position with length aLength bytes (default length is equal to 100 bytes or less if size of byte's array is smaller) and converts read block to a text of a hex values separated with spaces,
• Function GetSectorAsString reads block of bytes from the array starting at aIndex position with length aLength bytes and converts each byte into Unicode character,
• Function GetWord reads two bytes at position aIndex position and converts them into word number (0..65535) using little-endian order (first byte is less significant) and function GetReverseWord is using big-endian order,
• Functions GetLongWord and GetReverseLongWord are similar, but read 4 bytes
• Function SubBytes returns sub-block (array of bytes) starting at aIndex position with length aLength bytes

Sample:

var
  bytes: TBytes;
begin
  bytes := [0, 0, 15, 16, $A0, 255, 0, 0];
  writeln(bytes.GetSectorAsHex(2, 4));        // '0F 10 A0 FF'
  bytes := GivenPNGImageAsBytes;
  writeln(bytes.GetSectorAsString(1, 3));  // 'PNG'
  bytes := [0, ,0, 2, 0, 0, 0, 255];
  writeln(bytes.GetLongWord(2));             //  2
  bytes := [255, ,255, 0, 0, 0, 3, 255];
  writeln(bytes.GetReverseLongWord(2));      //  3
  bytes := [255, 255, 16, 0, 255, 255, 255];
  writeln(bytes.SubBytes(2,2).GetWord(0));   // 16
end;

Compare

function IsEqual(const aBytes: TBytes): boolean;

Sample:

var
  bytes1, bytes2: TBytes;
begin
  bytes1 := [0, 255, 0];
  bytes2 := [0, 255];
  writeln(bytes1.IsEqual(bytes2));                // False;
  writeln(bytes1.SubBytes(0,2).IsEqual(bytes2));  // True;

Misc utility functions

function CreateStream: TMemoryStream;
function GenerateBase64Code(aLineLength: Integer = 68): string;
function GetSectorCRC32(aIndex: Integer; aLength: Integer): LongWord;

• Function CreateStream creates new TMemoryStream object and stores byte array. Method is not taking ownership of the stream memory and code which is calling that method should "Free" returned stream memory,
• Function GenerateBase64Code converts a byte's array to a text string encoded using the Base64 algorithm,
• Function GetSectorCRC32 calculates check sum of the byte's array using the CRC32 algorithm.

Sample:

  // TODO: Add sample

ZLib compression

procedure DecompressFromStream(aCompressedStream: TStream);
procedure CompressToStream(aStream: TStream);

• Procedure DecompressFromStream decompress content od the stream aCompressedStream using ZLib library. Stream has to contain a valid ZIP's compressed data,
• Procedure CompressToStream compress an array of bytes using ZLib library (ZIP format) and saves results in aStream stream.

Sample:

  // TODO: Add sample