TIdDecoderBinHex4.Decode Method

Decodes BinHex 4.0-encoded data.

Pascal

procedure Decode(
    const AIn: string; 
    const AStartPos: Integer = 1; 
    const ABytes: Integer = -1
); override;

Parameters

Parameters	Description
AIn	Encoded data for the operation.
AStartPos	Starting position in the encoded data.
ABytes	Number of bytes to be decoded.

Description

Decode is an overridden method in TIdDecoderBinHex4. Decode performs decoding for the BinHex data in AIn starting at the position indicated in AStartPos and continuing for the number of bytes indicated in ABytes.

The value in AStartPos starts at 1 (one).

ABytes can contain any value from 1 to the length of the input data in AIn. -1 indicates that all values in AIn will be decoded.

Decode examines the values in AIn to determine when the Colon delimiter (ASCII decimal 58) is encountered at the start or end of the BinHex 4.0-encoded data. Decode raises the EIdMissingColon exception when the Colon delimiter characters are not found in the BinHex-encoded data.

After values in AIn have been decoded, Decode checks for run-length encoding in the decoded content by looking for the RLE marker (ASCII Decimal 144 Hex 90). Run-length encoded values are restored to their non-RLE-encoded values.

Decode removes the BinHex header included at the beginning of the content, including the following data types:

Data Type	Description
Byte	Length of the FileName (1..63)
Bytes	FileName bytes (up to "Length" bytes)
Byte	Version
Long	Type
Long	Creator
Word	Flags (And $F800)
Long	Length of Data Fork
Long	Length of Resource Fork
Word	CRC
Bytes	Data Fork ("Data Length" bytes)
Word	CRC
Bytes	Resource Fork ("Rsrc Length" bytes)
Word	CRC

Decode writes the decoded values for the specified content to the stream for the decoder.

Use TIdEncoderBinHex4 to create the values used in the AIn argument.