vb 压缩算法

Attribute VB_Name = "Comp_LZW_Predefined"


'Option Compare Database
Option Explicit

'This is a 2 run method

Private MaxChars As Long
Private TempStream() As Byte
Private OutStream() As Byte
Private OutPos As Long
Private OutByteBuf As Integer
Private OutBitCount As Integer
Private ReadBitPos As Integer

Private Dict() As String        'the dictionaries
Private DictPos As Integer      'the position to store the next characters
Private SearchPos() As Long
Private SpeedSearch() As Long
Private ActDict As Integer      'actual dictionary
Private maxCharLenght As Byte   'Maximum stringlength in de dictionary
Private maxDictDeep As Long     'maximum stored words per dictionary
Private TotBitDeep As Integer   'total bitlength per character
Private MaxBitDeep As Integer
Private minBitDeep As Integer
Private StartDict As Long       'startposition of de dictionary
Private NewBitLengt As Long
Private EscapeCode As Long
Private WaitForLessBits As Long

'The next varariable is used to detect the kind of ascii's used
'0 = all ascii
'1 = 2 ascii determen the range that is used
'<=127 following codes are used
'>127 following codes are not used
Private DictCode As Integer
Private DictChars(127) As Byte


Public Sub Compress_LZWPre(FileArray() As Byte)
    Dim ByteValue As Byte
    Dim TempByte As Long
    Dim ExtraBits As Integer
    Dim DictStr As String
    Dim NewStr As String
    Dim CompPos As Long
    Dim DictVal As Long
    Dim DictPosit As Long
    Dim DictPositOld As Long
    Dim FilePos As Long
    Dim FileLenght As Long
    Dim BitLengthCount As Integer
    Dim Temp As Long
    Dim MostUsed1 As Integer
    Dim MostUsed2 As Integer
    Dim MostCount1 As Long
    Dim MostCount2 As Long
    Dim MinCount As Long
    Dim CharCount(255) As Long