Stefan Thoolen .nl | VB6 Function Database

Attribute VB_Name = "modChangeEndian"
' These functions are downloaded from:
' http://www.stefanthoolen.nl/archive/vb6-functions/
' 
' You may freely distribute this file but please leave all comments, including this one, in it.
' 
' @Author Stefan Thoolen <mail@stefanthoolen.nl>

Option Explicit

''
' Completes a string by adding zero characters to the front
' @param    string  value       The input string
' @param    integer length      The length the return value must be
' @param    string  character   Optional, the character that should be used for filling, default: "0"
' @author   Stefan Thoolen <mail@stefanthoolen.nl>
Public Function zerofill(ByVal value As String, ByVal length As Integer, Optional ByVal character = "0") As String
    If Len(value) >= length Then zerofill = value: Exit Function
    Dim i As Integer
    Do
        value = character & value
    Loop While Len(value) < length
    zerofill = value
End Function

''
' Makes a binary string from an integer number
' Same syntax as the PHP function 'decbin'
' See also: http://www.php.net/manual/en/function.decbin.php
' @param    Integer number          The decimal value
' @return   String                  A binary presentation of the number (ex.: 00100111)
' @author   Stefan Thoolen <mail@stefanthoolen.nl>
Public Function decbin(ByVal number As Integer) As String
    Dim retval As String
    Do Until number = 0
        If (number Mod 2) Then retval = "1" & retval Else retval = "0" & retval
        number = number \ 2
    Loop
    decbin = retval
End Function

''
' Makes an integer number from a binary string
' Same syntax as the PHP function 'bindec'
' See also: http://www.php.net/manual/en/function.bindec.php
' @param    String  binary_string   The binary string (ex.: 00100111)
' @return   Integer                 A decimal presentation of the binary value
' @author   Stefan Thoolen <mail@stefanthoolen.nl>
Public Function bindec(binary_string As String) As Long
    Dim i As Integer, pos As Integer, ret As Long
    For i = 1 To Len(binary_string)
        pos = Len(binary_string) - i
        If Mid(binary_string, pos + 1, 1) = "1" Then ret = ret + (2 ^ (i - 1))
    Next i
    bindec = ret
End Function

''
' When reading a binary file in another endian, this function can convert multiple bytes to a valid number
' @param    string  inp         The bytes as string
' @return   variant             The actual number
' @author   Stefan Thoolen <mail@stefanthoolen.nl>
Public Function change_endian(ByVal inp As String, Optional ByVal reverse As Boolean = False) As Variant
    If Len(inp) = 0 Then change_endian = 0: Exit Function
    
    Dim i As Integer, s As String
    If reverse Then
        For i = 1 To Len(inp)
            s = s & zerofill(decbin(Asc(Mid(inp, i, 1))), 8)
        Next i
    Else
        For i = Len(inp) To 1 Step -1
            s = s & zerofill(decbin(Asc(Mid(inp, i, 1))), 8)
        Next i
    End If
    
    change_endian = bindec(s)
End Function
Visual Basic 6 function "change_endian"

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