66 lines
2.4 KiB
Plaintext
66 lines
2.4 KiB
Plaintext
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Const sBASE_64_CHARACTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/
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' ---------------------------------------
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Function Base64decode(ByVal asContents)
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Dim lsResult
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Dim lnPosition
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Dim lsGroup64, lsGroupBinary
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Dim Char1, Char2, Char3, Char4
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Dim Byte1, Byte2, Byte3
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If Len(asContents) Mod 4 > 0 Then asContents = asContents & String(4 - (Len(asContents) Mod 4), " ")
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lsResult = ""
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For lnPosition = 1 To Len(asContents) Step 4
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lsGroupBinary = ""
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lsGroup64 = Mid(asContents, lnPosition, 4)
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Char1 = InStr(sBASE_64_CHARACTERS, Mid(lsGroup64, 1, 1)) - 1
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Char2 = InStr(sBASE_64_CHARACTERS, Mid(lsGroup64, 2, 1)) - 1
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Char3 = InStr(sBASE_64_CHARACTERS, Mid(lsGroup64, 3, 1)) - 1
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Char4 = InStr(sBASE_64_CHARACTERS, Mid(lsGroup64, 4, 1)) - 1
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Byte1 = Chr(((Char2 And 48) 16) Or (Char1 * 4) And &HFF)
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Byte2 = lsGroupBinary & Chr(((Char3 And 60) 4) Or (Char2 * 16) And &HFF)
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Byte3 = Chr((((Char3 And 3) * 64) And &HFF) Or (Char4 And 63))
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lsGroupBinary = Byte1 & Byte2 & Byte3
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lsResult = lsResult + lsGroupBinary
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Next
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Base64decode = lsResult
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End Function
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' --------------------------------------
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Function Base64encode(ByVal asContents)
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Dim lnPosition
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Dim lsResult
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Dim Char1
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Dim Char2
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Dim Char3
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Dim Char4
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Dim Byte1
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Dim Byte2
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Dim Byte3
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Dim SaveBits1
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Dim SaveBits2
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Dim lsGroupBinary
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Dim lsGroup64
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If Len(asContents) Mod 3 > 0 Then asContents = asContents & String(3 - (Len(asContents) Mod 3), " ")
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lsResult = ""
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For lnPosition = 1 To Len(asContents) Step 3
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lsGroup64 = ""
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lsGroupBinary = Mid(asContents, lnPosition, 3)
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Byte1 = Asc(Mid(lsGroupBinary, 1, 1)): SaveBits1 = Byte1 And 3
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Byte2 = Asc(Mid(lsGroupBinary, 2, 1)): SaveBits2 = Byte2 And 15
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Byte3 = Asc(Mid(lsGroupBinary, 3, 1))
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Char1 = Mid(sBASE_64_CHARACTERS, ((Byte1 And 252) 4) + 1, 1)
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Char2 = Mid(sBASE_64_CHARACTERS, (((Byte2 And 240) 16) Or (SaveBits1 * 16) And &HFF) + 1, 1)
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Char3 = Mid(sBASE_64_CHARACTERS, (((Byte3 And 192) 64) Or (SaveBits2 * 4) And &HFF) + 1, 1)
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Char4 = Mid(sBASE_64_CHARACTERS, (Byte3 And 63) + 1, 1)
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lsGroup64 = Char1 & Char2 & Char3 & Char4
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lsResult = lsResult + lsGroup64
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Next
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Base64encode = lsResult
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End Function
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