REM Language: SmallBASIC 0.12.6 (Linux 32-bit)
REM Purpose: A Base64 Encoder/Decoder UNIT.
REM File name: base64.bas
REM Unit name: base64
REM Version: 1.0.1 21/05/2016
REM Author: Christian d'Heureuse; shian (See License below)
' Notes:
' 1. Translated from VBasic to SmallBASIC (shian).
'
' 2. Useful for IMAGE keyword, and for any binary-to-text encoding/decoding.
' Base64 is often used to embed binary data in source code.
'
' 3. Since this is a translated code, I did not add much comments about the
' encoding/decoding method... So for more details about it see:
' https://en.wikipedia.org/wiki/Base64
'
' 4. License:
' - A Base64 Encoder/Decoder. This module is used to encode and decode data
' in Base64 format as described in RFC 1521.
' - Home page: www.source-code.biz.
' - Code from: http://www.source-code.biz/snippets/vbasic/12.htm
' - License: GNU/LGPL (www.gnu.org/licenses/lgpl.html).
' - Copyright 2007: Christian d'Heureuse, Inventec Informatik AG, Switzerland.
' - This module is provided "as is" without warranty of any kind.
'
' -- Start Demo code --- --- --- --- --- --- --- --- --- --- ---
'
' ' ( See also: http://smallbasic.sourceforge.net/?q=comment/1398#comment-1398 )
'
' Import base64 ' (Import from another .bas file)
'
' Const FILE = "SB.png" ' (Change it to any other file name)
'
' ' Example using a "file name":
' s = base64.Encode_Base64(FILE) ' Encode 1-D bytes-array to Base64-string
' a = base64.Decode_Base64(s) ' Decode Base64-string to 1-D bytes-array
'
' i = Image(a) ' Convert 1-D bytes-array to image
' i.Show(10, 10) ' Show image at location (x, y)
' Showpage
'
' ' Example using a file # (opened for input):
' Open FILE For Input As #1
' s = base64.Encode_Base64(1) ' Encode 1-D bytes-array to Base64-string
' Close #1
' a = base64.Decode_Base64(s) ' Decode Base64-string to 1-D bytes-array
'
' i = Image(a) ' Convert 1-D bytes-array to image
' i.Show(30, 30) ' Show image at location (x, y)
' Showpage
'
' ' Example using 1-D bytes-array (a):
' s = base64.Encode_Base64(a) ' Encode 1-D bytes-array to Base64-string
' a = base64.Decode_Base64(s) ' Decode Base64-string to 1-D bytes-array
'
' i = Image(a) ' Convert 1-D bytes-array to image
' i.Show(50, 50) ' Show image at location (x, y)
' Showpage
'
' Pause
'
' -- End Demo code --- --- --- --- --- --- --- --- --- --- --- ---
Unit base64
Export Encode_Base64, Decode_Base64
' Initialize the helper maps (this code executes only once at load time).
Dim Map1(0 To 63)
Dim Map2(0 To 127)
i = 0
' Set Map1
For c = 65 To 90: Map1(i) = c: i++: Next ' Asc("A") To Asc("Z")
For c = 97 To 122: Map1(i) = c: i++: Next ' Asc("a") To Asc("z")
For c = 48 To 57: Map1(i) = c: i++: Next ' Asc("0") To Asc("9")
Map1(i) = 43 : i++ ' Asc("+")
Map1(i) = 47 : i++ ' Asc("/")
' Set Map2
For i = 0 To 127 Do Map2(i) = 255
For i = 0 To 63 Do Map2(Map1(i)) = i
' Encodes a 1-D bytes array (integers) into Base64 format string.
' No blanks or line breaks are inserted.
' Parameters:
' InData 1-D bytes array containing the data bytes to be encoded;
' or, "File_Name" string to load into 1-D bytes array;
' or, File-Number (opened-for-input) to load into 1-D bytes array.
' Returns: a string with the Base64 encoded data (that you can embed in
' your source code).
Func Encode_Base64(InData)
Local Out ' (As Byte)
Local ODataLen, OLen, ILen ' (As Long)
Local ip0, ip, op ' (As Long)
Local i0, i1, i2 ' (As Byte)
Local o0, o1, o2, o3 ' (As Byte)
Local s, i, fn, f ' as SmallBASIC...
If Isarray(InData) Then ' 1-D bytes array (integers) supplied
ILen = Len(InData)
' Make life easier by loading 1-D bytes array from file:
Else
f = Isnumber(InData) ' Set flag to close file
If f Then ' An opened file # (For Input) supplied
fn = InData
Else ' A "filename" supplied
fn = Freefile
Open InData For Input As #fn
Fi
ILen = Lof(fn)
Dim InData(1 To ILen) ' (It's much faster to allocate space first!)
For i = 1 To ILen Do InData(i) = Bgetc(fn)
If Not f Then Close #fn ' (Don't close file if File # supplied)
Fi
If ILen = 0 Then Encode_Base64 = "": Exit Func
ODataLen = (ILen * 4 + 2) \ 3 ' Output length without padding
OLen = ((ILen + 2) \ 3) * 4 ' Output length including padding
Dim Out(0 To OLen - 1)
ip0 = LBound(InData)
' Encode base64 bytes array (See Wikipedia for this...):
While ip < ILen
i0 = InData(ip0 + ip): ip++
If ip < ILen Then i1 = InData(ip0 + ip): ip++ Else i1 = 0
If ip < ILen Then i2 = InData(ip0 + ip): ip++ Else i2 = 0
o0 = i0 \ 4
o1 = ((i0 Band 3) * 0x10) Bor (i1 \ 0x10)
o2 = ((i1 Band 0xF) * 4) Bor (i2 \ 0x40)
o3 = i2 Band 0x3F
Out(op) = Map1(o0): op++
Out(op) = Map1(o1): op++
Out(op) = Iff(op < ODataLen, Map1(o2), 61): op++ ' 61 is Asc("=")
Out(op) = Iff(op < ODataLen, Map1(o3), 61): op++ ' 61 is Asc("=")
Wend
s = "": For i In Out Do s += Chr(i) ' Bytes-to-String
Encode_Base64 = s
End Func
' Decodes a string from Base64 format.
' Parameters
' s a Base64 String to be decoded.
' Returns: a 1-D array containing the decoded data bytes (integers).
Func Decode_Base64(s)
Local IBuf, Out ' (As Byte array)
Local i0, i1, i2, i3 ' (As Byte)
Local b0, b1, b2, b3 ' (As Byte)
Local o0, o1, o2 ' (As Byte)
Local OLen, ip, op ' (As Long)
Local ILen = Len(s) ' (As Long)
Local i ' as SmallBASIC...
If (ILen Mod 4) Or (ILen = 0) Then ' Data error
Throw "Length of Base64 encoded input string is not a multiple of 4."
Fi
Dim IBuf(0 To ILen - 1)
For i = 1 To ILen Do IBuf(i - 1) = Asc(Mid(s, i, 1)) ' String-to-Bytes
While ILen > 0
If IBuf(ILen - 1) <> 61 Then Exit Loop ' 61 is Asc("=")
ILen--
Wend
OLen = (ILen * 3) \ 4
Dim Out(0 To OLen - 1) ' 1-D bytes array
' Decode base64 bytes array (See Wikipedia for this...):
While ip < ILen
i0 = IBuf(ip): ip++
i1 = IBuf(ip): ip++
If ip < ILen Then i2 = IBuf(ip): ip++ Else i2 = 65 ' 65 is Asc("A")
If ip < ILen Then i3 = IBuf(ip): ip++ Else i3 = 65 ' 65 is Asc("A")
If i0 > 127 Or i1 > 127 Or i2 > 127 Or i3 > 127 Then
Throw "Illegal character in Base64 encoded data." ' Data error
Fi
b0 = Map2(i0)
b1 = Map2(i1)
b2 = Map2(i2)
b3 = Map2(i3)
If b0 > 63 Or b1 > 63 Or b2 > 63 Or b3 > 63 Then
Throw "Illegal character in Base64 encoded data." ' Data error
Fi
o0 = (b0 * 4) Bor (b1 \ 0x10)
o1 = ((b1 Band 0xF) * 0x10) Bor (b2 \ 4)
o2 = ((b2 Band 3) * 0x40) Bor b3
Out(op) = o0: op++
If op < OLen Then Out(op) = o1: op++
If op < OLen Then Out(op) = o2: op++
Wend
Decode_Base64 = Out
End Func