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REM *************************************************
REM * Original Author: Randy Charles Morin
REM * Author's Website: http://www.kbcafe.com
REM *
REM * Ported from C++ to DBP
REM *
REM * Converted By: Phaelax
REM * Website: http://cca-software.com
REM *************************************************



test$ = "This is a TEST!"
print test$
encoded$ = encode64$(test$)
print encoded$
print decode64$(encoded$)

suspend for key


rem Encodes a string to base64
rem returns an encoded string
function encode64$(encode as string)
   b1 as byte
   b2 as byte
   b3 as byte
   value$ = ""

   if len(encode) = 0 then exitfunction value$

   for i=1 to len(encode) step 3

      b1 = 0
      b2 = 0
      b3 = 0

      b1 = asc(mid$(encode,i))

      if (i+1 <= len(encode)) then b2 = asc(mid$(encode,i+1))
      if (i+2 <= len(encode)) then b3 = asc(mid$(encode,i+2))

      b4 as byte
      b5 as byte
      b6 as byte
      b7 as byte

      b4 = b1>>2
      b5 = ((b1&&0x3)<<4) || (b2>>4)
      b6 = ((b2&&0xf)<<2) || (b3>>6)
      b7 = b3&&0x3f

      value$ = value$ + encodeByte$(b4)
      value$ = value$ + encodeByte$(b5)

      if i+1 <= len(encode)
         value$ = value$ + encodeByte$(b6)
      else
         value$ = value$ + "="
      endif

      if i+2 <= len(encode)
         value$ = value$ + encodeByte$(b7)
      else
         value$ = value$ + "="
      endif

      if i mod 76 = 0
         value$ = value$ + chr$(13)+chr$(10)
      endif

   next i

endfunction value$


rem Decodes a string to base64
rem returns a decoded string
function decode64$(decode as string)
   b1 as byte
   b2 as byte
   b3 as byte
   value$ = ""
   temp$ = ""

   for j = 1 to len(decode)
      if isBase64(mid$(decode,j)) then temp$ = temp$ + mid$(decode,j)
   next j

   if len(temp$) = 0 then exitfunction value$

   for i = 1 to len(temp$) step 4
      c1$ = "A"
      c2$ = "A"
      c3$ = "A"
      c4$ = "A"

      c1$ = mid$(temp$, i)

      if i+1 <= len(temp$) then c2$ = mid$(temp$,i+1)
      if i+2 <= len(temp$) then c3$ = mid$(temp$,i+2)
      if i+3 <= len(temp$) then c4$ = mid$(temp$,i+3)

      b1 as byte
      b2 as byte
      b3 as byte
      b4 as byte

      b1 = decodeChar(c1$)
      b2 = decodeChar(c2$)
      b3 = decodeChar(c3$)
      b4 = decodeChar(c4$)

      value$ = value$ + chr$(b1<<2 || b2>>4)

      if c3$ <> "=" then value$ = value$ + chr$(((b2&&0xf)<<4) || (b3>>2))
      if c4$ <> "=" then value$ = value$ + chr$(((b3&&0x3)<<6) || b4)
   next i

endfunction value$



rem private helper function
rem technically, its a 6-bit pattern
rem with the two higher bits as 0
rem byte as input
rem returns a character
function encodeByte$(b as byte)
   if b < 26 then exitfunction chr$(asc("A")+b)
   if b < 52 then exitfunction chr$(asc("a")+(b-26))
   if b < 62 then exitfunction chr$(asc("0")+(b-52))
   if b = 62 then exitfunction "+"
endfunction "/"


rem private helper function
rem character as input
rem returns byte value of decoded char
function decodeChar(c as string)
   if c >= "A" and c <= "Z"
      v = asc(c)-asc("A")
      exitfunction v
   endif
   if c >= "a" and c <= "z"
      v = asc(c)-asc("a")+26
      exitfunction v
   endif
   if c >= "0" and c <= "9"
      v = asc(c)-asc("0")+52
      exitfunction v
   endif
   if c = "+" then exitfunction 62
endfunction 63


rem private helper function
rem checks if the character is a
rem valid base64 character
rem returns true or false
function isBase64(c as string)
   if c >= "A" and c <= "Z" then exitfunction 1
   if c >= "a" and c <= "z" then exitfunction 1
   if c >= "0" and c <= "9" then exitfunction 1
   if c = "+" then exitfunction 1
   if c = "/" then exitfunction 1
   if c = "=" then exitfunction 1
endfunction 0