ÿþ{{

** Base64 decoding/encoding functions v0.1

** by Robert Quattlebaum <darco@deepdarc.com>

** PUBLIC DOMAIN

** 2008-04-18

**

** TODO: Implement this in ASM!

** TODO: Implement encoder!    

}}

PUB inplaceDecode(in_ptr) | out_ptr,i,in,char,size

{{ Decodes a base64 encoded string in-place. Returns the size of the decoded data. }}

  out_ptr:=in_ptr

  size:=0

  repeat

    ifnot BYTE[in_ptr]

      quit

    repeat i from 0 to 3

      repeat while isWhitespace(char:=BYTE[in_ptr++])

      ifnot char

        BYTE[@in][i]:="="

        in_ptr--

        quit

      else

        BYTE[@in][i]:=char

     

    i:=base64_decode_4(@in,out_ptr)

    out_ptr+=i

    size+=i

  while char AND i==3     

  BYTE[out_ptr]:=0

  return size

PRI isWhitespace(char)

  case char

    9..13,32: return TRUE

    other: return FALSE

pri base64_tlu(char) | i

  case char

    "A".."Z": return char-"A"

    "a".."z": return char-"a"+26

    "0".."9": return char-"0"+52

    "+": return 62

    "/": return 63

    other: return 0

PRI base64_decode_4(inptr,outptr) | retVal,i,out

  out:=0

  retVal:=3

  repeat i from 0 to 3

    if(BYTE[inptr][i]=="=")

      case i

        3: retVal:=2

        2: retVal:=1

        1: retVal:=0

        0: retVal:=0

      quit

    out|=\base64_tlu(BYTE[inptr][i])<<((3-i)*6)

  if retVal

    repeat i from 0 to retVal-1

      BYTE[outptr][i]:=BYTE[@out][2-i]

  return retVal

CON

{{

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