AutoHotkey Community

Drop(string,list,delim="") {                    ; Drop entries of list from string
   IfEqual delim,, SetEnv delim,`,
   Loop Parse, list, %delim%
      StringReplace string, string, %A_LoopField%,,All
   Return String
}

Ascii85Decode(ByRef data, code, ByRef len) {
   code := drop(code,"<~, ,`f,`n,`r,`t,`v,~>")  ; Ignore white space, terminators
   case = %A_StringCaseSense%
   StringCaseSense On                           ; Z != z
   StringReplace, code, code, z, !!!!!, All
   StringCaseSense %case%                       ; Restore StringCaseSense

   m := Mod(StrLen(code),5) - (Mod(StrLen(code),5)>0) ; 12345 -> x1230
   len := (StrLen(code)//5)*4 + m
   VarSetCapacity(data,len,0)
   p := &data
   x = 0
   Loop Parse, code                             ; For each code char
      If Mod(A_Index,5) = 0 {                   ; After 5 chars seen
         x := x*85 + Asc(A_LoopField)-33
         Loop 4 {                               ; Poke 4 Big Endian bytes
            DllCall("RtlFillMemory",UInt,p, UInt,1, UChar,x>>(32-8*A_Index))
            p++                                 ; Advance data pointer
         }
         x = 0
      }
      Else
         x := x*85 + Asc(A_LoopField)-33        ; Collect base 85 digits
   x := (x+1) * 85**(4-m) ; omitted code chars -> 85+33, carry stops at trailing 0's of x
   Loop %m%  {                                  ; Slack
      DllCall("RtlFillMemory",UInt,p, UInt,1, UChar,x>>(32-8*A_Index))
      p++
   }
}
Ascii85Encode(ByRef code, ByRef data, n=0) {
   If n not between 1 and % VarSetCapacity(data)
      n := StrLen(data)                         ; If no \0 in data, can omit n
   x = 0
   code = <~                                    ; Terminator
   Loop %n% {
      x += *(&data+A_Index-1) << (24-8*((A_Index-1)&3)) ; Collect 4 Big Endian bytes
      If !(A_Index & 3) {                       ; Mod(index,4) = 0
         IfEqual x,0, SetEnv code,%code%z       ; 0000 -> "z"
         Else Loop 5                            ; Base 85 conversion (32-bit arithmetic)
            code := code  Chr(33+Mod(x//85**(5-A_Index),85))
         x = 0                                  ; Restart byte collection
      }
   }
   If (n & 3)                                   ; Mod(n,4) > 0
      Loop % (n&3)+1                            ; Slack
         code := code  Chr(33+Mod(x//85**(5-A_Index),85))
   code = %code%~>                              ; Terminator
}

Loop 7 {
   data(d,A_Index,len)     ; set: binary d, len in bytes
   Ascii85Encode(c,d,len)  ; set: string c
   d := Bin2hex(d,len)
   Ascii85Decode(b,c,len)  ; set: binary b, len in bytes
   b := Bin2hex(b,len)
   MsgBox % "data:`n" d "`n`ndecoded:`n" b "`n`nencoded:`n" c "`n`nstandard:`n" code(A_Index) "`n`n OK: " (b=d) (c=code(A_Index))
}
ExitApp

data(ByRef d, i, ByRef l) {
   IfEqual i,1, {
      l = 1
      d = .
   }
   Else IfEqual i,2, {
      l = 2
      d = ..
   }
   Else IfEqual i,3, {
      l = 3
      Hex2Bin(d,"ffffff")
   }
   Else IfEqual i,4, {
      l = 4
      d = ....
   }
   Else IfEqual i,5, {
      l = 5
      Hex2Bin(d,"123456789A")
   }
   Else IfEqual i,6, {
      l = 6
      Hex2Bin(d,"000000000001")
   }
   Else IfEqual i,7, {
      l = 269
      d =
( Join
Man is distinguished, not only by his reason, but by this singular passion from other animals,
 which is a lust of the mind, that by a perseverance of delight in the continued and
 indefatigable generation of knowledge, exceeds the short vehemence of any carnal pleasure.
)
   }
}

code(i) {
   IfEqual i,1, Return      "<~/c~>"
   Else IfEqual i,2, Return "<~/hR~>"
   Else IfEqual i,3, Return "<~s8W*~>"
   Else IfEqual i,4, Return "<~/hSb/~>"
   Else IfEqual i,5, Return "<~&I<X6RK~>"
   Else IfEqual i,6, Return "<~z!!*~>"
   Else IfEqual i,7, Return,           ; " --> "", ` --> ``
( Join LTrim
"<~9jqo^BlbD-BleB1DJ+*+F(f,q/0JhKF<GL>Cj@.4Gp$d7F!,L7@<6@)/0JDEF<G%<+EV:2F!,
 O<DJ+*.@<*K0@<6L(Df-\0Ec5e;DffZ(EZee.Bl.9pF""AGXBPCsi+DGm>@3BB/F*&OCAfu2/AKY
 i(DIb:@FD,*)+C]U=@3BN#EcYf8ATD3s@q?d$AftVqCh[NqF<G:8+EV:.+Cf>-FD5W8ARlolDIa
 l(DId<j@<?3r@:F%a+D58'ATD4$Bl@l3De:,-DJs``8ARoFb/0JMK@qB4^F!,R<AKZ&-DfTqBG%G
 >uD.RTpAKYo'+CT/5+Cei#DII?(E,9)oF*2M7/c~>"
)
}

Bin2Hex(ByRef b, n=0)            ; n bytes binary data -> stream of 2-digit hex
{                                ; n = 0: all (SetCapacity can be larger than used!)
   format = %A_FormatInteger%    ; save original integer format
   SetFormat Integer, Hex        ; for converting bytes to hex

   m := VarSetCapacity(b)
   If n not between 1 and %m%    ; invalid length -> all allocated
       n = %m%
   Loop %n%
      h := h 256+*(&b+A_Index-1) ; concatenate  0x1xx
   StringReplace h, h, 0x1,,All  ; remove every 0x1

   SetFormat Integer, %format%   ; restore original format
   Return h
}

Hex2Bin(ByRef bin, hex) {        ; Write hex as binary to bin
   VarSetCapacity(bin, StrLen(hex)//2)
   Loop Parse, hex
      If (A_Index & 1)           ; Odd index
         x = 0x%A_LoopField%     ; 1st hex digit of a Byte
      Else
         DllCall("RtlFillMemory",UInt,&bin+A_Index//2-1, UInt,1, UChar,x A_LoopField)
}