Source code in the icon programming language

procedure main()
every i := 2097152 | 2097151 | 1 | 127 | 128 | 589723405834 | 165 | 256 do 
   write(image(i)," = ",string2hex(v := uint2vlq(i))," = ",vlq2uint(v))
end

procedure vlq2uint(s)    #: decode a variable length quantity 
   if *s > 0 then {
      i := 0
      s ? while h := ord(move(1)) do {
         if (pos(0) & h > 128) | (not pos(0) & h < 128) then fail
         i := 128 * i + h % 128
         }
      return i
      }
end

procedure uint2vlq(i,c)  #: encode a whole number as a variable length quantity
   if "integer" == type(-1 < i) then 
      return if i = 0 then 
         char((/c := 0)) | ""
      else          
         uint2vlq(i/128,1) || char((i % 128) + ((/c := 0) | 128) )
end

procedure string2hex(s)  #: convert a string to hex
   h := ""
   every i := ord(!s) do 
      h ||:= "0123456789abcdef"[i/16+1] || "0123456789abcdef"[i%16+1]
   return h
end