🚀 go-pugleaf

Is there an error in the Postscript Language Reference regarding ASCII-85 Encoding or am I just fundamentally messed up?

According to the spec as I read it, if your input data ends with n bytes, where n is less than 4, you pad the data with 4 - n zeros to create the base 256 4-tupple. You then encode as normal (convert to base 85, add 33 to each byte to make it printable), but only output the first n + 1 bytes.

This presumes that you could encode an 8 bit byte with only two base 85 digits. While this is true, it does not hold if you encode it "normally".

For instance, consider an input file consisting of a single digit: "."
The ascii value for . (period) is 46. Our resulting 4-tupple of 46,0,0,0 gives us an integral value of 771751936. Coding this in base-85 gives us the sequence of 14,66,56,74,46 or /cYGO after applying the addition of '!' (ascii 33) to each digit to get it in the printable range. According to the spec this would be output simply as /c followed by ~> (n+1 digits plus EOD marker). Subsequent decoding of this, however, gives us a value of 45. You could encode 46 using two digits as /d, but no where in the spec can I see reference to doing this. You could also handle this in the decoder, recognizing /c as 46 rather than the calculated 45. Since it isn't clearly specified, you have a 50/50 chance or either fixing the error, or compounding it.

Is my understanding correct or can anyone tell me the error that I am making? Thanks.