iTextSharp.text.pdf.PdfReader.ASCII85Decode C# (CSharp) Метод

        public static byte[] ASCII85Decode(byte[] inp) {
            MemoryStream outp = new MemoryStream();
            int state = 0;
            int[] chn = new int[5];
            for (int k = 0; k < inp.Length; ++k) {
                int ch = inp[k] & 0xff;
                if (ch == '~')
                    break;
                if (PRTokeniser.IsWhitespace(ch))
                    continue;
                if (ch == 'z' && state == 0) {
                    outp.WriteByte(0);
                    outp.WriteByte(0);
                    outp.WriteByte(0);
                    outp.WriteByte(0);
                    continue;
                }
                if (ch < '!' || ch > 'u')
                    throw new ArgumentException("Illegal character in ASCII85Decode.");
                chn[state] = ch - '!';
                ++state;
                if (state == 5) {
                    state = 0;
                    int rx = 0;
                    for (int j = 0; j < 5; ++j)
                        rx = rx * 85 + chn[j];
                    outp.WriteByte((byte)(rx >> 24));
                    outp.WriteByte((byte)(rx >> 16));
                    outp.WriteByte((byte)(rx >> 8));
                    outp.WriteByte((byte)rx);
                }
            }
            int r = 0;
            // We'll ignore the next two lines for the sake of perpetuating broken PDFs
//            if (state == 1)
//                throw new ArgumentException("Illegal length in ASCII85Decode.");
            if (state == 2) {
                r = chn[0] * 85 * 85 * 85 * 85 + chn[1] * 85 * 85 * 85 + 85 * 85 * 85  + 85 * 85 + 85;
                outp.WriteByte((byte)(r >> 24));
            }
            else if (state == 3) {
                r = chn[0] * 85 * 85 * 85 * 85 + chn[1] * 85 * 85 * 85  + chn[2] * 85 * 85 + 85 * 85 + 85;
                outp.WriteByte((byte)(r >> 24));
                outp.WriteByte((byte)(r >> 16));
            }
            else if (state == 4) {
                r = chn[0] * 85 * 85 * 85 * 85 + chn[1] * 85 * 85 * 85  + chn[2] * 85 * 85  + chn[3] * 85 + 85;
                outp.WriteByte((byte)(r >> 24));
                outp.WriteByte((byte)(r >> 16));
                outp.WriteByte((byte)(r >> 8));
            }
            return outp.ToArray();
        }
        

            public byte[] Decode(byte[] b, PdfName filterName, PdfObject decodeParams, PdfDictionary streamDictionary)
            {
                MemoryStream outS = EnableMemoryLimitsAwareHandler(streamDictionary);

                b = PdfReader.ASCII85Decode(b, outS);
                return(b);
            }