iTextSharp.text.pdf.codec.TIFFFaxDecoder.NextNBits C# (CSharp) Метод

        private int NextNBits(int bitsToGet) {
            byte b, next, next2next;
            int l = data.Length - 1;
            int bp = this.bytePointer;
            
            if (fillOrder == 1) {
                b = data[bp];
                
                if (bp == l) {
                    next = 0x00;
                    next2next = 0x00;
                } else if ((bp + 1) == l) {
                    next = data[bp + 1];
                    next2next = 0x00;
                } else {
                    next = data[bp + 1];
                    next2next = data[bp + 2];
                }
            } else if (fillOrder == 2) {
                b = flipTable[data[bp] & 0xff];
                
                if (bp == l) {
                    next = 0x00;
                    next2next = 0x00;
                } else if ((bp + 1) == l) {
                    next = flipTable[data[bp + 1] & 0xff];
                    next2next = 0x00;
                } else {
                    next = flipTable[data[bp + 1] & 0xff];
                    next2next = flipTable[data[bp + 2] & 0xff];
                }
            } else {
                throw new Exception("TIFF_FILL_ORDER tag must be either 1 or 2.");
            }
            
            int bitsLeft = 8 - bitPointer;
            int bitsFromNextByte = bitsToGet - bitsLeft;
            int bitsFromNext2NextByte = 0;
            if (bitsFromNextByte > 8) {
                bitsFromNext2NextByte = bitsFromNextByte - 8;
                bitsFromNextByte = 8;
            }
            
            bytePointer++;
            
            int i1 = (b & table1[bitsLeft]) << (bitsToGet - bitsLeft);
            int i2 = (next & table2[bitsFromNextByte]) >> (8 - bitsFromNextByte);
            
            int i3 = 0;
            if (bitsFromNext2NextByte != 0) {
                i2 <<= bitsFromNext2NextByte;
                i3 = (next2next & table2[bitsFromNext2NextByte]) >>
                (8 - bitsFromNext2NextByte);
                i2 |= i3;
                bytePointer++;
                bitPointer = bitsFromNext2NextByte;
            } else {
                if (bitsFromNextByte == 8) {
                    bitPointer = 0;
                    bytePointer++;
                } else {
                    bitPointer = bitsFromNextByte;
                }
            }
            
            int i = i1 | i2;
            return i;
        }