GNIDA.mediana.lookup_opcode C# (CSharp) Method

        static UInt32 lookup_opcode(long offset, byte table, ref OPCODE_DESCRIPTOR opcode_descr, INTERNAL_DATA idata)
        {
            byte max;
            byte opcode;
            UInt32 res;

            res = 0;
            //opcode_descr = NULL;
            do
            {
            opcode = assembly.Image.ReadBytes(offset, 1)[0];

            opcode >>= tables[table].shift;
            opcode &= tables[table].mask;
            opcode -= tables[table].min;
            //It looks strange, but I want that table descriptors contain
            // "real" values.
            max = (byte)(tables[table].max - tables[table].min);
            if (opcode > max)
            {
            idata.severe_err = ERRS.ERR_BADCODE;
            break;
            }

            if (res > MAX_INSTRUCTION_LEN)
            {
            idata.severe_err = ERRS.ERR_TOO_LONG;
            break;
            }

            if ( (tables[table].props & TBL_PROP_MODRM)==0 )
            {
            res++;
            offset++;
            }

            if ((tables[table].opcodes[opcode].groups & GRP_SWITCH)!=0)
            {
            table = (byte)tables[table].opcodes[opcode].props;// &0xFF;
            continue;
            }
            break;
            }
            while(true);

            if (idata.severe_err == ERRS.ERR_OK)
            opcode_descr = tables[table].opcodes[opcode];

            return res;
        }