public FuncPtg(RecordInputStream in) 
{
                       
        //field_1_num_args = data[ offset + 0 ];
        field_2_fnc_index  = in.readShort();
        FunctionMetadata fm = FunctionMetadataRegistry.getFunctionByIndex(field_2_fnc_index);
        if(fm == null) {
            throw new RuntimeException("Invalid built-in function index (" + field_2_fnc_index + ")");
        }
        numParams = fm.getMinParams();
        returnClass = fm.getReturnClassCode();
        paramClass = fm.getParameterClassCodes();
}

Creates new function pointer from a byte array usually called while reading an excel file.

 public FuncPtg(int functionIndex) 
{
        field_2_fnc_index = (short) functionIndex;
        FunctionMetadata fm = FunctionMetadataRegistry.getFunctionByIndex(functionIndex);
        numParams = fm.getMinParams(); // same as max since these are not var-arg funcs
        returnClass = fm.getReturnClassCode();
        paramClass = fm.getParameterClassCodes();
}

 public int getNumberOfOperands() 
{
        return numParams;
}

 public int getSize() 
{
        return SIZE;
}

 public String toString() 
{
        StringBuffer sb = new StringBuffer(64);
        sb.append(getClass().getName()).append(" [");
        sb.append(lookupName(field_2_fnc_index));
        sb.append(" nArgs=").append(numParams);
        sb.append("]");
        return sb.toString();
}

 public  void writeBytes(byte[] array,
    int offset) 
{
        array[offset+0]= (byte) (sid + getPtgClass());
        LittleEndian.putShort(array,offset+1,field_2_fnc_index);
}