AD9613 PN generation


I want to use AD9613 instead of AD9643,and change the HDL code of AD9643 to match AD9613. I have some problems about PN sequence in hdl_2016_R1.

1. in axi_ad9643_pnmon.v   

assign adc_pn_data_in_s = {adc_pn_data_in[13:0], ~adc_data[13], adc_data[12:0]};  

in data sheet, it said that the test data is placed on the output pins, why ~adc_data[13] not adc_data[13]

2  also in axi_ad9643_pnmon.v 

assign adc_pn_data_pn_s = (adc_pn_oos == 1'b0) ? adc_pn_data_pn :

                            { adc_pn_data_pn[29], adc_pn_data_in[27:14], 

                             adc_pn_data_pn[14], adc_pn_data_in[13: 0]};

can I chang to  assign adc_pn_data_pn_s = (adc_pn_oos == 1'b0) ? adc_pn_data_pn :                                                       { adc_pn_data_pn[29:27], adc_pn_data_in[23:12],

                              adc_pn_data_pn[14:12], adc_pn_data_in[11: 0]};

to match ad9613

Thought the code, I think AD9643 generate 15 pn code once, send 14 LSB, right ?

AD9613 generates 15 pn code ,send 12 lsb, or generates 12 pn code send 12 code?