BOOSTXL-POSMGR: T-format encoder functions and communication protocol

Hi experts,

When I was doing the experiment about the encoder, I couldn't understand the meaning of some TI codes,mainly including PM_tformat_receiveData () function and PM_tformat_setupCommand（）function ：

The main questions are as follows:

1.How to calculate the bitIndex and wordNo values?

.

uint16_t PM_tformat_receiveData(uint16_t tformatDataID)
{
    uint32_t len, bitIndex, wordNo;
    uint16_t word1;

    word1  = 1;

    switch(tformatDataID)
    {
      case (PM_TFORMAT_DATAID2):
            len = 8;

            bitIndex = 13;
            wordNo = 1;
            tformatData.controlField = tformat_getBits (len, wordNo, bitIndex);

            wordNo = wordNo + (10 + (16 - bitIndex) ) / 16;
            bitIndex = 16 - ((10 + (16 - bitIndex)) % 16) ;
            tformatData.statusField = tformat_getBits (len, wordNo, bitIndex);

            wordNo = wordNo + (10 + (16 - bitIndex) ) / 16;
            bitIndex = 16 - ((10 + (16 - bitIndex)) % 16) ;
            tformatData.dataField0 = tformat_getBits (len, wordNo, bitIndex);

            wordNo = wordNo + (10 + (16 - bitIndex) ) / 16;
            bitIndex = 16 - ((10 + (16 - bitIndex)) % 16) ;
            tformatData.crc = tformat_getBits (len, wordNo, bitIndex);
            
} 

2.What does 0X903F mean here?How is it calculated?

Best regards

Johnson Alanl