TIDA-00771 BLDC drive firmware questions

Hi, I'm reading the firmware of TIDA00771.

I found that the SPI is implemented with four IO ports, not the SPI module in MSP430G2553, why?

Moreover, the readregister function is as below:

uint16_t ReadRegister(uint8_t address)
{
uint16_t reading;

reading = ReadOnce(address); //once

delay_1us(1);

reading = ReadOnce(address); //twice

return reading;
}

why do we need to read the register twice?

And in main.c, there is only "ReadRegister(0x01)", it makes no sense because the "reading" result is not given to any variable. I think it should be

"faulttype= ReadRegister(0x01)" for example.

Thanks.