Dont understand the meaning of this LOOP (VHDL)

[BlackOps]

I am studying the VHDL code generated by the Peripheral Wizard in EDK 9.1

there is such piece of code:

        for byte_index in 4 to 14 loop
          if ( mst_byte_we(byte_index) = '1' ) then
            mst_reg(byte_index) <= Bus2IP_Data(
                                     (byte_index-(byte_index/(C_DWIDTH/8))*(C_DWIDTH/8))*8 to
                                     (byte_index-(byte_index/(C_DWIDTH/8))*(C_DWIDTH/8))*8+7);
          end if;
        end loop;

C_DWIDTH = 64

for example, if byte_index is 4.. then: (4 - ( ( 4/8 ) * 8 ) ) * 8 = 0, dosnt matter what is value of byte_index, Bus2IP_Data will always have value of [0 to 7] inside...

then why does the wizard not just writes Bus2IP_Data(0 to 7) ?? why is it using such complicated equation? or i am wrong somewhere?

thanks

 

[teddyzhai]

I think, this "user logic" file is just a generic template generated by EDK. It is parametrized.