you showed the function ineed but you didnt show the paramters you passing to it if num_bytes_to_insert == 0 then the loop never get perform
casue the next line
Code:
unsigned int remaining_bytes = static_cast<unsigned int>(num_bytes_to_insert & BITMASK_FOR_SIGNIFICANT_TWO_BITS);
will be zero!

Code:
unsigned int num_bytes_to_insert;
this paramter is never initialzied and its zero!
so like i said the loop never performed hence pointers not moving.

Cheers