CPU_TO_LE64
dest_qword &= ~(CPU_TO_LE64(mask)); /* get the bits not changing */
dest_qword |= CPU_TO_LE64(src_qword); /* add in the new bits */
src_qword &= CPU_TO_LE64(mask);
src_qword &= ~(CPU_TO_LE64(mask));
dest_qword &= ~(CPU_TO_LE64(mask)); /* get the bits not changing */
dest_qword |= CPU_TO_LE64(src_qword); /* add in the new bits */