All of the AXI4 channels follow the same fundamental rules:
- All TDATA and TUSER fields are packed in little endian format. Bit 0 of a sub-field is aligned to the same side as bit 0 of TDATA or TUSER.
- All TDATA and TUSER vectors are multiples of 8 bits. After all fields in a TDATA or TUSER vector are concatenated, the overall vector is padded to bring it up to an 8 bit boundary.