The AES engine can accept up to 64 bytes of input data (16 32-bit words) and can hold up to 64 bytes of output data at a time. This is configured with bits 12-13 and 14-15 in AES_CNT (see above).
The input data for the AES crypto operation is written to AES_WRFIFO, the output data is read from AES_RDFIFO.
The input data for the AES crypto operation is written to AES_WRFIFO, the output data is read from AES_RDFIFO.