Programming Model
MSC8144E Reference Manual, Rev. 3
Freescale Semiconductor
26-123
26.5.7.10 DEU Key Registers (DEUKR[1–3])
The DEU uses three write-only key registers, K1, K2, and K3, to perform encryption and
decryption. In Single DES mode, only K1 may be written. The value written to K1 is
simultaneously written to K3, auto-enabling the DEU for 112-bit Triple DES if the Key Size
Register indicates 2 key 3DES is to be performed (key size = 16 bytes). To operate in 168-bit
Triple DES, K1 must be written first, followed by the write of K2, then K3.
Note:
The DEU key registers are located at the following offsets:
DEUKR1 = Offset 0xC2400.
DEUKR2 = Offset 0xC2408
DEUKR3 = Offset 0xC2410
The Reading any of these memory locations generates an address error interrupt.
26.5.7.11 DEU FIFOs
DEU uses an input FIFO/output FIFO pair to hold data before and after the encryption process.
Normally, the channels control all access to these FIFOs. For core processor-controlled
operation, a write to anywhere in the DEU FIFO address space enqueues data to the DEU input
FIFO, and a read from anywhere in the DEU FIFO address space dequeues data from the DEU
output FIFO.
Writes to the input FIFO go first to a staging register which can be written by byte, 4 bytes, or 8
bytes. When all 8 bytes of the staging register have been written, the entire 8-byte set is
automatically enqueued into the FIFO. If any byte is written twice between enqueues, it causes an
error interrupt of type AE from the EU. Since the DEU data length should always be a multiple of
8 bytes, the last write should complete the 8-byte set. However, if there is any partial data set in
the staging register when the DEU End_of_Message Register is written, the partial data is
automatically padded with zeros to a full 8 bytes and enqueued to the input FIFO.
The output FIFO is readable by byte, 4-byte, or 8-byte accesses. When all 8 bytes of the header
are read, that set is automatically dequeued from the FIFO so that the next 8 bytes (if any)
become available for reading. If any byte is read twice between dequeues, it causes an error
interrupt of type AE from the EU.
Overflows and underflow caused by reading or writing the DEU FIFOs are reflected in the DEU
Interrupt Status Register.
Note:
The DEU FIFOs occupy a memory space in the range defined by offsets
0xC2800–0xC2FFF
Summary of Contents for MSC8144E
Page 1: ...MSC8144E Reference Manual Quad Core Media Signal Processor MSC8144ERM Rev 3 July 2009 ...
Page 48: ...MSC8144E Reference Manual Rev 3 xlviii Freescale Semiconductor ...
Page 86: ...MSC8144E Reference Manual Rev 3 1 38 Freescale Semiconductor Overview ...
Page 168: ...MSC8144E Reference Manual Rev 3 3 60 Freescale Semiconductor External Signals ...
Page 242: ...MSC8144E Reference Manual Rev 3 5 26 Freescale Semiconductor Reset ...
Page 314: ...MSC8144E Reference Manual Rev 3 8 24 Freescale Semiconductor General Configuration Registers ...
Page 414: ...MSC8144E Reference Manual Rev 3 10 14 Freescale Semiconductor MSC8144E SC3400 DSP Subsystem ...
Page 452: ...MSC8144E Reference Manual Rev 3 11 38 Freescale Semiconductor Internal Memory Subsystem ...
Page 520: ...MSC8144E Reference Manual Rev 3 12 68 Freescale Semiconductor DDR SDRAM Memory Controller ...
Page 1070: ...MSC8144E Reference Manual Rev 3 21 28 Freescale Semiconductor Timers ...