AN2492 Freescale Semiconductor / Motorola, AN2492 Datasheet - Page 7

• Manufacturer Part Number: AN2492
• Description: MPC184 Descriptor Programmers Guide--PCI View
• Manufacturer: Freescale Semiconductor / Motorola

Table 4 describes the DEU mode register signals.
4.3 AFEU Mode Register
The AFEU mode register contains 3 bits which are used to program the AFEU, as shown in Figure 7. It also
reflects the value of burst size, which is loaded by the crypto-channel during normal operation with the
MPC184 as an initiator. Burst size is not relevant to target mode operations, where an external host pushes
and pulls data from the execution units.
The mode register is cleared when the AFEU is reset or re-initialized. Setting a reserved mode bit will
generate a data error. If the mode register is modified during processing, a context error will be generated.
MOTOROLA
31:11
10:8
Bits
Reset
Reset
7:3
Field
Field
Addr
Addr
2
1
0
R/W
R/W
Encrypt/decrypt If set, DEU operates the encryption algorithm; if not set, DEU operates the decryption
31
31
Triple/single
CBC/ECB
Burst size
Signal
DES
—
—
MPC184 Descriptor Programmer’s Guide— PCI View
Reserved
processed with a single key/IV. The DEU signals to the crypto-channel that a ‘burst size’
amount of data is available to be pushed to or pulled from the FIFO.
Note: The inclusion of this field in the DEU mode register is to avoid confusing a user who
may read this register in debug mode. Burst size should not be written directly to the DEU.
Reserved
codebook mode.
0 ECB mode
1 CBC mode
If set, DEU operates the triple DES algorithm; if not set, DEU operates the single DES
algorithm.
0 Single DES
1 Triple DES
algorithm.
0 Perform decryption
1 Perform encryption
The MPC184 implements flow control to allow larger than FIFO sized blocks of data to be
If set, DEU operates in cipher-block-chaining mode. If not set, DEU operates in electronic
Freescale Semiconductor, Inc.
Reserved
For More Information On This Product,
0
Table 4. DEU Mode Register Signals
Figure 6. DEU Mode Register
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DEU 0x0A000
DEU 0x0A004
Reserved
11
R/W
R/W
0
Burst Size
10
Description
0
8
7
Reserved
0
Execution Unit Mode Data
3
CE
2
0
TS
0
1
ED
0
0
0
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