EU Specific Data Packet Descriptors
MCF548x Reference Manual, Rev. 3
Freescale Semiconductor 22-77

22.14.3 MDEU Mode Options and Data Packet Descriptors

The MDEU mode options, shown in Figure 22-48, contains 8 bits which are used to program the MDEU.

The mode options are cleared when the MDEU is reset or re-initialized. Setting a reserved mode bit will

generate a data error. If the mode options are modified during processing, a context error will be generated.

Table 22-65 describes MDEU mode option fields.

0x20600010 CBC Triple DES Decrypt
0x20100010 ECB Single DES Encrypt
0x20000010 ECB Single DES Decrypt
0x20300010 ECB Triple DES Encrypt
0x20200010 ECB Triple DES Decrypt
76543210
Field CONT INT HMAC PD ALG
Reset 0000_0000
Loc PMODE/SMODE Field in DPD Header

Figure 22-48. MDEU Mode Options

Table 22-65. MDEU Mode Option Field Descriptions

Bits Name Description
7 CONT Continue. Used during HMAC/HASH processing when the data to be hashed is spread
across multiple descriptors.
0 Don’t Continue- operate the MDEU in auto completion mode.
1 Preserve context to operate the MDEU in continuation mode.
6–5 — Reserved
4 INT Initialization. Cause an algorithm-specific initialization of the digest registers. Most
operations will require this bit to be set. Only static operations that are continuing from a
known intermediate hash value would not initialize the registers.
0 Do not initialize
1 Initialize the selected algorithm’s starting registers
3 HMAC HMAC enable. Identifies the hash operation to execute:
0 Perform standard hash
1 Perform HMAC operation. This requires a key and key length information.

Table 22-64. Typical Header Values Final Static DEU Descriptor Format (Continued)

Header Value E/C S/T E/D