Programming Model
MSC8144E Reference Manual, Rev. 3
Freescale Semiconductor
26-127
26.5.8.3 AESU Data Size Register (AESUDSR)
The AESU Data Size Register stores the number of bits in the final message block. Acceptable
sizes vary depending on the AES mode selected. In ECB and CBC modes, the message
processed by the AESU must be a multiple of 128 bits; the AESU does not automatically pad
messages out to 128-bit blocks. In CCM and CTR modes, data size must be a multiple of 8 bits.
In XOR mode the data size must be a multiple of 256 bits (32 bytes). If an improper data size is
written, a data size error is generated. Only the lowest 3, 7, or 8 bits of the Data Size Register are
checked to determine if there is a data size error. Since all upper bits are ignored, the entire
message length (in bits) can be written to this register. This register is cleared when the AESU is
reset or reinitialized. Writing to this register signals the AESU to start processing data from the
input FIFO as soon as it is available. If the value of data size is modified during processing, a
context error is generated.
AESUDSR
AESU Data Size Register
Offset 0xC4010
Bits
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
48
Field
—
Type
R/W
Reset 0x0000
Bits
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
Field
—
Type
R/W
Reset
0x0000
Bits 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Field
—
Type
R/W
Reset 0x0000
Bits
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Field
—
Data Size
Type
R/W
Reset 0x0000
Table 26-43. DEUDSR Field Descriptions
Name
Reset
Description
—
63–12
0
Reserved. Write to zero for future compatibility.
Data Size
11–0
0
Data Size
Stores the number of bits in the final message block. The required value is mode dependent:
• ECB and CBC modes: Multiple of 128 bits.
• CCM and CTR modes: Multiple of 8 bits.
• XOR mode: Multiple of 256 bits (32 bytes).
Note:
Entry of an improper data size results in the setting of AESUISR[DSE] to indicate a data size
error. Modification of the data size during processing results in the setting of AESUISR[CE]
bit to indicate a context error.
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 ...