Analog Devices ADSP-BF53x Blackfin Reference page 218

Addressing With the AAU
LENGTH = 11
BASE ADDRESS = 0X0
MODIFIER = 4
0X0 1
0X1
0X2
0X3
0X4
2
0X5
0X6
0X7
0X8 3
0X9
0XA
THE COLUMNS ABOVE SHOW THE SEQUENCE IN ORDER OF LOCATIONS ACCESSED IN ONE PASS.
THE SEQUENCE REPEATS ON SUBSEQUENT PASSES.
Figure 5-3. Circular Data Buffers
As seen in Figure
DAG outputs the I-register value on the address bus, then modifies the
address by adding the modify value.
• If the updated index value is within the buffer length, the DAG
writes the value to the I-register.
• If the updated index value exceeds the buffer length, the DAG sub-
tracts (for a positive modify value) or adds (for a negative modify
value) the L-register value before writing the updated index value
to the I-register.
5-14 ADSP-BF53x/BF56x Blackfin Processor Programming Reference
0X0
0X1 4
0X2
0X3
0X4
0X5 5
0X6
0X7
0X8
0X9
6
0XA
5-3, on the first post-modify access to the buffer, the
0X0 0X0
0X1 0X1
0X2 7 0X2
0X3 0X3
0X4 0X4
0X5 0X5
0X6 8 0X6
0X7 0X7
0X8 0X8
0X9 0X9
0XA 0XA
9
10
11