Analog Devices ADSP-21261 SHARC Hardware Reference Manual page 194

DAG Operations
• If M is positive:
I = I
new
I = I
new
• If M is negative:
I = I
new
I = I
new
The DAGs use all four types of DAG registers for addressing circular buf-
fers. These registers operate as follows for circular buffering.
• The index (
the address bus.
• The modify (
or negative) that the DAG adds to the
memory access. The
DAG as the
The modify value can also be an immediate value instead of an
register. The size of the modify value, whether from an
immediate, must be less than the length (
buffer.
• The length (
address range that the DAG circulates the
register must be positive and cannot have a value greater than
31
2 – 1. If an
is disabled.
• The DAG compares the base (
register, to the modified
ter is loaded, the corresponding
with the same value. When
can read the
4-16
+ M if I + M < buffer base (start of buffer)
old old
+ M – L if I + M
old old
+ M if I + M
old old
+ M + L if I
old old
) register contains the value that the DAG outputs on
I
) register contains the post-modify amount (positive
M
register can be any
M
register and does not have to have the same number.
I
) register sets the size of the circular buffer and the
L
register's value is zero, its circular buffer operation
L
I
and registers independently.
B I
ADSP-2126x SHARC Processor Hardware Reference

buffer base + length (end of buffer)

buffer base (start of buffer)
+ M < buffer base (start of buffer)
register at the end of each
I
register in the same
M
register) of the circular
L
register through. The
I
) register, or the
B
value after each access. When the
register is simultaneously loaded
I
is loaded, is not changed. Programs
I B
M
register or
M
L
register plus the
B L
regis-
B