Motorola DSP56300, Руководство пользователя

Страница: 19 / 112

2-4 Optimizing DSP56300/DSP56600 Applications MOTOROLA
Data Operations
Using the Dual Data Paths
Parallel moves are also restricted in their use of registers as source
and destination to a part of the Data ALU registers. The register
options available for XY Addressing are listed in
Table 2-2 . Any
register in the X field column can appear with any register in the Y
column, with the obvious exception of updating the same
accumulator from both the X and Y fields.
The register options available for long addressing are listed in
Table 2-3 .
Note: Some syntax combinations of the accumulators differ only in
shifting/limiting (if the register is the source) or implicit
register updates (if they are destination). For example,
compare “A10” with “A”. In the “AB” and “BA”
combinations, each accumulator has same behavior as a
regular move, such as:
move a, x:(r0)+.
Transfer Data ALU Register TFR
Test Accumulators TST
Table 2-2 Registers Used in Parallel XY Moves
X Field Y Field Comments
X0 Y0
X1 Y1
A
A
As source: undergoes shifting and
limiting
As destination: A2/B2 sign
extended, A0/B0 zero filled
B
B
Table 2-1 Parallel Move Instructions (Continued)
Instruction Mnemonic
Relevant
Opcode variants