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Single 16-Bit Operations
In single 16-bit operations, any two 16-bit register halves may be used as
the input to the ALU. An addition, subtraction, or logical operation pro-
duces a 16-bit result that is deposited into an arbitrary destination register
half. ALU0 is used for this operation, because it is the primary resource for
ALU operations.
For example:
R3.H = R1.H + R2.L (NS) ;
adds the 16-bit contents of
low half) and deposits the result in
Dual 16-Bit Operations
In dual 16-bit operations, any two 32-bit registers may be used as the
input to the ALU, considered as pairs of 16-bit operands. An addition,
subtraction, or logical operation produces two 16-bit results that are
deposited into an arbitrary 32-bit destination register. ALU0 is used for
this operation, because it is the primary resource for ALU operations.
For example:
R3 = R1 +|– R2 (S) ;
adds the 16-bit contents of
high half) and deposits the result in
The instruction also subtracts the 16-bit contents of
from the contents of
low half) with saturation (see
ADSP-BF53x/BF56x Blackfin Processor Programming Reference
(
high half) to the contents of
R1.H
R1
R3.H
(
high half) to the contents of
R2.H
R2
R3.H
(
low half) and deposits the result in
R1.L
R1
Figure 2-10 on page
Computational Units
(
high half) with no saturation.
R3
(
high half) with saturation.
R3
(
R2.L
2-39).
(
R2.L
R2
(
R1.H
R1
low half)
R2
(
R3.L
R3
2-27
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