Analog Devices ADSP-BF53x Blackfin Reference page 548

Instruction Overview
Required Mode
User & Supervisor
Parallel Issue
The 32-bit versions of this instruction and the 16-bit versions that use
can be issued in parallel with specific other 16-bit instructions. For
Ireg
details, see "Issuing Parallel Instructions" on page
All other 16-bit versions of this instruction cannot be issued in parallel
with other instructions.
Example
a0 -= a1 ;
a0 -= a1 (w32) ;
p3 -= p0 ;
i1 -= m2 ;
Also See
Modify – Increment, Subtract,
Special Applications
Typically, use the Index Register and Pointer Register versions of the
Modify – Decrement instruction to decrement indirect address pointers
for load or store operations.
15-36 ADSP-BF53x/BF56x Blackfin Processor Programming Reference
Shift with Add
20-1.