Analog Devices ADSP-BF53x Blackfin Reference page 527

Also See
RND (Round to
Special Applications
Typically, use the Add/Subtract – Prescale Up instruction to provide an
IEEE 1180–compliant 2D 8x8 inverse discrete cosine transform.
ADSP-BF53x/BF56x Blackfin Processor Programming Reference
Half-Word), Add/Subtract – Prescale
Arithmetic Operations
Down, Add
15-15