Analog Devices ADSP-BF53x Blackfin Reference page 680

Instruction Overview
Also See
DISALGNEXCPT,
Special Applications
Use the Quad 8-Bit Subtract-Absolute-Accumulate instruction for
block-based video motion estimation algorithms using block Sum of
Absolute Difference (SAD) calculations to measure distortion.
18-40 ADSP-BF53x/BF56x Blackfin Processor Programming Reference
Load Data Register