Shift right operations by the Nios II processor on Arria V
and Stratix V devices might produce incorrect results in certain
configurations. This issue can occur when the hardware multiplication
type is set to DSP Block. When the Nios II processor
SRA instruction on
a negative value, the result is shifted, but not sign-extended.
This issue is a result of how the DSP block wrapper is implemented for 28nm devices.
You can fix this issue in the Quartus II software v12.0 by applying a patch. To obtain the patch, file a service request at mySupport, referring to solution ID number rd07032012_629.