[__arm_]vhcaddq_rot90[_s8]

This instruction performs a complex addition of the first operand with the second operand rotated in the complex plane by the specified amount. A 90 degree rotation of this operand corresponds to a multiplication by a positive imaginary unit, while a 270 degree rotation corresponds to a multiplication by a negative imaginary unit. Even and odd elements of the source vectors are interpreted to be the real and imaginary components, respectively, of a complex number. The result is halved before being written to the destination register.