Destination Sign-Extended -->; Destination
extends byte to long word
Attributes: Size = (Long)
Description: Extends a byte in a data register to a long word
by replicating the sign bit to the left. Bit  of the
designated data register is copied to bits [31:16] of that
X Not affected.
N Set if the result is negative. Cleared otherwise.
Z Set if the result is zero. Cleared otherwise.
V Always cleared.
C Always cleared.