FDSXF#
Format: FDSXF dest, source.
Phase0: FDSXF FT0, S0{.NEG}{.ABS}
Phase1: FDSXF FT1, S3{.NEG}{.ABS}
Phase2: -
Description: Gradient in x direction, one source
If (Pix0, Pix1) D = Pix1 - Pix0
If (Pix2, Pix3) D = Pix3 - Pix2
(DX 11 version)