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