_SpriteFlipVert

;-------------------------------------------------------------------------------
_SpriteFlipVert:
; Flip an array vertically about the center horizontal axis
; Arguments:
;  __frame_arg0 : Pointer to 2D byte array input
;  __frame_arg1 : Pointer to 2D byte array output
;  __frame_arg2 : Width
;  __frame_arg3 : Height
; Returns:
;  __frame_arg0 : Pointer to 2D array output
	ld	iy,0
	add	iy,sp
	xor	a,a
	sub	a,(iy+9)
	ld	(_FlipVertDelta_ASM),a \.r
	neg
	ld	(_FlipVertWidth_ASM),a \.r
	ld	l,(iy+12)
	dec	l
	ld	h,a
	mlt	hl
	ld	de,(iy+3)
	add	hl,de
	ld	de,(iy+6)
	push	de
_FlipVertWidth_ASM =$+1
_:	ld	bc,0
	ldir
_FlipVertDelta_ASM =$+1
	ld	bc,-1
	add	hl,bc
	add	hl,bc
	dec	a
	jr	nz,-_
	pop	hl
	ret