1 files changed, 100 insertions, 0 deletions
diff --git a/kroete.inc b/kroete.inc
new file mode 100644
index 0000000..8f2d939
--- /dev/null
+++ b/kroete.inc
@@ -0,0 +1,100 @@
+;	es:si	pointer to data
+;	bx	== 0 forward  != 0 backward
+kroete:
+	mov	fs,[window_seg_w]
+	mov	ax,[window_seg_r]
+	or	ax,ax
+	jnz	sul1
+	mov	ax,[window_seg_w]
+sul1:	mov	gs,ax
+	mov	di,[cs:screen_width]
+	shr	di,1
+	imul	di,[cs:pixel_bytes]
+	mov	ax,[cs:screen_height]
+	shr	ax,1
+	mul	word [cs:screen_line_len]
+	add	di,ax
+	adc	dx,byte 0
+	mov	ax,dx
+	call	set_win
+	call	kr_getpixel
+	or	bx,bx
+	jnz	sul3
+	lea	bp,[si+16384]
+sul:	mov	bl,[es:si]
+	rol	bl,2
+	call	doit
+	rol	bl,2
+	call	doit
+	rol	bl,2
+	call	doit
+	rol	bl,2
+	call	doit
+	inc	si
+	cmp	si,bp
+	jnz	sul
+	call	kr_putpixel
+      	ret
+sul3:	lea	bp,[si-1]
+	add	si,16383
+sul4:	mov	bl,[es:si]
+	xor	bl,0xaa
+	call	doit
+	ror	bl,2
+	call	doit
+	ror	bl,2
+	call	doit
+	ror	bl,2
+	call	doit
+	dec	si
+	cmp	si,bp
+	jnz	sul4
+	call	kr_putpixel
+	ret
+doit:
+	push	ecx
+	call	kr_getpixel
+	mov	edx,ecx
+	pop	ecx
+	call	kr_putpixel
+	mov	ecx,edx
+	mov	dl,bl
+	and	dl,3
+	jnz	doit1
+	sub	di,[cs:pixel_bytes]
+	jnc	doit4
+doit5:	sbb	al,0
+	jmp	set_win
+doit1:	dec	dl
+	jnz	doit2
+	sub	di,[cs:screen_line_len]
+	jc	doit5
+doit4:	ret
+doit2:	dec	dl
+	jnz	doit3
+	add	di,[cs:pixel_bytes]
+	jnc	doit4
+doit6:	adc	al,0
+	jmp	set_win
+doit3:  add	di,[cs:screen_line_len]
+	jc	doit6
+	ret
+
+kr_getpixel:
+	cmp byte [cs:pixel_bytes],1
+	ja kr_getpixel_10
+	mov cl,[fs:di]
+	ret
+kr_getpixel_10:
+	mov cx,[fs:di]
+	ret
+
+kr_putpixel:
+	cmp byte [cs:pixel_bytes],1
+	ja kr_putpixel_10
+	mov [gs:di],cl
+	ret
+kr_putpixel_10:
+	mov [gs:di],cx
+	ret
+