A.D.A. Amiga Demoscene Archive

Amiga Demoscene Archive Forum / Coding / Restoring the system

Author	Message
ZEROblue Member	#1 - Posted: 4 Aug 2008 23:59 Reply Quote I'm trying an alternative method for restoring the system after taking the hardware. Instead of peeking in graphics library to get the current view and copper list I am just leaving all of this up to the RemakeDisplay call. The code below restores the system perfectly almost every time, and in fact I can also leave the restoration of DMACON out because I've seen that this is done via RemakeDisplay. However occasionally it happens that the view is not restored and I end up in AmigaOS with no changes whatsoever to the display related HW registers. Does anyone know why this happens? dmacon = $96 dmaconr = $2 intena = $9a intenar = $1c OpenLibrary = -552 CloseLibrary = -414 LoadView = -222 WaitTOF = -270 RemakeDisplay = -384 move.l 4.w, a6 lea graphicslib, a1 moveq #33, d0 jsr OpenLibrary(a6) move.l d0, a6 move.l d0, -(sp) sub.l a1, a1 jsr LoadView(a6) jsr WaitTOF(a6) lea $dff000, a6 move.w dmaconr(a6), d0 move.w intenar(a6), d1 move.w #$7ff, dmacon(a6) move.w #$7fff, intena(a6) movem.w d0-d1, -(sp) move.l #copperlist, cop1lch(a6) move.w d0, copjmp1(a6) move.w #%1000001010000000, dmacon(a6) wait btst #6, $bfe001 bne.s wait move.w #$7ff, dmacon(a6) move.w #$7fff, intena(a6) movem.w (sp)+, d0-d1 or.w #$8040, d0 or.w #$c000, d1 move.w d0, dmacon(a6) move.w d1, intena(a6) move.l 4.w, a6 lea intuitionlib, a1 moveq #33, d0 jsr OpenLibrary(a6) move.l d0, a6 jsr RemakeDisplay(a6) move.l a6, a1 move.l 4.w, a6 jsr CloseLibrary(a6) move.l (sp)+, a1 jsr CloseLibrary(a6) moveq #0, d0 rts intuitionlib dc.b "intuition.library", 0 graphicslib dc.b "graphics.library", 0 section dat, data_c copperlist dc.l $8001ff00, $01800800 dc.l $9001ff00, $01800080 dc.l $a001ff00, $01800008 dc.l $b001ff00, $01800000 dc.l -2
Cefa Member	#2 - Posted: 14 Aug 2008 10:36 - Edited Reply Quote You could try posting in amiga.org some of them seems to know alot about the amiga OS. There is one guy there named Piru he is the author of the program blizkick. He seems to be know (based on his previous post in amiga.org) alot about the Amiga OS.
ZEROblue Member	#3 - Posted: 15 Aug 2008 01:00 Reply Quote Thanks, Cefa For anyone's interest, I noticed some days ago that the code above fails when you hold the right mouse button down while calling RemakeDisplay. For some reason some of the display registers will then be set to that of an NTSC display, and some registers will remain untouched.
z5_ Member	#4 - Posted: 15 Aug 2008 21:47 Reply Quote The coders are probably all on the beach right now, enjoying the summer. Out of interest, ZEROblue, why are you trying a different method for restoring the system?
ZEROblue Member	#5 - Posted: 16 Aug 2008 11:47 - Edited Reply Quote I've never actually had any problems with the "classic" method, but because I've never looked at RTG on the Amiga and the display related registers around $1C0 to $1E0, I have no idea how these work and how they might affect your display. It seemed to me that peeking around in the Graphics Library base and basically just changing DMA and bitplane controls was not an intended method from the beginning, and that it could somehow fail on an RTG configuration. I just reasoned that letting the AmigaOS take care of as much as possible was the safer bet of always getting a correct display output from the basic hardware and having the previous view restored correctly. If anyone is well read up on how these things work and can still my curiosity, don't hesitate to enlighten me :)
Crumb Member	#6 - Posted: 19 Aug 2008 12:05 Reply Quote @ZEROblue Take a look at Piru's init code: URL Perhaps you could simply open a public screen, perform a forbid() at the beginning and at the end perform a permit() and close the public screen.

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