From 973a724eb006f674301a0c45f34b3c08dee0fe49 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 29 Dec 2014 14:48:14 +0100 Subject: vga: implement horizontal pel panning in graphics modes This implements smooth scrolling, as used for example by Commander Keen and Second Reality. Unfortunately, this is not enough to avoid tearing in Commander Keen, because sometimes the wrong start address is used for a frame. On real EGA, the panning register is sampled on every line, while the display start is latched for the next frame at the start of the vertical retrace. On real VGA, the panning register is also latched, but at the end of the vertical retrace. It looks like Keen exploits this by only waiting for horizontal retrace when setting the display start, but implementing it breaks the 256-color Keen games... Signed-off-by: Paolo Bonzini --- hw/display/cirrus_vga.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'hw/display/cirrus_vga.c') diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c index e637e5a..150883a 100644 --- a/hw/display/cirrus_vga.c +++ b/hw/display/cirrus_vga.c @@ -43,6 +43,7 @@ #include "hw/qdev-properties.h" #include "migration/vmstate.h" #include "ui/pixel_ops.h" +#include "vga_regs.h" #include "cirrus_vga_internal.h" #include "qom/object.h" #include "ui/console.h" @@ -1121,6 +1122,9 @@ static void cirrus_get_params(VGACommonState *s1, params->line_compare = s->vga.cr[0x18] | ((s->vga.cr[0x07] & 0x10) << 4) | ((s->vga.cr[0x09] & 0x40) << 3); + + params->hpel = s->vga.ar[VGA_ATC_PEL]; + params->hpel_split = s->vga.ar[VGA_ATC_MODE] & 0x20; } static uint32_t cirrus_get_bpp16_depth(CirrusVGAState * s) -- cgit v1.1