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[Qemu-devel] [PATCH v5 4/6] vga: add some optional CGA compatibility hac
From: |
Matthew Ogilvie |
Subject: |
[Qemu-devel] [PATCH v5 4/6] vga: add some optional CGA compatibility hacks |
Date: |
Sun, 9 Sep 2012 19:27:44 -0600 |
This patch adds some optional compatibility hacks (default
disabled) to allow Microport UNIX to function under qemu.
I've tried to structure it to be easy to add more hacks for other
old CGA programs, if anyone ever needs them.
Microport UNIX System V/386 v 2.1 (ca 1987) tries to program
the CGA registers directly with neither the assistance of BIOS, nor
with proper handling of EGA/VGA-only registers. Note that it didn't
work on real VGA hardware, either (although in that case, the most
obvious problems seemed to be out-of-range hsync and/or vsync
signalling, rather than the issues in this patch).
Eventually real MDA and/or CGA support might provide an alternative to
this patch, although a hybrid approach like this patch might still
be useful in marginal cases.
Signed-off-by: Matthew Ogilvie <address@hidden>
---
hw/pc.h | 4 ++++
hw/vga.c | 37 +++++++++++++++++++++++++++++--------
qemu-options.hx | 19 +++++++++++++++++++
vl.c | 23 +++++++++++++++++++++++
4 files changed, 75 insertions(+), 8 deletions(-)
diff --git a/hw/pc.h b/hw/pc.h
index e4db071..37e2f87 100644
--- a/hw/pc.h
+++ b/hw/pc.h
@@ -176,6 +176,10 @@ enum vga_retrace_method {
extern enum vga_retrace_method vga_retrace_method;
+#define VGA_CGA_HACK_PALETTE_BLANKING (1<<0)
+#define VGA_CGA_HACK_FONT_HEIGHT (1<<1)
+extern int vga_cga_hacks;
+
static inline DeviceState *isa_vga_init(ISABus *bus)
{
ISADevice *dev;
diff --git a/hw/vga.c b/hw/vga.c
index f82ced8..fb08dc0 100644
--- a/hw/vga.c
+++ b/hw/vga.c
@@ -547,14 +547,31 @@ void vga_ioport_write(void *opaque, uint32_t addr,
uint32_t val)
printf("vga: write CR%x = 0x%02x\n", s->cr_index, val);
#endif
/* handle CR0-7 protection */
- if ((s->cr[VGA_CRTC_V_SYNC_END] & VGA_CR11_LOCK_CR0_CR7) &&
- s->cr_index <= VGA_CRTC_OVERFLOW) {
- /* can always write bit 4 of CR7 */
- if (s->cr_index == VGA_CRTC_OVERFLOW) {
- s->cr[VGA_CRTC_OVERFLOW] = (s->cr[VGA_CRTC_OVERFLOW] & ~0x10) |
- (val & 0x10);
+ if (s->cr[VGA_CRTC_V_SYNC_END] & VGA_CR11_LOCK_CR0_CR7) {
+ if (s->cr_index <= VGA_CRTC_OVERFLOW) {
+ /* can always write bit 4 of CR7 */
+ if (s->cr_index == VGA_CRTC_OVERFLOW) {
+ s->cr[VGA_CRTC_OVERFLOW] =
+ (s->cr[VGA_CRTC_OVERFLOW] & ~0x10) | (val & 0x10);
+ }
+ return;
+ } else if ((vga_cga_hacks & VGA_CGA_HACK_FONT_HEIGHT) &&
+ !(s->sr[VGA_SEQ_CLOCK_MODE] & VGA_SR01_CHAR_CLK_8DOTS))
{
+ /* extra CGA compatibility hacks (not in standard VGA) */
+ if (s->cr_index == VGA_CRTC_MAX_SCAN &&
+ val == 7 &&
+ (s->cr[VGA_CRTC_MAX_SCAN] & 0xf) == 0xf) {
+ return;
+ } else if (s->cr_index == VGA_CRTC_CURSOR_START &&
+ val == 6 &&
+ (s->cr[VGA_CRTC_MAX_SCAN] & 0xf) == 0xf) {
+ val = 0xd;
+ } else if (s->cr_index == VGA_CRTC_CURSOR_END &&
+ val == 7 &&
+ (s->cr[VGA_CRTC_MAX_SCAN] & 0xf) == 0xf) {
+ val = 0xe;
+ }
}
- return;
}
s->cr[s->cr_index] = val;
@@ -1886,7 +1903,11 @@ static void vga_update_display(void *opaque)
/* nothing to do */
} else {
full_update = 0;
- if (!(s->ar_index & 0x20)) {
+ if (!(s->ar_index & 0x20) &&
+ /* extra CGA compatibility hacks (not in standard VGA) */
+ (!(vga_cga_hacks & VGA_CGA_HACK_PALETTE_BLANKING) ||
+ s->ar_index != 0 ||
+ !s->ar_flip_flop)) {
graphic_mode = GMODE_BLANK;
} else {
graphic_mode = s->gr[VGA_GFX_MISC] & VGA_GR06_GRAPHICS_MODE;
diff --git a/qemu-options.hx b/qemu-options.hx
index 3e8085d..68925f3 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -975,6 +975,25 @@ Valid optional properties are
@item retrace=dumb|precise
Select dumb (default) or precise VGA retrace logic, useful for some
DOS games/demos.
address@hidden address@hidden@var{hack2}[+...]]
+Enable various extra CGA compatibility hacks for programs that are
+trying to directly set CGA modes without BIOS assistance nor
+real knowledge of EGA/VGA. These might only work with -vga std.
+Valid hacks are
address@hidden @option
address@hidden palette_blanking
+Wait to blank the screen until palette registers seem to actually be
+modified, instead of blanking it as soon as the palette address bit (0x10)
+of the attribute address register (0x3c0) is cleared.
address@hidden font_height
+Ignore attempts to change the VGA font height (index 9),
+cursor start (index 10), and cursor end (index 11) of the CRTC control
+registers (0x3d5) if trying to set them to the default for CGA fonts
+instead of VGA fonts.
address@hidden all
+Enable all CGA hacks. More CGA hacks may be added in future versions
+of qemu.
address@hidden table
@end table
ETEXI
diff --git a/vl.c b/vl.c
index febfd62..16d04a2 100644
--- a/vl.c
+++ b/vl.c
@@ -179,6 +179,7 @@ int main(int argc, char **argv)
static const char *data_dir;
const char *bios_name = NULL;
enum vga_retrace_method vga_retrace_method = VGA_RETRACE_DUMB;
+int vga_cga_hacks = 0;
DisplayType display_type = DT_DEFAULT;
int display_remote = 0;
const char* keyboard_layout = NULL;
@@ -1748,6 +1749,28 @@ static void select_vgahw (const char *p)
else if (strstart(opts, "precise", &nextopt))
vga_retrace_method = VGA_RETRACE_PRECISE;
else goto invalid_vga;
+ } else if (strstart(opts, ",cga_hacks=", &nextopt)) {
+ opts = nextopt;
+ while (*opts) {
+ if (strstart(opts, "all", &nextopt)) {
+ opts = nextopt;
+ vga_cga_hacks |= ~0;
+ } else if (strstart(opts, "palette_blanking", &nextopt)) {
+ opts = nextopt;
+ vga_cga_hacks |= VGA_CGA_HACK_PALETTE_BLANKING;
+ } else if (strstart(opts, "font_height", &nextopt)) {
+ opts = nextopt;
+ vga_cga_hacks |= VGA_CGA_HACK_FONT_HEIGHT;
+ } else {
+ break;
+ }
+
+ if (*opts == '+') {
+ opts++;
+ } else {
+ break;
+ }
+ }
} else goto invalid_vga;
opts = nextopt;
}
--
1.7.10.2.484.gcd07cc5
- [Qemu-devel] [PATCH v5 0/6] Running Microport UNIX (ca 1987), Matthew Ogilvie, 2012/09/09
- [Qemu-devel] [PATCH v5 1/6] fix some debug printf format strings, Matthew Ogilvie, 2012/09/09
- [Qemu-devel] [PATCH v5 3/6] qemu-options.hx: mention retrace= VGA option, Matthew Ogilvie, 2012/09/09
- [Qemu-devel] [PATCH v5 2/6] vl: fix -hdachs/-hda argument order parsing issues, Matthew Ogilvie, 2012/09/09
- [Qemu-devel] [PATCH v5 4/6] vga: add some optional CGA compatibility hacks,
Matthew Ogilvie <=
- [Qemu-devel] [PATCH v5 6/6] i8259: refactor pic_set_irq level logic, Matthew Ogilvie, 2012/09/09
- [Qemu-devel] [PATCH v5 5/6] i8259: fix so that dropping IRQ level always clears the interrupt request, Matthew Ogilvie, 2012/09/09
- Re: [Qemu-devel] [PATCH v5 5/6] i8259: fix so that dropping IRQ level always clears the interrupt request, Avi Kivity, 2012/09/10
- Re: [Qemu-devel] [PATCH v5 5/6] i8259: fix so that dropping IRQ level always clears the interrupt request, Jan Kiszka, 2012/09/10
- Re: [Qemu-devel] [PATCH v5 5/6] i8259: fix so that dropping IRQ level always clears the interrupt request, Avi Kivity, 2012/09/10
- Re: [Qemu-devel] [PATCH v5 5/6] i8259: fix so that dropping IRQ level always clears the interrupt request, Jan Kiszka, 2012/09/10
- Re: [Qemu-devel] [PATCH v5 5/6] i8259: fix so that dropping IRQ level always clears the interrupt request, Maciej W. Rozycki, 2012/09/10
- Re: [Qemu-devel] [PATCH v5 5/6] i8259: fix so that dropping IRQ level always clears the interrupt request, Avi Kivity, 2012/09/11
- Re: [Qemu-devel] [PATCH v5 5/6] i8259: fix so that dropping IRQ level always clears the interrupt request, Matthew Ogilvie, 2012/09/11
- Re: [Qemu-devel] [PATCH v5 5/6] i8259: fix so that dropping IRQ level always clears the interrupt request, Jan Kiszka, 2012/09/11