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[Qemu-devel] [PATCH 3/3] vga: fix CGA 640x200 mode
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 3/3] vga: fix CGA 640x200 mode |
Date: |
Sat, 8 Aug 2015 15:11:09 +0200 |
SeaBIOS programs the CGA 2-color 640x200 mode with 0xC1 in the maximum
scan line register. Ordinarily, this would mean 100 vertical lines,
but the CGA modes ignore bits 4:0 (DOSBox's BIOS also uses 0xC1).
Unfortunately, the test used to catch CGA modes worked for 4-color
320x200 graphics, but not for the 2-color 640x200 mode.
Signed-off-by: Paolo Bonzini <address@hidden>
---
hw/display/vga.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/hw/display/vga.c b/hw/display/vga.c
index 19dcb6b..7d4e1b0 100644
--- a/hw/display/vga.c
+++ b/hw/display/vga.c
@@ -1442,12 +1442,11 @@ static void vga_draw_graphic(VGACommonState *s, int
full_update)
shift_control = (s->gr[VGA_GFX_MODE] >> 5) & 3;
double_scan = (s->cr[VGA_CRTC_MAX_SCAN] >> 7);
- if (shift_control != 1) {
+ if (s->cr[VGA_CRTC_MODE] & 1) {
multi_scan = (((s->cr[VGA_CRTC_MAX_SCAN] & 0x1f) + 1) << double_scan)
- 1;
} else {
/* in CGA modes, multi_scan is ignored */
- /* XXX: is it correct ? */
multi_scan = double_scan;
}
multi_run = multi_scan;
--
2.4.3