diff options
Diffstat (limited to 'hw/vga.c')
| -rw-r--r-- | hw/vga.c | 36 |
1 files changed, 28 insertions, 8 deletions
@@ -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 +1903,10 @@ 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; |