diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/boot/video-vga.c | 22 |
1 files changed, 13 insertions, 9 deletions
diff --git a/arch/x86/boot/video-vga.c b/arch/x86/boot/video-vga.c index 5d4742e..95d86ce 100644 --- a/arch/x86/boot/video-vga.c +++ b/arch/x86/boot/video-vga.c @@ -129,41 +129,45 @@ u16 vga_crtc(void) return (inb(0x3cc) & 1) ? 0x3d4 : 0x3b4; } -static void vga_set_480_scanlines(int end) +static void vga_set_480_scanlines(int lines) { - u16 crtc; - u8 csel; + u16 crtc; /* CRTC base address */ + u8 csel; /* CRTC miscellaneous output register */ + u8 ovfw; /* CRTC overflow register */ + int end = lines-1; crtc = vga_crtc(); + ovfw = 0x3c | ((end >> (8-1)) & 0x02) | ((end >> (9-6)) & 0x40); + out_idx(0x0c, crtc, 0x11); /* Vertical sync end, unlock CR0-7 */ out_idx(0x0b, crtc, 0x06); /* Vertical total */ - out_idx(0x3e, crtc, 0x07); /* Vertical overflow */ + out_idx(ovfw, crtc, 0x07); /* Vertical overflow */ out_idx(0xea, crtc, 0x10); /* Vertical sync start */ - out_idx(end, crtc, 0x12); /* Vertical display end */ + out_idx(end, crtc, 0x12); /* Vertical display end */ out_idx(0xe7, crtc, 0x15); /* Vertical blank start */ out_idx(0x04, crtc, 0x16); /* Vertical blank end */ csel = inb(0x3cc); csel &= 0x0d; csel |= 0xe2; - outb(csel, 0x3cc); + outb(csel, 0x3c2); } static void vga_set_80x30(void) { - vga_set_480_scanlines(0xdf); + vga_set_480_scanlines(30*16); } static void vga_set_80x34(void) { vga_set_14font(); - vga_set_480_scanlines(0xdb); + vga_set_480_scanlines(34*14); } static void vga_set_80x60(void) { vga_set_8font(); - vga_set_480_scanlines(0xdf); + vga_set_480_scanlines(60*8); } static int vga_set_mode(struct mode_info *mode) |