From c5a361c09a19e3b1a83557b01f11f04b27181a11 Mon Sep 17 00:00:00 2001 From: Kevin O'Connor Date: Tue, 2 Apr 2024 13:07:58 -0400 Subject: stdvga: Add stdvga_set_vertical_size() helper function Add helper function and update the bochsvga.c code to use it. This emphasizes the relationship between stdvga_get_vertical_size() and stdvga_set_vertical_size() code. Signed-off-by: Kevin O'Connor --- vgasrc/stdvga.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'vgasrc/stdvga.c') diff --git a/vgasrc/stdvga.c b/vgasrc/stdvga.c index 4bfa101a..afe26dbd 100644 --- a/vgasrc/stdvga.c +++ b/vgasrc/stdvga.c @@ -286,6 +286,17 @@ stdvga_get_vertical_size(void) return vde + 1; } +// Set vertical screen size (number of horizontal lines in the display) +void +stdvga_set_vertical_size(int lines) +{ + u16 crtc_addr = stdvga_get_crtc(); + u16 vde = lines - 1; + stdvga_crtc_write(crtc_addr, 0x12, vde); + u8 ovl = ((vde >> 7) & 0x02) + ((vde >> 3) & 0x40); + stdvga_crtc_mask(crtc_addr, 0x07, 0x42, ovl); +} + // Get offset into framebuffer accessible from real-mode 64K segment int stdvga_get_window(struct vgamode_s *curmode_g, int window) -- cgit