Function vga_SwitchMode

sys/msdos/vidvga.c:833–853

* Switches modes of the video card. * * If mode == MODETEXT (0x03), then the card is placed into text * mode. If mode == 640x480, then the card is placed into vga * mode (video mode 0x12). No other modes are currently supported. * */

 *
 */
static void
vga_SwitchMode(unsigned int mode)
{
    union REGS regs;

    if ((mode == MODE640x480) || (mode == MODETEXT)) {
        if (iflags.usevga && (mode == MODE640x480)) {
            iflags.grmode = 1;
        } else {
            iflags.grmode = 0;
        }
        regs.x.ax = mode;
        (void) int86(VIDEO_BIOS, &regs, &regs);
    } else {
        iflags.grmode = 0; /* force text mode for error msg */
        regs.x.ax = MODETEXT;
        (void) int86(VIDEO_BIOS, &regs, &regs);
        g_attribute = attrib_text_normal;
        impossible("vga_SwitchMode: Bad video mode requested 0x%X", mode);
    }
}

/*
 * This allows grouping of several tasks to be done when