Function vesa_SwitchMode

sys/msdos/vidvesa.c:1259–1290

* Switches modes of the video card. * * If mode == MODETEXT (0x03), then the card is placed into text * mode. Otherwise, the card is placed in the mode selected by * vesa_detect. * */

 *
 */
static void
vesa_SwitchMode(unsigned mode)
{
    __dpmi_regs regs;

    if (mode == MODETEXT) {
        iflags.grmode = 0;
        memset(&regs, 0, sizeof(regs));
        regs.x.ax = mode;
        (void) __dpmi_int(VIDEO_BIOS, &regs);
#ifdef SIMULATE_CURSOR
        free(undercursor);
        undercursor = NULL;
#endif
    } else if (mode >= 0x100) {
        iflags.grmode = 1;
        memset(&regs, 0, sizeof(regs));
        regs.x.ax = 0x4F02;
        regs.x.bx = mode;
        (void) __dpmi_int(VIDEO_BIOS, &regs);
        /* Record that the window position is unknown */
        vesa_win_pos[0] = 0xFFFFFFFF;
        vesa_win_pos[1] = 0xFFFFFFFF;
    } else {
        iflags.grmode = 0; /* force text mode for error msg */
        memset(&regs, 0, sizeof(regs));
        regs.x.ax = MODETEXT;
        (void) __dpmi_int(VIDEO_BIOS, &regs);
        g_attribute = attrib_text_normal;
        impossible("vesa_SwitchMode: Bad video mode requested 0x%X", mode);
    }
}

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