Function vga_detect

sys/msdos/vidvga.c:927–948

* This will verify the existence of a VGA adapter on the machine. * Video function call 0x1a returns 0x1a in AL if successful, and * returns the following values in BL for the active display: * * 0=no display, 1=MDA, 2=CGA, 4=EGA(color-monitor), * 5=EGA(mono-monitor), 6=PGA, 7=VGA(mono-monitor), 8=VGA(color-monitor), * 0xB=MCGA(mono-monitor), 0xC=MCGA(color-monitor), 0xFF=unknown) */

 * 0xB=MCGA(mono-monitor), 0xC=MCGA(color-monitor), 0xFF=unknown)
 */
int
vga_detect(void)
{
    union REGS regs;

    regs.h.al = 0;
    regs.h.ah = 0x1a;
    (void) int86(VIDEO_BIOS, &regs, &regs);
    /*
     * debug
     *
     *  printf("vga_detect returned al=%02x, bh=%02x, bl=%02x\n",
     *         (int)regs.h.al, (int)regs.h.bh, (int)regs.h.bl);
     *  getch();
     */
    if ((int) regs.h.al == 0x1a) {
        if (((int) regs.h.bl == 8) || ((int) regs.h.bl == 7)) {
            return 1;
        }
    }
    return 0;
}

extern int curframecolor;    /* video.c */