os print string reoutine

#define ROMAREA                 0x000A0000
#define VGA_FRAMEBUFFER         (ROMAREA + 0x00000000)
#define VGA_TEXTMONOCHROME      (ROMAREA + 0x00010000)
#define VGA_TEXTCOLOR           (ROMAREA + 0x00018000)

KFUNC void kvideo_putchr(uint16 x, uint16 y, char c, uint8 col)
{
    if (c == '\n' || c == '\r' || c == '\0') return;

    uint16 *vptr = (uint16*)VGA_TEXTCOLOR;
    *(vptr + x + (y * 80)) = (col << 8) | c;
}