IMR_REG
#define irq_enabled(x) ( ( inb ( IMR_REG(x) ) & IMR_BIT(x) ) == 0 )
#define enable_irq(x) outb ( inb( IMR_REG(x) ) & ~IMR_BIT(x), IMR_REG(x) )
#define disable_irq(x) outb ( inb( IMR_REG(x) ) | IMR_BIT(x), IMR_REG(x) )