io.h

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#ifndef _IO_H
#define _IO_H

/*
  Procedure..: outb
  Description..: Write a byte of data to a port.
*/
#define outb(port, data)                    \
  asm volatile ("outb %%al,%%dx" : : "a" (data), "d" (port))

/*
  Procedure..: inb
  Description..: Read a byte of data from a port.
*/
#define inb(port) ({                        \
      unsigned char r;                      \
      asm volatile ("inb %%dx,%%al": "=a" (r): "d" (port)); \
      r;                            \
    })

#endif