io.h

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#ifndef _ASM_IO_H
#define _ASM_IO_H

/**
*

 * This file contains the definitions for the x86 IO instructions
 * inb/inw/inl/outb/outw/outl and the "string versions" of the same
 * (insb/insw/insl/outsb/outsw/outsl). You can also use "pausing"
 * versions of the single-IO instructions (inb_p/inw_p/..).
 *
 * This file is not meant to be obfuscating: it's just complicated
 * to (a) handle it all in a way that makes gcc able to optimize it
 * as well as possible and (b) trying to avoid writing the same thing
 * over and over again with slight variations and possibly making a
 * mistake somewhere.


*/

/**
*

 * Thanks to James van Artsdalen for a better timing-fix than
 * the two short jumps: using outb's to a nonexistent port seems
 * to guarantee better timings even on fast machines.
 *
 * On the other hand, I'd like to be sure of a non-existent port:
 * I feel a bit unsafe about using 0x80 (should be safe, though)
 *
 *              Linus


*/

#ifdef SLOW_IO_BY_JUMPING
#define __SLOW_DOWN_IO __asm__ __volatile__("jmp 1f\n1:\tjmp 1f\n1:")
#else
#define __SLOW_DOWN_IO __asm__ __volatile__("outb %al,$0x80")
#endif

#ifdef REALLY_SLOW_IO
#define SLOW_DOWN_IO { __SLOW_DOWN_IO; __SLOW_DOWN_IO; __SLOW_DOWN_IO; __SLOW_DOWN_IO; }
#else
#define SLOW_DOWN_IO __SLOW_DOWN_IO
#endif

/**
*

 * Talk about misusing macros..


*/

#define __OUT1(s,x) \
extern inline void __out##s(unsigned x value, unsigned short port) {

#define __OUT2(s,s1,s2) \
__asm__ __volatile__ ("out" #s " %" s1 "0,%" s2 "1"

#define __OUT(s,s1,x) \
__OUT1(s,x) __OUT2(s,s1,"w") : : "a" (value), "d" (port)); } \
__OUT1(s##c,x) __OUT2(s,s1,"") : : "a" (value), "i" (port)); } \
__OUT1(s##_p,x) __OUT2(s,s1,"w") : : "a" (value), "d" (port)); SLOW_DOWN_IO; } \
__OUT1(s##c_p,x) __OUT2(s,s1,"") : : "a" (value), "i" (port)); SLOW_DOWN_IO; }

#define __IN1(s) \
extern inline unsigned int __in##s(unsigned short port) { unsigned int _v;

#define __IN2(s,s1,s2) \
__asm__ __volatile__ ("in" #s " %" s2 "1,%" s1 "0"

#define __IN(s,s1,i...) \
__IN1(s) __IN2(s,s1,"w") : "=a" (_v) : "d" (port) ,##i ); return _v; } \
__IN1(s##c) __IN2(s,s1,"") : "=a" (_v) : "i" (port) ,##i ); return _v; } \
__IN1(s##_p) __IN2(s,s1,"w") : "=a" (_v) : "d" (port) ,##i ); SLOW_DOWN_IO; return _v; } \
__IN1(s##c_p) __IN2(s,s1,"") : "=a" (_v) : "i" (port) ,##i ); SLOW_DOWN_IO; return _v; }

#define __INS(s) \
extern inline void ins##s(unsigned short port, void * addr, unsigned long count) \
{ __asm__ __volatile__ ("cld ; rep ; ins" #s \
: "=D" (addr), "=c" (count) : "d" (port),"0" (addr),"1" (count)); }

#define __OUTS(s) \
extern inline void outs##s(unsigned short port, const void * addr, unsigned long count) \
{ __asm__ __volatile__ ("cld ; rep ; outs" #s \
: "=S" (addr), "=c" (count) : "d" (port),"0" (addr),"1" (count)); }

__IN(b,"b","0" (0))
__IN(w,"w","0" (0))
__IN(l,"")

__OUT(b,"b",char)
__OUT(w,"w",short)
__OUT(l,,int)

__INS(b)
__INS(w)
__INS(l)

__OUTS(b)
__OUTS(w)
__OUTS(l)

/**
*

 * Note that due to the way __builtin_constant_p() works, you
 *  - can't use it inside a inline function (it will never be true)
 *  - you don't have to worry about side effects within the __builtin..


*/
#define outb(val,port) \
((__builtin_constant_p((port)) && (port) < 256) ? \
        __outbc((val),(port)) : \
        __outb((val),(port)))

#define inb(port) \
((__builtin_constant_p((port)) && (port) < 256) ? \
        __inbc(port) : \
        __inb(port))

#define outb_p(val,port) \
((__builtin_constant_p((port)) && (port) < 256) ? \
        __outbc_p((val),(port)) : \
        __outb_p((val),(port)))

#define inb_p(port) \
((__builtin_constant_p((port)) && (port) < 256) ? \
        __inbc_p(port) : \
        __inb_p(port))

#define outw(val,port) \
((__builtin_constant_p((port)) && (port) < 256) ? \
        __outwc((val),(port)) : \
        __outw((val),(port)))

#define inw(port) \
((__builtin_constant_p((port)) && (port) < 256) ? \
        __inwc(port) : \
        __inw(port))

#define outw_p(val,port) \
((__builtin_constant_p((port)) && (port) < 256) ? \
        __outwc_p((val),(port)) : \
        __outw_p((val),(port)))

#define inw_p(port) \
((__builtin_constant_p((port)) && (port) < 256) ? \
        __inwc_p(port) : \
        __inw_p(port))

#define outl(val,port) \
((__builtin_constant_p((port)) && (port) < 256) ? \
        __outlc((val),(port)) : \
        __outl((val),(port)))

#define inl(port) \
((__builtin_constant_p((port)) && (port) < 256) ? \
        __inlc(port) : \
        __inl(port))

#define outl_p(val,port) \
((__builtin_constant_p((port)) && (port) < 256) ? \
        __outlc_p((val),(port)) : \
        __outl_p((val),(port)))

#define inl_p(port) \
((__builtin_constant_p((port)) && (port) < 256) ? \
        __inlc_p(port) : \
        __inl_p(port))

#endif

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