关于C语言里的io.h里面的函数？

[Crazy_hand]

1.为什么每个函数都有两个差不多的，，例如： _open() 和 open()

2.这个定义的宏是干什么用的。。。

[fallening]

lz说哪个宏？

/* Copyright (C) 1996, 2000 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#ifndef	_SYS_IO_H
#define	_SYS_IO_H	1

#include <features.h>

__BEGIN_DECLS

/* If TURN_ON is TRUE, request for permission to do direct i/o on the
   port numbers in the range [FROM,FROM+NUM-1].  Otherwise, turn I/O
   permission off for that range.  This call requires root privileges.

   Portability note: not all Linux platforms support this call.  Most
   platforms based on the PC I/O architecture probably will, however.
   E.g., Linux/Alpha for Alpha PCs supports this.  */
extern int ioperm (unsigned long int __from, unsigned long int __num,
                   int __turn_on) __THROW;

/* Set the I/O privilege level to LEVEL.  If LEVEL>3, permission to
   access any I/O port is granted.  This call requires root
   privileges. */
extern int iopl (int __level) __THROW;

#if defined __GNUC__ && __GNUC__ >= 2

static __inline unsigned char
inb (unsigned short int port)
{
  unsigned char _v;

  __asm__ __volatile__ ("inb %w1,%0":"=a" (_v):"Nd" (port));
  return _v;
}

static __inline unsigned char
inb_p (unsigned short int port)
{
  unsigned char _v;

  __asm__ __volatile__ ("inb %w1,%0\noutb %%al,$0x80":"=a" (_v):"Nd" (port));
  return _v;
}

static __inline unsigned short int
inw (unsigned short int port)
{
  unsigned short _v;

  __asm__ __volatile__ ("inw %w1,%0":"=a" (_v):"Nd" (port));
  return _v;
}

static __inline unsigned short int
inw_p (unsigned short int port)
{
  unsigned short int _v;

  __asm__ __volatile__ ("inw %w1,%0\noutb %%al,$0x80":"=a" (_v):"Nd" (port));
  return _v;
}

static __inline unsigned int
inl (unsigned short int port)
{
  unsigned int _v;

  __asm__ __volatile__ ("inl %w1,%0":"=a" (_v):"Nd" (port));
  return _v;
}

static __inline unsigned int
inl_p (unsigned short int port)
{
  unsigned int _v;
  __asm__ __volatile__ ("inl %w1,%0\noutb %%al,$0x80":"=a" (_v):"Nd" (port));
  return _v;
}

static __inline void
outb (unsigned char value, unsigned short int port)
{
  __asm__ __volatile__ ("outb %b0,%w1": :"a" (value), "Nd" (port));
}

static __inline void
outb_p (unsigned char value, unsigned short int port)
{
  __asm__ __volatile__ ("outb %b0,%w1\noutb %%al,$0x80": :"a" (value),
			"Nd" (port));
}

static __inline void
outw (unsigned short int value, unsigned short int port)
{
  __asm__ __volatile__ ("outw %w0,%w1": :"a" (value), "Nd" (port));

}

static __inline void
outw_p (unsigned short int value, unsigned short int port)
{
  __asm__ __volatile__ ("outw %w0,%w1\noutb %%al,$0x80": :"a" (value),
			"Nd" (port));
}

static __inline void
outl (unsigned int value, unsigned short int port)
{
  __asm__ __volatile__ ("outl %0,%w1": :"a" (value), "Nd" (port));
}

static __inline void
outl_p (unsigned int value, unsigned short int port)
{
  __asm__ __volatile__ ("outl %0,%w1\noutb %%al,$0x80": :"a" (value),
			"Nd" (port));
}

static __inline void
insb (unsigned short int port, void *addr, unsigned long int count)
{
  __asm__ __volatile__ ("cld ; rep ; insb":"=D" (addr),
			"=c" (count):"d" (port), "0" (addr), "1" (count));
}

static __inline void
insw (unsigned short int port, void *addr, unsigned long int count)
{
  __asm__ __volatile__ ("cld ; rep ; insw":"=D" (addr),
			"=c" (count):"d" (port), "0" (addr), "1" (count));
}

static __inline void
insl (unsigned short int port, void *addr, unsigned long int count)
{
  __asm__ __volatile__ ("cld ; rep ; insl":"=D" (addr),
			"=c" (count):"d" (port), "0" (addr), "1" (count));
}

static __inline void
outsb (unsigned short int port, const void *addr, unsigned long int count)
{
  __asm__ __volatile__ ("cld ; rep ; outsb":"=S" (addr),
			"=c" (count):"d" (port), "0" (addr), "1" (count));
}

static __inline void
outsw (unsigned short int port, const void *addr, unsigned long int count)
{
  __asm__ __volatile__ ("cld ; rep ; outsw":"=S" (addr),
			"=c" (count):"d" (port), "0" (addr), "1" (count));
}

static __inline void
outsl (unsigned short int port, const void *addr, unsigned long int count)
{
  __asm__ __volatile__ ("cld ; rep ; outsl":"=S" (addr),
			"=c" (count):"d" (port), "0" (addr), "1" (count));
}

#endif	/* GNU C */

__END_DECLS
#endif /* _SYS_IO_H */

[Crazy_hand]

我说的是dir.h 里面的那个io.h里面的函数为什么都有两个 例_open()和 open()函数



2.这个定义的宏（_UWIN）是干什么用的。。。

[K行天下]

区别：
带有'_'前缀的函数是Mircrosoft的私有函数，基本上都是最贴近于Windows API的底层函数。

那个宏应该是定义在windows环境的情况吧

[Crazy_hand]

think you!!!