alt_io_redirect.c

nios中自定义指令集实现三角函数的软件部分。

/******************************************************************************
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* License Agreement                                                           *
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* Copyright (c) 2004 Altera Corporation, San Jose, California, USA.           *
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/******************************************************************************
*                                                                             *
* THIS IS A LIBRARY READ-ONLY SOURCE FILE. DO NOT EDIT IT DIRECTLY.           *
*                                                                             *
* Overriding HAL Functions                                                    *
*                                                                             *
* To provide your own implementation of a HAL function, include the file in   *
* your Nios II IDE application project. When building the executable, the     *
* Nios II IDE finds your function first, and uses it in place of the HAL      *
* version.                                                                    *
*                                                                             *
******************************************************************************/

#include <stddef.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>

#include "sys/alt_dev.h"
#include "priv/alt_file.h"


/*
 * alt_open_fd() is similar to open() in that it is used to obtain a file
 * descriptor for the file named "name". The "flags" and "mode" arguments are
 * identical to the "flags" and "mode" arguments of open().
 *
 * The distinction between the two functions is that the file descriptor 
 * structure to use is passed in as an argument, rather than allocated from the
 * list of free file descriptors.
 *
 * This is used by alt_io_redirect() to redirect the stdin, stdout and stderr
 * file descriptors to point to new devices.
 *
 * If the device can not be succesfully opened, then the input file descriptor
 * remains unchanged.
 */

static void alt_open_fd(alt_fd* fd, const char* name, int flags, int mode)
{
  int old;

  old = open (name, flags, mode);

  if (old >= 0)
  {
    fd->dev      = alt_fd_list[old].dev;
    fd->priv     = alt_fd_list[old].priv;
    fd->fd_flags = alt_fd_list[old].fd_flags;

    alt_release_fd (old);
  }
} 

/*
 * alt_io_redirect() is called once the device/filesystem lists have been 
 * initialised, but before main(). Its function is to redirect standard in,
 * standard out and standard error so that they point to the devices selected by
 * the user (as defined in system.h).
 *
 * Prior to the call to this function, io is directed towards /dev/null. If
 * i/o can not be redirected to the requested device, for example if the device 
 * does not exist, then it remains directed at /dev/null. 
 */
 
void alt_io_redirect(const char* stdout_dev, 
                     const char* stdin_dev, 
                     const char* stderr_dev)
{
  /* Redirect the channels */

  alt_open_fd (&alt_fd_list[STDOUT_FILENO], stdout_dev, O_WRONLY, 0777);
  alt_open_fd (&alt_fd_list[STDIN_FILENO], stdin_dev, O_RDONLY, 0777);
  alt_open_fd (&alt_fd_list[STDERR_FILENO], stderr_dev, O_WRONLY, 0777);
}