alt_gettod.c

nios中自定义指令集实现三角函数的软件部分。

/******************************************************************************
*                                                                             *
* License Agreement                                                           *
*                                                                             *
* Copyright (c) 2004 Altera Corporation, San Jose, California, USA.           *
* All rights reserved.                                                        *
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* copy of this software and associated documentation files (the "Software"),  *
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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 <sys/time.h>
#include <sys/times.h>
#include <errno.h>

#include "sys/alt_alarm.h"
#include "alt_types.h"
#include "os/alt_syscall.h"

/*
 * Macro defining the number of micoseconds in a second.
 */

#define ALT_US (1000000)

/*
 * "alt_timezone" and "alt_resettime" are the values of the the reset time and
 * time zone set through the last call to settimeofday(). By default they are
 * zero initialised.
 */

struct timezone alt_timezone = {0, 0};
struct timeval  alt_resettime = {0, 0};

/*
 * gettimeofday() can be called to obtain a time structure which indicates the
 * current "wall clock" time. This is calculated using the elapsed number of
 * system clock ticks, and the value of "alt_resettime" and "alt_timezone" set
 * through the last call to settimeofday().  
 *
 * Warning: if this function is called concurrently with a call to 
 * settimeofday(), the value returned by gettimeofday() will be unreliable. 
 *
 * ALT_GETTIMEOFDAY is mapped onto the gettimeofday() system call in 
 * alt_syscall.h
 */
 
int ALT_GETTIMEOFDAY (struct timeval  *ptimeval, struct timezone *ptimezone)
{
  alt_u32 nticks = alt_nticks (); 
  alt_u32 tick_rate = alt_ticks_per_second ();

  /* 
   * Check to see if the system clock is running. This is indicated by a 
   * non-zero system clock rate. If the system clock is not running, an error
   * is generated and the contents of "ptimeval" and "ptimezone" are not
   * updated.
   */

  if (tick_rate)
  {
    ptimeval->tv_sec  = alt_resettime.tv_sec  + nticks/tick_rate;
    ptimeval->tv_usec = alt_resettime.tv_usec + 
      ((nticks*(ALT_US/tick_rate))%ALT_US);
 
    if (ptimezone)
    { 
      ptimezone->tz_minuteswest = alt_timezone.tz_minuteswest;
      ptimezone->tz_dsttime     = alt_timezone.tz_dsttime;
    }

    return 0;
  }

  return -ENOTSUP;
}