strtoufix32.c

用于嵌入式Linux系统的标准C的库函数

#ifdef __SPE__ 

#include <_ansi.h>
#include <limits.h>
#include <errno.h>
#include <stdlib.h>
#include <reent.h>
#include "vfieeefp.h"

/*
 * Convert a string to a fixed-point 32-bit value.
 *
 * Ignores `locale' stuff.
 */
__uint32_t
_DEFUN (_strtoufix32_r, (rptr, nptr, endptr),
	struct _reent *rptr _AND
	_CONST char *nptr _AND
	char **endptr)
{
  union double_union dbl;
  int exp, negexp;
  __uint32_t tmp, tmp2, result = 0;

  dbl.d = _strtod_r (rptr, nptr, endptr);

  /* treat NAN as domain error, +/- infinity as saturation */
  if (!finite(dbl.d))
    {
      if (isnan (dbl.d))
	{
	  rptr->_errno = EDOM;
	  return 0;
	}
      rptr->_errno = ERANGE;
      if (word0(dbl) & Sign_bit)
	return 0;
      return ULONG_MAX;
    }

  /* check for normal saturation */
  if (dbl.d >= 1.0)
    {
      rptr->_errno = ERANGE;
      return ULONG_MAX;
    }
  else if (dbl.d < 0)
    {
      rptr->_errno = ERANGE;
      return 0;
    }

  /* otherwise we have normal positive number in range */

  /* strip off exponent */
  exp = ((word0(dbl) & Exp_mask) >> Exp_shift) - Bias;
  negexp = -exp;
  if (negexp > 32)
    return 0;
  word0(dbl) &= ~(Exp_mask | Sign_bit);
  /* add in implicit normalized bit */
  word0(dbl) |= Exp_msk1;
  /* shift so result is contained left-justified in word */
  tmp = word0(dbl) << Ebits;
  tmp |= ((unsigned long)word1(dbl) >> (32 - Ebits));
  /* perform rounding */
  if (negexp > 1)
    {
      tmp2 = tmp + (1 << (negexp - 2));
      result = (tmp2 >> (negexp - 1));
      /* if rounding causes carry, add carry bit in */
      if (tmp2 < tmp)
	result += 1 << (32 - negexp);
    }
  else
    {
      result = tmp + ((word1(dbl) & (1 << (32 - Ebits - 1))) != 0);
      /* if rounding causes carry, then saturation has occurred */
      if (result < tmp)
	{
	  rptr->_errno = ERANGE;
	  return ULONG_MAX;
	}
    }

  return result;
}

#ifndef _REENT_ONLY

__uint32_t
_DEFUN (strtoufix32, (s, ptr, base),
	_CONST char *s _AND
	char **ptr)
{
  return _strtoufix32_r (_REENT, s, ptr);
}

#endif

#endif /* __SPE__ */