reg_convert.c

内核linux2.4.20,可跟rtlinux3.2打补丁 组成实时linux系统,编译内核

/*---------------------------------------------------------------------------+
 |  reg_convert.c                                                            |
 |                                                                           |
 |  Convert register representation.                                         |
 |                                                                           |
 | Copyright (C) 1992,1993,1994,1996,1997                                    |
 |                  W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
 |                  E-mail   [e-mail]                              |
 |                                                                           |
 |                                                                           |
 +---------------------------------------------------------------------------*/

#include "exception.h"
#include "fpu_emu.h"


int FPU_to_exp16(FPU_REG const *a, FPU_REG *x)
{
  int sign = getsign(a);

  *(long long *)&(x->sigl) = *(const long long *)&(a->sigl);

  /* Set up the exponent as a 16 bit quantity. */
  setexponent16(x, exponent(a));

  if ( exponent16(x) == EXP_UNDER )
    {
      /* The number is a de-normal or pseudodenormal. */
      /* We only deal with the significand and exponent. */

      if (x->sigh & 0x80000000)
	{
	  /* Is a pseudodenormal. */
	  /* This is non-80486 behaviour because the number
	     loses its 'denormal' identity. */
	  addexponent(x, 1);
	}
      else
	{
	  /* Is a denormal. */
	  addexponent(x, 1);
	  FPU_normalize_nuo(x);
	}
    }

  if ( !(x->sigh & 0x80000000) )
    {
      EXCEPTION(EX_INTERNAL | 0x180);
    }

  return sign;
}