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kernel/linux-rt-4.4.41/arch/mips/math-emu/dp_fsp.c 1.71 KB
5113f6f70   김현기   kernel add
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  /* IEEE754 floating point arithmetic
   * double precision: common utilities
   */
  /*
   * MIPS floating point support
   * Copyright (C) 1994-2000 Algorithmics Ltd.
   *
   *  This program is free software; you can distribute it and/or modify it
   *  under the terms of the GNU General Public License (Version 2) as
   *  published by the Free Software Foundation.
   *
   *  This program is distributed in the hope it will be useful, but WITHOUT
   *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   *  for more details.
   *
   *  You should have received a copy of the GNU General Public License along
   *  with this program; if not, write to the Free Software Foundation, Inc.,
   *  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA.
   */
  
  #include "ieee754sp.h"
  #include "ieee754dp.h"
  
  static inline union ieee754dp ieee754dp_nan_fsp(int xs, u64 xm)
  {
  	return builddp(xs, DP_EMAX + 1 + DP_EBIAS,
  		       xm << (DP_FBITS - SP_FBITS));
  }
  
  union ieee754dp ieee754dp_fsp(union ieee754sp x)
  {
  	COMPXSP;
  
  	EXPLODEXSP;
  
  	ieee754_clearcx();
  
  	FLUSHXSP;
  
  	switch (xc) {
  	case IEEE754_CLASS_SNAN:
  		return ieee754dp_nanxcpt(ieee754dp_nan_fsp(xs, xm));
  
  	case IEEE754_CLASS_QNAN:
  		return ieee754dp_nan_fsp(xs, xm);
  
  	case IEEE754_CLASS_INF:
  		return ieee754dp_inf(xs);
  
  	case IEEE754_CLASS_ZERO:
  		return ieee754dp_zero(xs);
  
  	case IEEE754_CLASS_DNORM:
  		/* normalize */
  		while ((xm >> SP_FBITS) == 0) {
  			xm <<= 1;
  			xe--;
  		}
  		break;
  
  	case IEEE754_CLASS_NORM:
  		break;
  	}
  
  	/*
  	 * Can't possibly overflow,underflow, or need rounding
  	 */
  
  	/* drop the hidden bit */
  	xm &= ~SP_HIDDEN_BIT;
  
  	return builddp(xs, xe + DP_EBIAS,
  		       (u64) xm << (DP_FBITS - SP_FBITS));
  }