diff libquadmath/printf/flt1282mpn.c @ 68:561a7518be6b

update gcc-4.6
author Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
date Sun, 21 Aug 2011 07:07:55 +0900
parents
children 1830386684a0
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libquadmath/printf/flt1282mpn.c	Sun Aug 21 07:07:55 2011 +0900
@@ -0,0 +1,136 @@
+/* Copyright (C) 1995,1996,1997,1998,1999,2002,2003
+	Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <float.h>
+#include <math.h>
+#include <stdlib.h>
+#include "gmp-impl.h"
+
+/* Convert a `__float128' in IEEE854 quad-precision format to a
+   multi-precision integer representing the significand scaled up by its
+   number of bits (113 for long double) and an integral power of two
+   (MPN frexpl). */
+
+mp_size_t
+mpn_extract_flt128 (mp_ptr res_ptr, mp_size_t size,
+		      int *expt, int *is_neg,
+		      __float128 value)
+{
+  ieee854_float128 u;
+  u.value = value;
+
+  *is_neg = u.ieee.negative;
+  *expt = (int) u.ieee.exponent - IEEE854_FLOAT128_BIAS;
+
+#if BITS_PER_MP_LIMB == 32
+  res_ptr[0] = u.ieee.mant_low; /* Low-order 32 bits of fraction.  */
+  res_ptr[1] = (u.ieee.mant_low >> 32);
+  res_ptr[2] = u.ieee.mant_high;
+  res_ptr[3] = (u.ieee.mant_high >> 32); /* High-order 32 bits.  */
+  #define N 4
+#elif BITS_PER_MP_LIMB == 64
+  res_ptr[0] = u.ieee.mant_low;
+  res_ptr[1] = u.ieee.mant_high;
+  #define N 2
+#else
+  #error "mp_limb size " BITS_PER_MP_LIMB "not accounted for"
+#endif
+/* The format does not fill the last limb.  There are some zeros.  */
+#define NUM_LEADING_ZEROS (BITS_PER_MP_LIMB \
+			   - (FLT128_MANT_DIG - ((N - 1) * BITS_PER_MP_LIMB)))
+
+  if (u.ieee.exponent == 0)
+    {
+      /* A biased exponent of zero is a special case.
+	 Either it is a zero or it is a denormal number.  */
+      if (res_ptr[0] == 0 && res_ptr[1] == 0
+	  && res_ptr[N - 2] == 0 && res_ptr[N - 1] == 0) /* Assumes N<=4.  */
+	/* It's zero.  */
+	*expt = 0;
+      else
+	{
+	  /* It is a denormal number, meaning it has no implicit leading
+  	     one bit, and its exponent is in fact the format minimum.  */
+	  int cnt;
+
+#if N == 2
+	  if (res_ptr[N - 1] != 0)
+	    {
+	      count_leading_zeros (cnt, res_ptr[N - 1]);
+	      cnt -= NUM_LEADING_ZEROS;
+	      res_ptr[N - 1] = res_ptr[N - 1] << cnt
+			       | (res_ptr[0] >> (BITS_PER_MP_LIMB - cnt));
+	      res_ptr[0] <<= cnt;
+	      *expt = FLT128_MIN_EXP - 1 - cnt;
+	    }
+	  else
+	    {
+	      count_leading_zeros (cnt, res_ptr[0]);
+	      if (cnt >= NUM_LEADING_ZEROS)
+		{
+		  res_ptr[N - 1] = res_ptr[0] << (cnt - NUM_LEADING_ZEROS);
+		  res_ptr[0] = 0;
+		}
+	      else
+		{
+		  res_ptr[N - 1] = res_ptr[0] >> (NUM_LEADING_ZEROS - cnt);
+		  res_ptr[0] <<= BITS_PER_MP_LIMB - (NUM_LEADING_ZEROS - cnt);
+		}
+	      *expt = FLT128_MIN_EXP - 1
+		- (BITS_PER_MP_LIMB - NUM_LEADING_ZEROS) - cnt;
+	    }
+#else
+	  int j, k, l;
+
+	  for (j = N - 1; j > 0; j--)
+	    if (res_ptr[j] != 0)
+	      break;
+
+	  count_leading_zeros (cnt, res_ptr[j]);
+	  cnt -= NUM_LEADING_ZEROS;
+	  l = N - 1 - j;
+	  if (cnt < 0)
+	    {
+	      cnt += BITS_PER_MP_LIMB;
+	      l--;
+	    }
+	  if (!cnt)
+	    for (k = N - 1; k >= l; k--)
+	      res_ptr[k] = res_ptr[k-l];
+	  else
+	    {
+	      for (k = N - 1; k > l; k--)
+		res_ptr[k] = res_ptr[k-l] << cnt
+			     | res_ptr[k-l-1] >> (BITS_PER_MP_LIMB - cnt);
+	      res_ptr[k--] = res_ptr[0] << cnt;
+	    }
+
+	  for (; k >= 0; k--)
+	    res_ptr[k] = 0;
+	  *expt = FLT128_MIN_EXP - 1 - l * BITS_PER_MP_LIMB - cnt;
+#endif
+	}
+    }
+  else
+    /* Add the implicit leading one bit for a normalized number.  */
+    res_ptr[N - 1] |= (mp_limb_t) 1 << (FLT128_MANT_DIG - 1
+					- ((N - 1) * BITS_PER_MP_LIMB));
+
+  return N;
+}