1 files changed, 103 insertions, 0 deletions
diff --git a/sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c b/sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c
new file mode 100644
index 0000000000..8a2d45e2d8
--- /dev/null
+++ b/sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c
@@ -0,0 +1,103 @@
+/* Copyright (C) 1995, 1996, 1997, 1998, 1999, 2002, 2003, 2004, 2006
+	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 "gmp.h"
+#include "gmp-impl.h"
+#include <ieee754.h>
+#include <float.h>
+#include <math.h>
+
+/* Convert a multi-precision integer of the needed number of bits (106
+   for long double) and an integral power of two to a `long double' in
+   IBM extended format.  */
+
+long double
+__mpn_construct_long_double (mp_srcptr frac_ptr, int expt, int sign)
+{
+  union ibm_extended_long_double u;
+  unsigned long hidden2, lzcount;
+  unsigned long long hi, lo;
+
+  u.ieee.negative = sign;
+  u.ieee.negative2 = sign;
+  u.ieee.exponent = expt + IBM_EXTENDED_LONG_DOUBLE_BIAS;
+  u.ieee.exponent2 = expt - 53 + IBM_EXTENDED_LONG_DOUBLE_BIAS;
+
+#if BITS_PER_MP_LIMB == 32
+  /* The low order 53 bits (52 + hidden) go into the lower double */
+  lo = frac_ptr[0];
+  lo |= (frac_ptr[1] & ((1LL << (53 - 32)) - 1)) << 32;
+  hidden2 = (frac_ptr[1] >> (52 - 32)) & ((mp_limb_t) 1);
+  /* The high order 53 bits (52 + hidden) go into the upper double */
+  hi = (frac_ptr[1] >> (53 - 32)) & ((1 << 11) - 1);
+  hi |= ((unsigned long long) frac_ptr[2]) << 11;
+  hi |= ((unsigned long long) frac_ptr[3]) << (32 + 11);
+#elif BITS_PER_MP_LIMB == 64
+  /* The low order 53 bits (52 + hidden) go into the lower double */
+  lo = frac_ptr[0] & (((mp_limb_t) 1 << 53) - 1);
+  hidden2 = (frac_ptr[0] >> 52) & ((mp_limb_t) 1);
+  /* The high order 53 bits (52 + hidden) go into the upper double */
+  hi = (frac_ptr[0] >> 53) & (((mp_limb_t) 1 << 11) - 1);
+  hi |= (frac_ptr[1] << 11);
+#else
+  #error "mp_limb size " BITS_PER_MP_LIMB "not accounted for"
+#endif
+
+  if (lo != 0L)
+    {
+      /* hidden2 bit of low double controls rounding of the high double.
+	 If hidden2 is '1' then round up hi and adjust lo (2nd mantissa)
+	 plus change the sign of the low double to compensate.  */
+      if (hidden2)
+	{
+	  hi++;
+	  u.ieee.negative2 = !sign;
+	  lo = (1LL << 53) - lo;
+	}
+
+      /* The hidden bit of the lo mantissa is zero so we need to normalize
+	 it for the low double.  Shift it left until the hidden bit is '1'
+	 then adjust the 2nd exponent accordingly.  */
+
+      if (sizeof (lo) == sizeof (long))
+	lzcount = __builtin_clzl (lo);
+      else if ((lo >> 32) != 0)
+	lzcount = __builtin_clzl ((long) (lo >> 32));
+      else
+	lzcount = __builtin_clzl ((long) lo) + 32;
+      lzcount = lzcount - 11;
+      if (lzcount > 0)
+	{
+	  lo = lo << lzcount;
+	  u.ieee.exponent2 = u.ieee.exponent2 - lzcount;
+	}
+    }
+  else
+    {
+      u.ieee.negative2 = 0;
+      u.ieee.exponent2 = 0;
+    }
+
+  u.ieee.mantissa3 = lo & 0xffffffffLL;
+  u.ieee.mantissa2 = (lo >> 32) & 0xffffff;
+  u.ieee.mantissa1 = hi & 0xffffffffLL;
+  u.ieee.mantissa0 = (hi >> 32) & ((1LL << (LDBL_MANT_DIG - 86)) - 1);
+
+  return u.d;
+}