added mpfr_set_ld and test file

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@2039 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 123 insertions, 0 deletions

diff --git a/set_ld.c b/set_ld.c
new file mode 100644
index 000000000..ade704731
--- /dev/null
+++ b/set_ld.c
@@ -0,0 +1,123 @@
+/* mpfr_set_ld -- convert a machine long double to
+                  a multiple precision floating-point number
+
+Copyright 2002 Free Software Foundation, Inc.
+
+This file is part of the MPFR Library.
+
+The MPFR 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 MPFR 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 MPFR Library; see the file COPYING.LIB.  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 "mpfr.h"
+#include "mpfr-impl.h"
+
+#ifndef LDBL_MANT_DIG
+#define LDBL_MANT_DIG 113 /* works also if long double == quad */
+#endif
+
+#ifndef DBL_MANT_DIG
+#define DBL_MANT_DIG 53
+#endif
+
+int
+mpfr_set_ld (mpfr_ptr r, long double d, mp_rnd_t rnd_mode)
+{
+  mpfr_t t, u;
+  int inexact, shift_exp = 0, inexact2 = 0;
+
+  mpfr_init2 (t, LDBL_MANT_DIG);
+  mpfr_init2 (u, DBL_MANT_DIG);
+  mpfr_set_ui (t, 0, GMP_RNDN);
+  while (d != 0.0)
+    {
+      mpfr_set_d (u, (double) d, GMP_RNDN);
+      if (mpfr_inf_p (u) && (d + d != d))
+        { /* d is neither +Inf nor -Inf and u is Inf: this implies that an
+             overflow occured, i.e. the exponent of d is too large for the
+             double format */
+          long double div10, div11, div12, div13;
+          div10 = (long double) (double) 1.797693134862315907729e308; /* 2^(2^10) */
+          div11 = div10 * div10; /* 2^(2^11) */
+          div12 = div11 * div11; /* 2^(2^12) */
+          div13 = div12 * div12; /* 2^(2^13) */
+          if (ABS(d) >= div13)
+            {
+              d = d / div13; /* exact */
+              shift_exp += 8192;
+            }
+          if (ABS(d) >= div12)
+            {
+              d = d / div12; /* exact */
+              shift_exp += 4096;
+            }
+          if (ABS(d) >= div11)
+            {
+              d = d / div11; /* exact */
+              shift_exp += 2048;
+            }
+          if (ABS(d) >= div10)
+            {
+              d = d / div10; /* exact */
+              shift_exp += 1024;
+            }
+        }
+      else if (MPFR_IS_ZERO(u) == 0 && (d != 0.0)) /* underflow */
+        { 
+          long double div10, div11, div12, div13;
+          div10 = (long double) (double) 5.5626846462680034577255e-309; /* 2^(-2^10) */
+          div11 = div10 * div10; /* 2^(-2^11) */
+          div12 = div11 * div11; /* 2^(-2^12) */
+          div13 = div12 * div12; /* 2^(-2^13) */
+          if (ABS(d) <= div13)
+            {
+              d = d / div13; /* exact */
+              shift_exp -= 8192;
+            }
+          if (ABS(d) <= div12)
+            {
+              d = d / div12; /* exact */
+              shift_exp -= 4096;
+            }
+          if (ABS(d) <= div11)
+            {
+              d = d / div11; /* exact */
+              shift_exp -= 2048;
+            }
+          if (ABS(d) <= div10)
+            {
+              d = d / div10; /* exact */
+              shift_exp -= 1024;
+            }
+        }
+      mpfr_add (t, t, u, GMP_RNDN); /* exact */
+      if (!mpfr_number_p (t))
+        break;
+      d = d - (long double) mpfr_get_d1 (u); /* exact */
+    }
+  /* now t is exactly the input value d */
+  inexact = mpfr_set (r, t, rnd_mode);
+  if (shift_exp > 0)
+    inexact2 = mpfr_mul_2exp (r, r, shift_exp, rnd_mode);
+  else if (shift_exp < 0)
+    inexact2 = mpfr_div_2exp (r, r, -shift_exp, rnd_mode);
+  if (inexact2) /* overflow */
+    inexact = inexact2;
+  mpfr_clear (t);
+  mpfr_clear (u);
+
+  return inexact;
+}