1 files changed, 99 insertions, 0 deletions
diff --git a/src/set_f.c b/src/set_f.c
new file mode 100644
index 000000000..bbd6e5efd
--- /dev/null
+++ b/src/set_f.c
@@ -0,0 +1,99 @@
+/* mpfr_set_f -- set a MPFR number from a GNU MPF number
+
+Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
+Contributed by the Arenaire and Caramel projects, INRIA.
+
+This file is part of the GNU MPFR Library.
+
+The GNU 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 3 of the License, or (at your
+option) any later version.
+
+The GNU 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 GNU MPFR Library; see the file COPYING.LESSER.  If not, see
+http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
+51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
+
+#define MPFR_NEED_LONGLONG_H
+#include "mpfr-impl.h"
+
+int
+mpfr_set_f (mpfr_ptr y, mpf_srcptr x, mpfr_rnd_t rnd_mode)
+{
+  mp_limb_t *my, *mx, *tmp;
+  unsigned long cnt, sx, sy;
+  int inexact, carry = 0;
+  MPFR_TMP_DECL(marker);
+
+  sx = ABS(SIZ(x)); /* number of limbs of the mantissa of x */
+
+  if (sx == 0) /* x is zero */
+    {
+      MPFR_SET_ZERO(y);
+      MPFR_SET_POS(y);
+      return 0; /* 0 is exact */
+    }
+
+  if (SIZ(x) * MPFR_FROM_SIGN_TO_INT(MPFR_SIGN(y)) < 0)
+    MPFR_CHANGE_SIGN (y);
+
+  sy = 1 + (MPFR_PREC(y) - 1) / GMP_NUMB_BITS;
+  my = MPFR_MANT(y);
+  mx = PTR(x);
+
+  count_leading_zeros(cnt, mx[sx - 1]);
+
+  if (sy <= sx) /* we may have to round even when sy = sx */
+    {
+      unsigned long xprec = sx * GMP_NUMB_BITS;
+
+      MPFR_TMP_MARK(marker);
+      tmp = (mp_limb_t*) MPFR_TMP_ALLOC(sx * BYTES_PER_MP_LIMB);
+      if (cnt)
+        mpn_lshift (tmp, mx, sx, cnt);
+      else
+        /* FIXME: we may avoid the copy here, and directly call mpfr_round_raw
+           on mx instead of tmp */
+        MPN_COPY (tmp, mx, sx);
+      carry = mpfr_round_raw (my, tmp, xprec, (SIZ(x) < 0), MPFR_PREC(y),
+                              rnd_mode, &inexact);
+      if (MPFR_UNLIKELY(carry)) /* result is a power of two */
+        my[sy - 1] = MPFR_LIMB_HIGHBIT;
+      MPFR_TMP_FREE(marker);
+    }
+  else
+    {
+      if (cnt)
+        mpn_lshift (my + sy - sx, mx, sx, cnt);
+      else
+        MPN_COPY (my + sy - sx, mx, sx);
+      MPN_ZERO(my, sy - sx);
+      /* no rounding necessary, since y has a larger mantissa */
+      inexact = 0;
+    }
+
+  /* warning: EXP(x) * GMP_NUMB_BITS may exceed the maximal exponent */
+  if (EXP(x) > 1 + (__gmpfr_emax - 1) / GMP_NUMB_BITS)
+    {
+      /* EXP(x) >= 2 + floor((__gmpfr_emax-1)/GMP_NUMB_BITS)
+         EXP(x) >= 2 + (__gmpfr_emax - GMP_NUMB_BITS) / GMP_NUMB_BITS
+                >= 1 + __gmpfr_emax / GMP_NUMB_BITS
+         EXP(x) * GMP_NUMB_BITS >= __gmpfr_emax + GMP_NUMB_BITS
+         Since 0 <= cnt <= GMP_NUMB_BITS-1, and 0 <= carry <= 1,
+         we have then EXP(x) * GMP_NUMB_BITS - cnt + carry > __gmpfr_emax */
+      return mpfr_overflow (y, rnd_mode, MPFR_SIGN (y));
+    }
+  else
+    {
+      /* Do not use MPFR_SET_EXP as the exponent may be out of range. */
+      MPFR_EXP (y) = EXP (x) * GMP_NUMB_BITS - (mpfr_exp_t) cnt + carry;
+    }
+
+  return mpfr_check_range (y, inexact, rnd_mode);
+}