Reorganisation of the source tree

[ghc-hetmet.git] / rts / gmp / mpz / get_d.c

diff --git a/rts/gmp/mpz/get_d.c b/rts/gmp/mpz/get_d.c
new file mode 100644 (file)
index 0000000..6a7c585
--- /dev/null
+++ b/rts/gmp/mpz/get_d.c
@@ -0,0 +1,128 @@
+/* double mpz_get_d (mpz_t src) -- Return the double approximation to SRC.
+
+Copyright (C) 1996, 1997, 2000 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP 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 MP 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 MP 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 "longlong.h"
+
+
+static int
+#if __STDC__
+mpn_zero_p (mp_ptr p, mp_size_t n)
+#else
+mpn_zero_p (p, n)
+     mp_ptr p;
+     mp_size_t n;
+#endif
+{
+  mp_size_t i;
+
+  for (i = 0; i < n; i++)
+    {
+      if (p[i] != 0)
+       return 0;
+    }
+
+  return 1;
+}
+
+
+double
+#if __STDC__
+mpz_get_d (mpz_srcptr src)
+#else
+mpz_get_d (src)
+     mpz_srcptr src;
+#endif
+{
+  double res;
+  mp_size_t size;
+  int negative;
+  mp_ptr qp;
+  mp_limb_t hz, lz;
+  int cnt;
+
+  size = SIZ(src);
+  if (size == 0)
+    return 0.0;
+
+  negative = size < 0;
+  size = ABS (size);
+  qp = PTR(src);
+
+  if (size == 1)
+    {
+      res = qp[size - 1];
+    }
+  else if (size == 2)
+    {
+      res = MP_BASE_AS_DOUBLE * qp[size - 1] + qp[size - 2];
+    }
+  else
+    {
+      count_leading_zeros (cnt, qp[size - 1]);
+
+#if BITS_PER_MP_LIMB == 32
+      if (cnt == 0)
+       {
+         hz = qp[size - 1];
+         lz = qp[size - 2];
+       }
+      else
+       {
+         hz = (qp[size - 1] << cnt) | (qp[size - 2] >> BITS_PER_MP_LIMB - cnt);
+         lz = (qp[size - 2] << cnt) | (qp[size - 3] >> BITS_PER_MP_LIMB - cnt);
+       }
+#if _GMP_IEEE_FLOATS
+      /* Take bits from less significant limbs, but only if they may affect
+        the result.  */
+      if ((lz & 0x7ff) == 0x400)
+       {
+         if (cnt != 0)
+           lz += ((qp[size - 3] << cnt) != 0 || ! mpn_zero_p (qp, size - 3));
+         else
+           lz += (! mpn_zero_p (qp, size - 2));
+       }
+#endif
+      res = MP_BASE_AS_DOUBLE * hz + lz;
+      res = __gmp_scale2 (res, (size - 2) * BITS_PER_MP_LIMB - cnt);
+#endif
+#if BITS_PER_MP_LIMB == 64
+      if (cnt == 0)
+       hz = qp[size - 1];
+      else
+       hz = (qp[size - 1] << cnt) | (qp[size - 2] >> BITS_PER_MP_LIMB - cnt);
+#if _GMP_IEEE_FLOATS
+      if ((hz & 0x7ff) == 0x400)
+       {
+         if (cnt != 0)
+           hz += ((qp[size - 2] << cnt) != 0 || ! mpn_zero_p (qp, size - 2));
+         else
+           hz += (! mpn_zero_p (qp, size - 1));
+       }
+#endif
+      res = hz;
+      res = __gmp_scale2 (res, (size - 1) * BITS_PER_MP_LIMB - cnt);
+#endif
+    }
+
+  return negative ? -res : res;
+}