Initial revision

1 files changed, 133 insertions, 0 deletions

diff --git a/mpz/set_d.c b/mpz/set_d.c
new file mode 100644
index 000000000..c31beadc4
--- /dev/null
+++ b/mpz/set_d.c
@@ -0,0 +1,133 @@
+/* mpz_set_d(integer, val) -- Assign INTEGER with a double value VAL.
+
+Copyright (C) 1995 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 Library General Public License as published by
+the Free Software Foundation; either version 2 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 Library General Public
+License for more details.
+
+You should have received a copy of the GNU Library 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 <math.h>
+
+#define MP_BASE_AS_DOUBLE (2.0 * ((mp_limb_t) 1 << (BITS_PER_MP_LIMB - 1)))
+
+void
+#if __STDC__
+mpz_set_d (mpz_ptr dest, double val)
+#else
+mpz_set_d (dest, val)
+     mpz_ptr dest;
+     double val;
+#endif
+{
+  int negative;
+  double base;
+  int mexp;
+  unsigned exp;
+  mp_size_t size;
+
+  negative = val < 0;
+  val = fabs (val);
+
+  /* Zero is not handled correctly by the code below.  */
+  if (val < 1)
+    {
+      dest->_mp_size = 0;
+      return;
+    }
+  /* Handle small arguments quickly.  */
+  if (val < MP_BASE_AS_DOUBLE)
+    {
+      dest->_mp_d[0] = val;
+      dest->_mp_size = negative ? -1 : 1;
+      return;
+    }
+
+  base = frexp (val, &mexp);
+  exp = mexp;
+
+#if BITS_PER_MP_LIMB >= 64
+  {
+    double dlo, dhi;
+    mp_size_t lexp, bexp;
+    mp_limb_t l0, l1, l2;
+    mp_ptr rp = dest->_mp_d;
+
+    l0 = base * MP_BASE_AS_DOUBLE;
+    lexp = exp / BITS_PER_MP_LIMB;
+    bexp = exp % BITS_PER_MP_LIMB;
+    if (bexp != 0)
+      {
+	l1 = l0 >> (BITS_PER_MP_LIMB - bexp);
+	l0 = l0 << bexp;
+      }
+    else
+      {
+	l1 = l0;
+	l0 = 0;
+	lexp--;
+      }
+    MPN_ZERO (rp, lexp - 1);
+    rp[lexp - 1] = l0;
+    rp[lexp] = l1;
+    size = lexp + 1;
+  }
+#endif
+#if BITS_PER_MP_LIMB < 64
+  {
+    double dlo, dhi;
+    mp_size_t lexp, bexp;
+    mp_limb_t l0, l1, l2;
+    mp_ptr rp = dest->_mp_d;
+
+    dlo = modf (base * MP_BASE_AS_DOUBLE, &dhi);
+    l0 = dlo * MP_BASE_AS_DOUBLE;
+    l1 = dhi;
+    lexp = exp / BITS_PER_MP_LIMB;
+    bexp = exp % BITS_PER_MP_LIMB;
+    if (bexp != 0)
+      {
+	l2 = l1 >> (BITS_PER_MP_LIMB - bexp);
+	l1 = (l1 << bexp) | (l0 >> (BITS_PER_MP_LIMB - bexp));
+	l0 = l0 << bexp;
+      }
+    else
+      {
+	l2 = l1;
+	l1 = l0;
+	l0 = 0;
+	lexp--;
+      }
+    if (exp <= 2 * BITS_PER_MP_LIMB)
+      {
+	rp[0] = l1;
+	rp[1] = l2;
+	size = 2;
+      }
+    else
+      {
+	MPN_ZERO (rp, lexp - 2);
+	rp[lexp - 2] = l0;
+	rp[lexp - 1] = l1;
+	rp[lexp] = l2;
+	size = lexp + 1;
+      }
+  }
+#endif
+
+  dest->_mp_size = negative ? -size : size;
+}