Imported gcc-4.4.3

[msp430-gcc.git] / gmp / mpf / div.c

diff --git a/gmp/mpf/div.c b/gmp/mpf/div.c
new file mode 100644 (file)
index 0000000..ef3675e
--- /dev/null
+++ b/gmp/mpf/div.c
@@ -0,0 +1,146 @@
+/* mpf_div -- Divide two floats.
+
+Copyright 1993, 1994, 1996, 2000, 2001, 2002, 2004, 2005 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 3 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.  If not, see http://www.gnu.org/licenses/.  */
+
+#include <stdio.h>  /* for NULL */
+#include "gmp.h"
+#include "gmp-impl.h"
+#include "longlong.h"
+
+
+/* Not done:
+
+   No attempt is made to identify an overlap u==v.  The result will be
+   correct (1.0), but a full actual division is done whereas of course
+   x/x==1 needs no work.  Such a call is not a sensible thing to make, and
+   it's left to an application to notice and optimize if it might arise
+   somehow through pointer aliasing or whatever.
+
+   Enhancements:
+
+   The high quotient limb is non-zero when high{up,vsize} >= {vp,vsize}.  We
+   could make that comparison and use qsize==prec instead of qsize==prec+1,
+   to save one limb in the division.
+
+   If r==u but the size is enough bigger than prec that there won't be an
+   overlap between quotient and dividend in mpn_tdiv_qr, then we can avoid
+   copying up,usize.  This would only arise from a prec reduced with
+   mpf_set_prec_raw and will be pretty unusual, but might be worthwhile if
+   it could be worked into the copy_u decision cleanly.
+
+   Future:
+
+   If/when mpn_tdiv_qr supports its qxn parameter we can use that instead of
+   padding u with zeros in temporary space.
+
+   If/when a quotient-only division exists it can be used here immediately.
+   remp is only to satisfy mpn_tdiv_qr, the remainder is not used.  */
+
+void
+mpf_div (mpf_ptr r, mpf_srcptr u, mpf_srcptr v)
+{
+  mp_srcptr up, vp;
+  mp_ptr rp, remp, tp, new_vp;
+  mp_size_t usize, vsize, rsize, prospective_rsize, tsize, zeros, copy_v_size;
+  mp_size_t sign_quotient, prec, high_zero, chop;
+  mp_exp_t rexp;
+  int copy_u;
+  TMP_DECL;
+
+  usize = u->_mp_size;
+  vsize = v->_mp_size;
+  sign_quotient = usize ^ vsize;
+  usize = ABS (usize);
+  vsize = ABS (vsize);
+  prec = r->_mp_prec;
+
+  if (vsize == 0)
+    DIVIDE_BY_ZERO;
+
+  if (usize == 0)
+    {
+      r->_mp_size = 0;
+      r->_mp_exp = 0;
+      return;
+    }
+
+  TMP_MARK;
+  rexp = u->_mp_exp - v->_mp_exp + 1;
+
+  rp = r->_mp_d;
+  up = u->_mp_d;
+  vp = v->_mp_d;
+
+  prospective_rsize = usize - vsize + 1; /* quot from using given u,v sizes */
+  rsize = prec + 1;                      /* desired quot */
+
+  zeros = rsize - prospective_rsize;     /* padding u to give rsize */
+  copy_u = (zeros > 0 || rp == up);      /* copy u if overlap or padding */
+
+  chop = MAX (-zeros, 0);                /* negative zeros means shorten u */
+  up += chop;
+  usize -= chop;
+  zeros += chop;                         /* now zeros >= 0 */
+
+  tsize = usize + zeros;                 /* size for possible copy of u */
+
+  if (WANT_TMP_DEBUG)
+    {
+      /* separate blocks, for malloc debugging */
+      remp = TMP_ALLOC_LIMBS (vsize);
+      tp = (copy_u ? TMP_ALLOC_LIMBS (tsize) : NULL);
+      new_vp = (rp == vp ? TMP_ALLOC_LIMBS (vsize) : NULL);
+    }
+  else
+    {
+      /* one block with conditionalized size, for efficiency */
+      copy_v_size = (rp == vp ? vsize : 0);
+      remp = TMP_ALLOC_LIMBS (vsize + copy_v_size + (copy_u ? tsize : 0));
+      new_vp = remp + vsize;
+      tp = new_vp + copy_v_size;
+    }
+
+  /* copy and possibly extend u if necessary */
+  if (copy_u)
+    {
+      MPN_ZERO (tp, zeros);
+      MPN_COPY (tp+zeros, up, usize);
+      up = tp;
+      usize = tsize;
+    }
+
+  /* ensure divisor doesn't overlap quotient */
+  if (rp == vp)
+    {
+      MPN_COPY (new_vp, vp, vsize);
+      vp = new_vp;
+    }
+
+  ASSERT (usize-vsize+1 == rsize);
+  mpn_tdiv_qr (rp, remp, (mp_size_t) 0, up, usize, vp, vsize);
+
+  /* strip possible zero high limb */
+  high_zero = (rp[rsize-1] == 0);
+  rsize -= high_zero;
+  rexp -= high_zero;
+
+  r->_mp_size = sign_quotient >= 0 ? rsize : -rsize;
+  r->_mp_exp = rexp;
+  TMP_FREE;
+}