Reorganisation of the source tree

[ghc-hetmet.git] / rts / gmp / mpz / fdiv_q_2exp.c

diff --git a/rts/gmp/mpz/fdiv_q_2exp.c b/rts/gmp/mpz/fdiv_q_2exp.c
new file mode 100644 (file)
index 0000000..8e02180
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+++ b/rts/gmp/mpz/fdiv_q_2exp.c
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+/* mpz_fdiv_q_2exp -- Divide an integer by 2**CNT.  Round the quotient
+   towards -infinity.
+
+Copyright (C) 1991, 1993, 1994, 1996, 1998, 1999 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"
+
+void
+#if __STDC__
+mpz_fdiv_q_2exp (mpz_ptr w, mpz_srcptr u, unsigned long int cnt)
+#else
+mpz_fdiv_q_2exp (w, u, cnt)
+     mpz_ptr w;
+     mpz_srcptr u;
+     unsigned long int cnt;
+#endif
+{
+  mp_size_t usize = u->_mp_size;
+  mp_size_t wsize;
+  mp_size_t abs_usize = ABS (usize);
+  mp_size_t limb_cnt;
+  mp_ptr wp;
+  mp_limb_t round = 0;
+
+  limb_cnt = cnt / BITS_PER_MP_LIMB;
+  wsize = abs_usize - limb_cnt;
+  if (wsize <= 0)
+    {
+      wp = w->_mp_d;
+      wsize = 0;
+      /* Set ROUND since we know we skip some non-zero words in this case.
+        Well, if U is zero, we don't, but then this will be taken care of
+        below, since rounding only really takes place for negative U.  */
+      round = 1;
+      wp[0] = 1;
+      w->_mp_size = -(usize < 0);
+      return;
+    }
+  else
+    {
+      mp_size_t i;
+      mp_ptr up;
+
+      /* Make sure there is enough space.  We make an extra limb
+        here to account for possible rounding at the end.  */
+      if (w->_mp_alloc < wsize + 1)
+       _mpz_realloc (w, wsize + 1);
+
+      wp = w->_mp_d;
+      up = u->_mp_d;
+
+      /* Set ROUND if we are about skip some non-zero limbs.  */
+      for (i = 0; i < limb_cnt && round == 0; i++)
+       round = up[i];
+
+      cnt %= BITS_PER_MP_LIMB;
+      if (cnt != 0)
+       {
+         round |= mpn_rshift (wp, up + limb_cnt, wsize, cnt);
+         wsize -= wp[wsize - 1] == 0;
+       }
+      else
+       {
+         MPN_COPY_INCR (wp, up + limb_cnt, wsize);
+       }
+    }
+
+  if (usize < 0 && round != 0)
+    {
+      mp_limb_t cy;
+      if (wsize != 0)
+       {
+         cy = mpn_add_1 (wp, wp, wsize, (mp_limb_t) 1);
+         wp[wsize] = cy;
+         wsize += cy;
+       }
+      else
+       {
+         /* We shifted something negative to zero.  The result is -1.  */
+         wp[0] = 1;
+         wsize = 1;
+       }
+    }
+  w->_mp_size = usize >= 0 ? wsize : -wsize;
+}