Rewrite.

1 files changed, 29 insertions, 34 deletions

diff --git a/mpz/mul_2exp.c b/mpz/mul_2exp.c
index a1521816e..4e1f4e6bd 100644
--- a/mpz/mul_2exp.c
+++ b/mpz/mul_2exp.c
@@ -1,6 +1,7 @@
 /* mpz_mul_2exp -- Multiply a bignum by 2**CNT
 
-Copyright 1991, 1993, 1994, 1996, 2001, 2002 Free Software Foundation, Inc.
+Copyright 1991, 1993, 1994, 1996, 2001, 2002, 2012 Free Software Foundation,
+Inc.
 
 This file is part of the GNU MP Library.
 
@@ -21,47 +22,41 @@ along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
 #include "gmp-impl.h"
 
 void
-mpz_mul_2exp (mpz_ptr w, mpz_srcptr u, mp_bitcnt_t cnt)
+mpz_mul_2exp (mpz_ptr r, mpz_srcptr u, mp_bitcnt_t cnt)
 {
-  mp_size_t usize = u->_mp_size;
-  mp_size_t abs_usize = ABS (usize);
-  mp_size_t wsize;
+  mp_size_t un, rn;
   mp_size_t limb_cnt;
-  mp_ptr wp;
-  mp_limb_t wlimb;
-
-  if (usize == 0)
-    {
-      w->_mp_size = 0;
-      return;
-    }
+  mp_ptr rp;
+  mp_srcptr up;
+  mp_limb_t rlimb;
 
+  un = ABSIZ (u);
   limb_cnt = cnt / GMP_NUMB_BITS;
-  wsize = abs_usize + limb_cnt + 1;
-  if (w->_mp_alloc < wsize)
-    _mpz_realloc (w, wsize);
-
-  wp = w->_mp_d;
-  wsize = abs_usize + limb_cnt;
+  rn = un + limb_cnt;
 
-  cnt %= GMP_NUMB_BITS;
-  if (cnt != 0)
+  if (un == 0)
+    rn = 0;
+  else
     {
-      wlimb = mpn_lshift (wp + limb_cnt, u->_mp_d, abs_usize, cnt);
-      if (wlimb != 0)
+      rp = MPZ_REALLOC (r, rn + 1);
+      up = PTR(u);
+
+      cnt %= GMP_NUMB_BITS;
+      if (cnt != 0)
 	{
-	  wp[wsize] = wlimb;
-	  wsize++;
+	  rlimb = mpn_lshift (rp + limb_cnt, up, un, cnt);
+	  rp[rn] = rlimb;
+	  rn += (rlimb != 0);
+	}
+      else
+	{
+	  MPN_COPY_DECR (rp + limb_cnt, up, un);
 	}
-    }
-  else
-    {
-      MPN_COPY_DECR (wp + limb_cnt, u->_mp_d, abs_usize);
-    }
 
-  /* Zero all whole limbs at low end.  Do it here and not before calling
-     mpn_lshift, not to lose for U == W.  */
-  MPN_ZERO (wp, limb_cnt);
+      /* Zero all whole limbs at low end.  Do it here and not before calling
+	 mpn_lshift, not to lose for U == R.  */
+      MPN_ZERO (rp, limb_cnt);
+    }
 
-  w->_mp_size = usize >= 0 ? wsize : -wsize;
+  SIZ(r) = SIZ(u) >= 0 ? rn : -rn;
 }